bidding document

bidding document
POWER GRID COMPANY OF BANGLADESH LIMITED
ISO 9001:2008 Certified
BIDDING DOCUMENT
for
Design, supply, installation, testing and commissioning of 132/33kV
Substations at Nawabganj, Srinagar, Narail, Jhenaidaha and Magura
Under
Enhancement of Capacity of Grid Substations and Transmission Lines for
Rural Electrification under Rural Electricity Transmission and Distribution
(T&D) Project of the World Bank.
IDA Credit: 5381-BD
ICB No.: PGCB/W-04
(Bid Identification No.: PGCB/WB/ ECGSTL/SS/W04)
Issued on:
Employer: Power Grid Company of Bangladesh Limited
Country: The People’s Republic of Bangladesh
Volume 2 of 2
EMPLOYER’S REQUIREMENT
NOVEMBER 2015
POWER GRID COMPANY OF BANGLADESH LIMITED
ISO 9001:2008 Certified
BIDDING DOCUMENT
for
Design, supply, installation, testing and commissioning of 132/33kV
Substations at Nawabganj, Srinagar, Narail, Jhenaidaha and
Magura.
INDEX TO VOLUMES
Volume 2 of 2 [Employer’s Requirement]
Scope of Work and Schedule of Requirement
Section 1 - Scope of Work and Schedule of Requirement
Technical Specification
Section 2 - Ancillary Mechanical and Electrical Apparatus.
Section 3 - HV AIR INSULATED SWITCHGEAR EQUIPMENT
Section 4 - Transformer
Section 5 - Protection, Control, Metering and Substation Automation
Section 6 - Auxiliary Power and Control Cables
Section 7 - Earthing Systems, Electrodes Connections
Section 8 - Batteries, Chargers and DC Distribution Switchgear
Section 9 - LV AC Distribution Switchgear
Section 10 – Building and Civil Engineering Works
Section 11 – Supporting Structures for Outdoor Equipment
Section 12 – Lighting, Small Power, Heating and Ventilation
Section 13 – Fibre Optic Multiplexer Equipment for Communication and Protection
Section 14 – Power Cables and Cable Terminating Accessories
Section 15 – Quality Assurance, Inspection, Testing, Commissioning and Warranty
Section 16 – National Load Despatch Centre (NLDC) Control Facilities
Section 17 – Environment Management
Bid Drawings
Section 18 – Drawings
Scope of Work and Schedule of Requirement
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION I
SCOPE OF WORK AND SCHEDULE OF REQUIREMENT
Section 1
Scope of Work
SECTION 1(PART-A)
SCOPE OF WORK
CONTENTS
CLAUSE NO.
TITLE
PAGE NO.
1.1
DESCRIPTION OF OVERALL PROJECT............................................... 1
1.2
DESCRIPTION OF THIS BID ................................................................. 1
1.3
TERMINAL POINTS ................................................................................ 3
1.3.1
230 KV AND 132 KV OVERHEAD LINE CIRCUIT CONNECTIONS ................................ 4
1.3.2
COMMUNICATIONS AND SCADA EQUIPMENT .......................................................... 5
1.4
SYSTEM ELECTRICAL PARAMETERS................................................. 5
1.4.1
SYSTEM CONDITIONS ............................................................................................... 5
1.4.2
SYSTEM EARTHING................................................................................................... 6
1.4.3
MINIMUM SUBSTATION CLEARANCES ...................................................................... 6
1.4.4
LOW VOLTAGE AC SYSTEM ...................................................................................... 6
1.4.5
D.C. SYSTEM ............................................................................................................ 6
1.5
CLIMATIC CONDITIONS ........................................................................ 7
i
Section 1
Scope of Work
SECTION 1SCOPE OF WORK
1.1
DESCRIPTION OF OVERALL PROJECT
The Government of Bangladesh has received a loan from the International Development
Association (IDA) for Enhancement of Capacity of Grid Substations and Transmission Lines for
Rural Electrification, which will be implemented by the Power Grid Company of Bangladesh
Limited(PGCB).
1.2
DESCRIPTION OF THIS BID
The salient features of the work covered by this Bid and Specification is outlined below,
for132kV &33 kV rated voltage Air Insulated Switchgear (AIS) substation plant and civil works.
This Bidding Document is for the design, manufacture, quality assurance, new packing for
export, insurance and shipment to site, complete construction and installation, jointing,
terminating, bonding, earthing, painting, setting to work, site testing and commissioning,
warranty for a period of 365 days for all equipment, including all civil works.
The detailed requirements are listed inschedule Aand price schedule of volume 1 of 2 of the
bidding document. The brief description of works under this contract is as follows:
Scope 1
NEW 132/33KV AIS SUBSTATION AT NAWABGANJ:
(i) Design, supply, delivery, installation, testing & commissioning of a
complete new 132/33kV AIS substation at Nawabganj (which is
situated at the south side and about 50km away from the center
of capital Dhaka);
Complete 132kV AIS Subsation consisting of Two line bays, Two
transformer bays & one bus coupler bay to connect two new 132 kV
overhead lines (Keraniganj-1& 2) and two new 132/33kV, 50/75MVA
transformer including 33kV switching Station consisting ten(10) 33kV
outgoing feeder. The configuration of the 132kV busbar shall be
double busbar scheme& 33kV shall be single busbar scheme.
Scope 2
NEW 132/33KV AIS SUBSTATION AT SRINAGAR:
(i) Design, supply, delivery, installation, testing & commissioning of a
complete new 132/33kV AIS substation at Srinagar (which is
situated at the south side and about 50km away from the center
of capital Dhaka);
1
Section 1
Scope of Work
Complete 132kV AIS Subsation consisting of Two line bays, Two
transformer bays & one bus coupler bay to connect two new 132 kV
overhead lines (Keraniganj PP -1& 2) and two new 132/33kV,
50/75MVA transformer including 33kV switching Station consisting
ten(10) 33kV outgoing feeder. The configuration of the 132kV busbar
shall be double busbar scheme& 33kV shall be single busbar
scheme.
Scope 3
NEW 132/33KV AIS SUBSTATION AT NARAIL:
(i) Design, supply, delivery, installation, testing & commissioning of a
complete new 132/33kV AIS substation at Narail (which is
situated at the west side and about 250km away from the center
of capital Dhaka);
Complete 132kV AIS Low cost Subsation consisting of Two line bays
andTwo transformer bays to connect two new 132 kV overhead lines
(Magura-1& 2) and two new 132/33kV, 50/75MVA transformer
including 33kV switching Station consisting six(6) 33kv outgoing
feeder. The configuration of the 132kV & 33kV busbar shall be single
busbar scheme.
Scope 4
Extension of existing 132/33kV AIS Substation at Jhenaidaha:
(i) Jhenaidaha Substation is situated at the west side, about 200km
away from the capital city Dhaka.
The configuration of the existing 132kV busbar is double bus
arrangement and consists of six(6) line bays, two(2) transformer
bays and one(1) bus tie bay including future space for two bays. The
complete new 132kV bay equipment shall be installed for one bay
extension to connect Magura-2nd 132kV circuit.
Scope 5
Extension of existing 132/33kV AIS Substation at Magura:
(i) Magura Substation is situated at the west side, about 170km
away from the capital city Dhaka.
The configuration of the existing 132kV busbar is main and transfer
bus arrangement and consists of one(1) line bays, two(2)
transformer bays and one(1) bus tie bay including future space for
three bays. Three(3)complete new 132kV bay equipment shall be
installed for three(3) bay extension to connect jhenaidaha-2nd 132kV
circuit and Narail –(1 & 2) 132kV circuit.
The “Schedule of Requirements” for equipment, materials and services and the Detailed
Technical Specifications of equipment and materials as included in Volume 2 of 2 of the
2
Section 1
Scope of Work
BiddingDocument shall be read in conjunction with the scope of work described herein. The
drawings provided in the Bidding Document are indicative only and hence the entire scope of
work is not fully reflected in those drawings.The Contractor shall develop the full set of
drawings to reflect the requirements in the scope of works.
Within one month of the signing of the Contract, the Contractor shall submit a program chart
detailing times required for the design, manufacture, testing, delivery and erection for the
complete contract.
The Contractor is responsible for ensuring that all and any items of work required for the safe,
efficient and satisfactory completion and functioning of the works, are included in the Bid price
whether they be described in the specification or not.
This Bid provides for all parts of the works to be completed in every respect for commercial
operation to the requirements of the Engineer. All details, accessories etc. required for the
complete installation and satisfactory operation of the works not specifically mentioned in this
Specification are deemed to be included in the contract price.
Training and Witness:
(1) Factory Acceptance Test (FAT) Witness:
The contract price shall include all costs of witnessing of factory acceptance tests by
Employer's engineer. Total six(6) nos. of visit for witnessing of factory acceptance tests
by Employer's engineer (two engineers in each visit, and seven days for each visit) is
required for the following equipment’s:
(i)132/33kV power transformers
(ii) 132kV & 33kV Circuit Breaker
(iii) 132kV & 33kV Disconnector Switches
(iv) 132kV & 33kV Current Transformer & Voltage Transformer.
(v) 132kV & 33kV Surge Arrester
(vi) SAS,Control & protection equipment
The Contractor shall be responsible for bearing all costs for the Employer’s engineers,
including air fares, accommodation, meal, healthcare, laundry, transportation, visa fees
etc. together with payment of a daily allowance of US$ 100 for each of the Employer's
engineer.
(2) Training:
The contract price shall include all costs of foreign and local training for Employer's
engineer.
Foreign Training:
3
Section 1
Scope of Work
- Overseas training of Employer's engineer (two engineers in each visit and three weeks
for each visit) for each of the following subject at manufacturer’s Training institute is
required.
(i) Substation automation, control & protection systems
(ii) Telecommunication &Teleportation(including SCADA) system for HV substation.
- Overseas training on Substation design for Employer's engineer(two engineers in one
visit) at an internationally specialized training institute is also required and the duration
of training shall be three weeks.
The Contractor shall be responsible for bearing all costs for the trainees, including air
fares, accommodation, meal, healthcare, laundry, transportation, visa fees etc. together
with payment of a daily allowance of US$ 70 for each of the Employer's trainee.
Local Training:
The Contractor shall be responsible for providing instruction and guidance to PGCB
personnel in the operation and maintenance of the substation equipment. During the
installation the Contractor should provide minimum one trainer (authorised by the
manufacturer) for training of Employer's personnel on site for minimum one week for
training of Substation operation & maintenance and for one week for training of
substation automation, control & protection system so that they could get a clear idea
about operation, inspection/maintenance of the equipment. The number of trainee for
each Training shall be 15(fifteen) in each Training program. The contractor shall be
responsible for providing lunch and training material to the trainee.
1.3
TERMINAL POINTS
1.3.1
230 kV and 132 kV Overhead Line Circuit Connections
The slack spans including overhead earth wires between the 230 kV terminal tower and the
substation gantry structures shall be supplied and terminated by the overhead line contractors.
All required insulators and hardware’s shall also be supplied by the overhead line contractor.
Eyebolts/U-bolts or other suitable fixtures for terminating the slack spans on the switchyard
gantry shall be provided under the substation Contract (Contractor under this Contract).
The substation Contractor (Contractor under this Contract) shall provide all the jumpers from
the slack span to the substation equipment on the substation entry equipment by fixing
appropriate T-terminals on the slack span conductor or other approved means. The supply of
appropriate clamps and the actual termination of the jumper to the substation equipment shall
be carried out under this Contract.
Bonding of the incoming earth wire to the station earthing screen and supply of earthing
conductor and connection of the terminal tower earth electrode into the substation earth grid
shall be carried out under this Contract.
4
Section 1
Scope of Work
The overhead line Contractor shall terminate the OPGW at the substation gantry in the
terminal joint boxes provided by the overhead line Contractor.
The connection between OPGW joint boxes at Substation gantry and control room building via
underground optical fibre cables shall be carried out under this Contract which includes supply
& installation of fibre optic cable of size similar to OPGW.
1.3.2
Communications and SCADA Equipment
The voice communication, teleprotection signalling and main distribution frame (MDF) for
optical fibre cable will be supplied and installed under this Contract. Necessary equipment for
incorporating new 230kV & 132kV system into the existing SCADA system shall also be
supplied and installed under this Contract
In order to provide the telecontrol & telemetering (SCADA) facilities required at the existing
National Load Despatch Center(NLDC) at Aftabnagar, and also back up NLDC at Biddut
Bhaban,Dhaka; all plant supplied under this Contract shall be equipped with potential free
auxiliary contacts for indications and alarms. CT and VT circuits shall be fitted, where required,
with the appropriate shorting and fused terminals. All required electrical signals shall be
transmitted to the NLDC through the Industrial Gateway of the substation automation system.
All HV breakers, motorized disconnectors, tap changer, etc. shall be controlled form NLDC
through the Gateway of the substation automation system using IEC 60870-5- 104 protocol.
Necessary transducer, control & interposing relays, RTU’s, etc. shall be used. Necessary
interfacing between the Substation Automation gateway and the communication equipment is
to be carried out.
In addition, to realize the complete SCADA system after completion of the Project, modification
of the existing software in the master computer of the national load despatch centre, and
modification of hardware (installing additional printed circuit cards etc. if required) shall be
made under this Contract.
1.4
SYSTEM ELECTRICAL PARAMETERS
1.4.1
System Conditions
Equipment supplied under this Contract shall be suitable for the following system conditions.
Nominal system voltage between phases
kV
230
132
33
System frequency
Hz
Rated voltage between phases
kV
245
145
36
Lightning impulse withstand
kV
1050
650
170
50 Hz withstand 1 minute
kV
460
275
70
Symmetrical short-circuit current (3 sec)
kA
50
40
31.5
----------50----------
5
Section 1
1.4.2
Scope of Work
System Earthing
The 230/132/33kV auto transformers and 132/33kV power transformers are solidly earthed.
The 132 kV system is solidly earthed at the power station transformer 132 kV neutrals and
230/132 kV auto-transformer neutrals but not earthed at the 132/33 kV Grid supply points.
The 33 kV system is solidly earthed at some of the 132/33 kV grid substations and resistance
earthed at some of the grid substations.
1.4.3
Minimum Substation Clearances
Air insulated busbars and connections shall have electrical clearances as listed in the following
table:Nominal system voltage
Minimum clearance between live metal
and earth
Minimum clearance between live metal
Minimum safety clearance between
ground and the nearest point not
at earth potential of an insulator
Minimum safety clearance between
ground and the nearest live unscreened
conductor (BS 7354 'Safety
Working Clearance')
Minimum insulator creepage distance
(at rated voltage between phases)
1.4.4
230
2100
132
1300
33
360
mm
2400
1500
430
mm
2500
2500
2500
mm
4270
3500
2740
25
25
25
mm/kV
Low Voltage AC System
Rated service voltage
Tolerance on rated voltage
Switchgear symmetrical breaking capacity
System earthing
1.4.5
kV
mm
415/230 volts
(3 phase, 4 wire 50 Hz)
+10%,-10%
15 kA, 3 sec
Solid
D.C. System
For D.C. motor driven auxiliaries, relays, tripping, indicating lamps and controls.
Normal battery voltage
110 V nominal
Tolerance on rated voltage
For telecommunication & future SCADA
Normal battery voltage
+10%,-10%
48 V nominal for new substation
6
Section 1
Scope of Work
Tolerance on rated voltage
1.5
+10%,-10%
CLIMATIC CONDITIONS
All plant and equipment supplied under the Contract shall be entirely suitable for the climatic
conditions mentioned below, and that will prevail over any data in the specification.
The project area and vicinity is close to sea level and is in a tropical climate. The ambient
shade temperature variation is between 4˚C and 45˚C with periods of high humidity.
Between May and November low lying areas are subject to flooding.
The flooding can be taken advantage of at certain Sites in that the heavy loads may be floated
on barges to close proximity to the Sites.
The project area is designated a zone of moderate intensity for earthquakes.
The seismic factor is 0.05 g to 0. 1 g.
Atmospheric pollution is moderate and special insulator design or washing is not required. The
area is subject to high winds of typhoon strength.
Maximum ambient shade temperature
Minimum ambient shade temperature
45˚C
4˚C
Maximum daily average temperature
Maximum annual average temperature
35˚C
25˚C
Maximum wind velocity
Minimum wind velocity for line rating purposes
Solar radiation
160 Km/h
3.2 Km/h (132/230kV)
100mW/sq.cm
Rainfall
Relative humidity, maximum
Relative humidity, average
Altitude
Atmospheric Pollution
(No ice or snow expected)
Soil type
Soil temperature (at 1.1m)
Soil thermal resistivity
Isokeraunic Level (Thunderstorm days/year)
2.5 m/annum
100%
80%
less than 150 m
light
alluvial
30˚C
1.5˚C m/W
80
7
Section 1.
Requirements
SECTION 1(PART-B)
SCHEDULE OF REQUIREMENTS
Schedule A: Requirements
Section 1
Requirements
TABLE OF CONTENT
DESCRIPTION
SCHEDULE A
INTRODUCTION & PREAMBLE TO THE PRICE &
TECHNICALSCHEDULES
A1Brief Description Of The Works
A2Description Of Works For The Price Schedule
A3 Schedule Of Technical Requirements
A4 Type Test Requirements
2
Section 1.
Requirements
SCHEDULE A
INTRODUCTION & PREAMBLE TO THE PRICE & TECHNICAL SCHEDULES
A1: BRIEF DESCRIPTION OF THE WORKS
The bidder shall be deemed to have visited site, inspected, gathered data and verified details
of the as-built system in order to design, supply and interface their new equipment. All
necessary materials, adjustments, dismantling, remedial and tiding-up work in order to
complete the work specified shall be included in the contract price. The contractor is
responsible for ensuring that all and/or and any item(s) of work required for the safe,
efficient and satisfactory completion and functioning of the works, are included in the
Bid Price whether they be described in the specification or not.
Equivalent international standard will also be accepted inplace of the standard
referenced in this document.
The scope of work comprises the following: DESCRIPTION OF WORKS
The scope of work under this bid is for design, supply, delivery, installation, testing &
commissioning of three new 132/33kV Air Insulated Switchgear (AIS) substation at Nawabganj,
Srinagar & Narailincluding 33kV AIS switching Station and extension of existing 132/33kV
substation atJhenaidaha & Magura.
The scope of work also includes design, supply, delivery, installation, testing & commissioning of
132/33kV power transformer and associated control, automation, protection, fiber optic
multiplexer.
Scope 1(PART-A)
NEW 132/33KV AIS SUBSTATION AT NAWABGANJ:
The configuration of the 132kV busbar shall be double busbar scheme.
Switchyard layout shall be designed such as to accommodate double
bus (U type) configuration.
132kV Air Insulated Switchgears (AIS):
132kV AIS switchyard for two(2) 132kV overhead line bays in order to
connect one 132kV double circuit overhead line (Keraniganj-1 & 2);
two(2) 132/33kV transformer bays for two sets of 132/33kV, 50/75MVA,
three phase transformers; one(1) bus coupler bay. Space provision with
busbar, gantry structure & switchyard finished surface without equipment
is to be kept for extension of one(1) future 132kV bays.
33kV Air Insulated Switches and Connection:
Schedule A: Requirements
SA-1
Section 1
Requirements
33kV AIS switchgear for two(2) LV side of 132/33kV power transformer
bays and one(1) 33/.415kV aux. transformer bays in order to facilitate
station power supply.
132/33kV three phase power transformer:
Two(2) sets of 50/75MVA(ONAN/ONAF), 132/33kV, three phase power
transformers.
33/0.415kV auxiliary transformer:
One (1) sets of 33/0.415kV, 200kVA, outdoor type auxiliary transformers
to supply the substation auxiliary loads.
Control, Protection, Substation Automation & Metering:
Associated control, metering, protection equipment, synchronizing
scheme and substation automation system for complete substation.
Fibre Optic Multiplexer Equipment for Communication and Protection:
Indoor type Fibre Optic Multiplexer and communication Equipment for
protection & communication and integration with existing
telecommunication communication network of PGCB.
DC and LVAC System:
Complete set of 110V DC & 48V DC and LVAC system with all
necessary materials required for the plant being installed. The system
shall be comprises with a backup/standby set.
Land Development, Civil Works, Building and Foundation:
Complete design, supply and construction of all civil items required for
land development.
Complete design, supply and construction of all civil items required for
the outdoor works suitable for switchyard gantry & equipment
foundations, transformer foundations, blast walls, oil pit, entrance &
internal roads, outdoor lighting system, cable trenches, septic tank, earth
filling, surfacing, drainage, security fences, guard house, earthing &
lightning protection, switchyard lighting, etc.
Complete design, supply and construction of all civil items including all
necessary architecture & structural requirements; cable trays, fittings and
flooring & finishes; air-conditioning and lighting for a new two storied
main control room building.
SCADA system for Telecontrol and Telemetering:
Complete design, supply, delivery, installation, testing & commissioning
of hardware and software to provide the telecontrol & telemetering
facilities required at the existing National Load Dispatch Center(NLDC) at
Aftabnagar and back up NLDC at Biddut Bhaban, for integration of
complete new 132/33kV substation. All required electrical signals shall
be transmitted to the NLDC at Aftabnagar and back up at NLDC at
Biddut Bhaban through the Industrial Gateway of the substation
automation system. All HV breakers, motorized disconnectors, tap
changer, etc. shall be controlled form NLDC through the Gateway of the
Schedule A: Requirements
SA-2
Section 1
Requirements
substation automation system using IEC 60870-5-104 protocol. All
necessary modification works in the software of master station of NLDC
and back up station at Biddut Bhabanare to be carried out.
Mandatory Spares, Maintenance tools & Test Equipment:
Supply of complete mandatory spare and spare parts of transformer,
switchgear, control equipment, protection relays, meters, maintenance
tools & test equipment. The materials shall have to be handed over to the
designated store as per instruction of the Engineer.
Scope 1(PART-B)
CONSTRUCTION OF 33KV AIS SWITCHING STATION AT
NAWABGANJ (REB PART):
The configuration of the 33kV busbar shall be single busbar scheme.
Complete outdoor type 33 kV AIS switching station consisting ten(10)
33kV overhead line bays with single busbar to accommodate two
33kV side of 132/33 kV, 50/75MVA power transformers, ten 33kV line
feeder & one (1) 33/.415kV aux. transformer bays in order to facilitate
33kV Switching station (REB Part) auxiliary power supply ;space
provision shall be kept for future extension of six(6) outgoing 33kV
bays.
One 33/0.4 kV, 200KVA outdoor type auxiliary transformers to supply
the 33kV switching station auxiliary loads.
Control, Protection & Metering:
Associated control, metering, protection equipment, synchronizing
scheme for complete switching station.
DC and LVAC System:
Complete set of 110V DC and LVAC system with all necessary
materials required for the plant being installed.
Civil Works, Building and Foundation:
Complete design, supply and construction of all civil items required for
the outdoor works suitable for switchyard gantry & equipment
foundations, entrance & internal roads, outdoor lighting system, cable
trenches, septic tank, surfacing, drainage, security fences, earthing &
lightning protection, switchyard lighting, etc.
Complete design, supply and construction of all civil items including all
necessary architecture & structural requirements; cable trays, fittings
and flooring & finishes; air-conditioning and lighting for a new 33kV
Control building etc.
Scope 2(PART-A)
Schedule A: Requirements
NEW 132/33KV AIS SUBSTATION AT SRINAGAR:
SA-3
Section 1
Requirements
The configuration of the 132kV busbar shall be double busbar scheme.
Switchyard layout shall be designed such as to accommodate double
bus (U type) configuration.
132kV Air Insulated Switchgears (AIS):
132kV AIS switchyard for two(2) 132kV overhead line bays in order to
connect one 132kV double circuit overhead line (Keraniganj PP-1 & 2);
two(2) 132/33kV transformer bays for two sets of 132/33kV, 50/75MVA,
three phase transformers; one(1) bus coupler bay. Space provision with
busbar, gantry structure & switchyard finished surface without equipment
is to be kept for extension of one(1) future 132kV bays.
33kV Air Insulated Switches and Connection:
33kV AIS switchgear for two(2) LV side of 132/33kV power transformer
bays and one(1) 33/.415kV aux. transformer bays in order to facilitate
station power supply.
132/33kV three phase power transformer:
Two(2) sets of 50/75MVA(ONAN/ONAF), 132/33kV, three phase power
transformers.
33/0.415kV auxiliary transformer:
One (1) sets of 33/0.415kV, 200kVA, outdoor type auxiliary transformers
to supply the substation auxiliary loads.
Control, Protection, Substation Automation & Metering:
Associated control, metering, protection equipment, synchronizing
scheme and substation automation system for complete substation.
Fibre Optic Multiplexer Equipment for Communication and Protection:
Indoor type Fibre Optic Multiplexer and communication Equipment for
protection & communication and integration with existing
telecommunication communication network of PGCB.
DC and LVAC System:
Complete set of 110V DC & 48V DC and LVAC system with all
necessary materials required for the plant being installed. The system
shall be comprises with a backup/standby set.
Land Development, Civil Works, Building and Foundation:
Complete design, supply and construction of all civil items required for
land development.
Complete design, supply and construction of all civil items required for
the outdoor works suitable for switchyard gantry & equipment
foundations, transformer foundations, blast walls, oil pit, entrance &
internal roads, outdoor lighting system, cable trenches, septic tank, earth
filling, surfacing, drainage, security fences, guard house, earthing &
lightning protection, switchyard lighting, etc.
Schedule A: Requirements
SA-4
Section 1
Requirements
Complete design, supply and construction of all civil items including all
necessary architecture & structural requirements; cable trays, fittings and
flooring & finishes; air-conditioning and lighting for a new two storied
main control room building.
SCADA system for Telecontrol and Telemetering:
Complete design, supply, delivery, installation, testing & commissioning
of hardware and software to provide the telecontrol & telemetering
facilities required at the existing National Load Dispatch Center(NLDC) at
Aftabnagar and back up NLDC at Biddut Bhaban, for integration of
complete new 132/33kV substation. All required electrical signals shall
be transmitted to the NLDC at Aftabnagar and back up at NLDC at
Biddut Bhaban through the Industrial Gateway of the substation
automation system. All HV breakers, motorized disconnectors, tap
changer, etc. shall be controlled form NLDC through the Gateway of the
substation automation system using IEC 60870-5-104 protocol. All
necessary modification works in the software of master station of NLDC
and back up station at Biddut Bhabanare to be carried out.
Mandatory Spares, Maintenance tools & Test Equipment:
Supply of complete mandatory spare and spare parts of transformer,
switchgear, control equipment, protection relays, meters, maintenance
tools & test equipment. The materials shall have to be handed over to the
designated store as per instruction of the Engineer.
Scope 2(PART-B)
CONSTRUCTION OF 33KV AIS SWITCHING STATION AT
SRINAGAR (REB PART):
The configuration of the 33kV busbar shall be single busbar scheme.
Complete outdoor type 33 kV AIS switching station consisting ten(10)
33kV overhead line bays with single busbar to accommodate two
33kV side of 132/33 kV, 50/75MVA power transformers, ten 33kV line
feeder & one (1) 33/.415kV aux. transformer bays in order to facilitate
33kV Switching station (REB Part) auxiliary power supply ;space
provision shall be kept for future extension of six(6) outgoing 33kV
bays.
One 33/0.4 kV, 200KVA outdoor type auxiliary transformers to supply
the 33kV switching station auxiliary loads.
Control, Protection & Metering:
Associated control, metering, protection equipment, synchronizing
scheme for complete switching station.
DC and LVAC System:
Complete set of 110V DC and LVAC system with all necessary
materials required for the plant being installed.
Schedule A: Requirements
SA-5
Section 1
Requirements
Civil Works, Building and Foundation:
Complete design, supply and construction of all civil items required for
the outdoor works suitable for switchyard gantry & equipment
foundations, entrance & internal roads, outdoor lighting system, cable
trenches, septic tank, surfacing, drainage, security fences, earthing &
lightning protection, switchyard lighting, etc.
Complete design, supply and construction of all civil items including all
necessary architecture & structural requirements; cable trays, fittings
and flooring & finishes; air-conditioning and lighting for a new 33kV
Control building etc.
Scope 3(PART-A)
NEW 132/33KV AIS SUBSTATION AT NARAIL:
The configuration of the 132kV busbar shall be single busbar scheme.
132kV Air Insulated Switchgears (AIS):
132kV AIS switchyard for two(2) 132kV overhead line bays in order to
connect one 132kV double circuit overhead line (Magura-1 & 2); two(2)
132/33kV transformer bays for two sets of 132/33kV, 50/75MVA, three
phase transformers;
33kV Air Insulated Switches and Connection:
33kV AIS switchgear for two(2) LV side of 132/33kV power transformer
bays and one(1) 33/.415kV aux. transformer bays in order to facilitate
station power supply.
132/33kV three phase power transformer:
Two(2) sets of 50/75MVA(ONAN/ONAF), 132/33kV, three phase power
transformers.
33/0.415kV auxiliary transformer:
One (1) sets of 33/0.415kV, 200kVA, outdoor type auxiliary transformers
to supply the substation auxiliary loads.
Control, Protection, & Metering:
Associated control, metering, protection equipment, synchronizing
scheme for complete substation.
Fibre Optic Multiplexer Equipment for Communication and Protection:
Indoor type Fibre Optic Multiplexer and communication Equipment for
protection & communication and integration with existing
telecommunication communication network of PGCB.
DC and LVAC System:
Schedule A: Requirements
SA-6
Section 1
Requirements
Complete set of 110V DC & 48V DC and LVAC system with all
necessary materials required for the plant being installed. The system
shall be comprises with a backup/standby set.
Land Development, Civil Works, Building and Foundation:
Complete design, supply and construction of all civil items required for
land development.
Complete design, supply and construction of all civil items required for
the outdoor works suitable for switchyard gantry & equipment
foundations, transformer foundations, blast walls, oil pit, entrance &
internal roads, outdoor lighting system, cable trenches, septic tank, earth
filling, surfacing, drainage, security fences, guard house, earthing &
lightning protection, switchyard lighting, etc.
Complete design, supply and construction of all civil items including all
necessary architecture & structural requirements; cable trays, fittings and
flooring & finishes; air-conditioning and lighting for a new two storied
main control room building.
SCADA system for Telecontrol and Telemetering:
Complete design, supply, delivery, installation, testing & commissioning
of hardwareand software to provide thetelecontrol & telemetering
facilities of complete new132/33kV substation for integration with the
existing National Load DespatchCenter(NLDC) at Aftabnagarand back
up NLDC at Biddut Bhaban. All required electrical signals shall be
transmitted to the NLDC at Aftabnagarand back up NLDC at Biddut
Bhaban through the Remote terminal units (RTU). All HV breakers,
motorizeddisconnectors etc. shall be controlled form NLDC through the
remote terminal units(RTU) using IEC 60870-5-104 protocol. New RTU
supplied under this contract shall becompetible with existing system( The
existing RTUs are AREVA, France madeMiCOM C264 type). All
necessary modification works in the software of master stationof NLDC
and back up station at Biddut Bhabanare to be carried out.
Mandatory Spares, Maintenance tools & Test Equipment:
Supply of complete mandatory spare and spare parts of transformer,
switchgear, control equipment, protection relays, meters, maintenance
tools & test equipment. The materials shall have to be handed over to the
designated store as per instruction of the Engineer.
Scope 3(PART-B)
CONSTRUCTION OF 33KV AIS SWITCHING STATION AT
NARAIL (REB PART):
The configuration of the 33kV busbar shall be single busbar scheme.
Complete outdoor type 33 kV AIS switching station consisting six(6)
33kV overhead line bays with single busbar to accommodate two
33kV side of 132/33 kV, 50/75MVA power transformers, six 33kV line
feeder & one (1) 33/.415kV aux. transformer bays in order to facilitate
Schedule A: Requirements
SA-7
Section 1
Requirements
33kV Switching station (REB Part) auxiliary power supply ;space
provision shall be kept for future extension of four(4) outgoing 33kV
bays.
One 33/0.4 kV, 200KVA outdoor type auxiliary transformers to supply
the 33kV switching station auxiliary loads.
Control, Protection & Metering:
Associated control, metering, protection equipment, synchronizing
scheme for complete switching station.
DC and LVAC System:
Complete set of 110V DC and LVAC system with all necessary
materials required for the plant being installed.
Civil Works, Building and Foundation:
Complete design, supply and construction of all civil items required for
the outdoor works suitable for switchyard gantry & equipment
foundations, entrance & internal roads, outdoor lighting system, cable
trenches, septic tank, surfacing, drainage, security fences, earthing &
lightning protection, switchyard lighting, etc.
Complete design, supply and construction of all civil items including all
necessary architecture & structural requirements; cable trays, fittings
and flooring & finishes; air-conditioning and lighting for a new 33kV
Control building etc.
Scope 4
Extension of existing 132/33kV AIS Substation at Jhenaidaha:
The configuration of the existing 132kV busbar is double bus
arrangement and consists of six (6) line bays, two (2) transformer bays
and a bus tie bay. The complete new 132kV bay equipment shall be
installed for one bay extension to connect Magura-2nd 132kV circuit.
132kV Air Insulated Switchgears (AIS):
132kV AIS switchyard for extension of new one(1) 132kV overhead line
bays in order to connect 132kV overhead line (Magura- 2).
Control, Protection, & Metering:
Associated control, metering, protection equipment, synchronizing
scheme for new one(1) 132kV overhead line bays.
Fibre Optic Multiplexer Equipment for Communication and Protection:
Extension of existing Fibre Optic Multiplexer and communication
equipment for protection & communication shall be caried out by the
contractor of this contract. The existing Fiber optic multiplexer and
communication equipment is AREVA, France made MSE 5001 type.
DC and LVAC System:
Schedule A: Requirements
SA-8
Section 1
Requirements
Extension of existing DCDB & LVAC system by necessary materials
required for the plant being installed.
Civil Works, Building and Foundation:
Complete design, supply and construction of all civil items required for
the outdoor works suitable for switchyard gantry & equipment
foundations, internal roads, outdoor lighting system, cable trenches,
surfacing, drainage, security fences, earthing & lightning protection, etc
to accommodate new bays.
SCADA system for Telecontrol and Telemetering:
Complete design, supply, delivery, installation, testing & commissioning
of hardware and software to provide the telecontrol & telemetering
facilities required at the existing National Load Despatch Center (NLDC)
at Aftabnagarand back up station at Biddut Bhabanfor integration of one
new 132kV line bays. All required electrical signals shall be transmitted
to the NLDC at Aftabnagar and back up station at Biddut Bhabanthrough
the Remote terminal units (RTU). All HV breakers, motorized
disconnectors etc. shall be controlled form NLDC through the remote
terminal units (RTU) using IEC 60870-5-104 protocol. All necessary
modification works in the software of master station of NLDC and back
up station at Biddut Bhabanare to be carried out. The existing RTUs are
AREVA, France made MiCOM C264 type.
Scope 5
Extension of existing 132/33kV AIS Substation at Magura:
The configuration of the existing 132kV busbar is main and transfer bus
arrangement and consists of one (1) line bays, two(2) transformer bays
and a bus tie bay. Three(3)complete new 132kV bay equipment shall be
installed for three(3) bay extension to connect Jhenaidaha-2nd 132kV
circuit and Narail(1 & 2) 132kV circuit.
132kV Air Insulated Switchgears (AIS):
132kV AIS switchyard for extension of new three(3) 132kV overhead line
bays in order to connect 132kV overhead line Jhenaidaha-2, and Narail(1
& 2).
Control, Protection, & Metering:
Associated control, metering, protection equipment, synchronizing
scheme for new three(3) 132kV overhead line bays.
Fibre Optic Multiplexer Equipment for Communication and Protection:
Extension of existing Fibre Optic Multiplexer and communication
equipment for protection & communication shall be caried out by the
contractor of this contract. The existing Fiber optic multiplexer and
communication equipment is AREVA, France made MSE 5001 type.
DC and LVAC System:
Extension of existing DCDB & LVAC system by necessary materials
required for the plant being installed.
Schedule A: Requirements
SA-9
Section 1
Requirements
Civil Works, Building and Foundation:
Complete design, supply and construction of all civil items required for
the outdoor works suitable for switchyard gantry & equipment
foundations, internal roads, outdoor lighting system, cable trenches,
surfacing, drainage, security fences, earthing & lightning protection, etc
to accommodate new bays.
SCADA system for Telecontrol and Telemetering:
Complete design, supply, delivery, installation, testing & commissioning
of hardware and software to provide the telecontrol & telemetering
facilities required at the existing National Load Despatch Center (NLDC)
at Aftabnagarand back up station at Biddut Bhabanfor integration of three
new 132kV line bays. All required electrical signals shall be transmitted
to the NLDC at Aftabnagar and back up station at Biddut Bhabanthrough
the Remote terminal units (RTU). All HV breakers, motorized
disconnectors etc. shall be controlled form NLDC through the remote
terminal units (RTU) using IEC 60870-5-104 protocol. All necessary
modification works in the software of master station of NLDC and back
up station at Biddut Bhabanare to be carried out. The existing RTUs are
AREVA, France made MiCOM C264 type.
Schedule A: Requirements
SA-10
Section 1
Requirements
A2.DESCRIPTION OF THE WORKS FOR PRICE SCHEDULE
SCOPE-1(PART-A):Nawabganj132/33kV AIS Substation:
The equipment to be designed, supplied, installed, tested & commissioned asper detail technical
specification and as shown in bid drawings (volume 2 of 2 of this bid document):
Item
Description
1.1A
132 kV Air Insulated Switchgear (AIS)
The 145kV AIS shall comply with the particular requirements as detailed in the Schedule
of Technical Requirements included as Appendix A3 to this section and shall comprise the
following:-
1.1A.1
One(1) set of 132kV, 2000A, 40kA/3sec, 50Hz, 650kVp BIL, live tank type, gang operated,
SF6 gas circuit breaker with spring-stored energy operating mechanism (for bus coupler).
1.1A.2
Two(2) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL, live tank type, gang
operated, SF6 gas circuit breaker with spring-stored energy operating mechanism (for
Transformer bays).
1.1A.3
Two(2) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL, live tank type, single pole
operated, SF6 gas circuit breaker with spring-stored energy operating mechanism (for
Transsmission line bays).
1.1A.4
Two(2) sets of 132kV, 2000A, 40kA/3sec, 50Hz, 650kVp BIL,double side break, post type,
motor operated disconnectors with manual earthing switch (for bus coupler).
1.1A.5
Four(4) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL,double side break, post type,
motor operated disconnectors with manual earthing switch.
1.1A.6
Eight(8) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL, double side break, post
type, motor operated disconnectors without earthing switch.
1.1A.7
Six(6) nos. of single-phase, 2-core, multi ratio, 132kV, 40kA/3sec, 50Hz, 650kVp BIL, post
type current transformer (for bus coupler bay, 2000/1A).
1.1A.8
Six (6) nos. of single-phase, 4-core, multi ratio, 132kV, 40kA/3sec, 50Hz, 650kVp BIL, post
type current transformer(for line bays).
1.1A.9
Six(6) nos. of single-phase, 4-core, multi ratio, 132kV, 40kA/3sec, 50Hz, 650kVp BIL, post
type current transformer(for Transformer bays).
1.1A.10
Eighteen (18) nos. of single-phase, 2-core, 132kV, 40kA/3sec, 50Hz, 650kVp BIL,
Inductive voltage transformers (IVT).
Schedule A: Requirements
SA-11
Section 1
Requirements
1.1A.11
Twelve(12) nos. of 120kV rated voltage, 102kV(rms) continuous operating voltage at
500c, 10kA nominal discharge current, 50Hz, Heavy duty station class, gapless metal
oxide type, single phase surge arresters.
1.1A.12
Six(6) nos. single phase 145kV post type support insulators required for completing 145kV
busbar and switchgear connections.
1.1A.13
One(1) lot of flexible conductors for busbar [ACSR] & jackbus, jumper, equipment
connections [ACSR, Single Grosbeak (636 MCM)], including all necessary clamps &
connectors required for completing 132kV busbar and switchgear connection.
1.1A.14
One (1) lot of disc insulators and fittings including all necessary accessories required to
complete 132kV switchyard
1.1A.15
One(1) lot of steel structures for gantry and equipment supports including nuts & bolts and
cable tray including all necessary fitting & fixing accessories required to complete 132kV
switchyard.
1.1B
33kV Air Insulated Switches and Connectionfor Auxiliary Transformers
The 33kV AIS shall comply with the particular requirements as detailed in the Schedule of
Technical Requirements included as Appendix A3 to this section andshall comprise the
following:-
1.1B1
Two (2) sets of 33kV, 2500A, 31.5kA/3sec, 50Hz, 170kVp BIL, outdoor Vacuum Circuit
Breakers(VCB) with spring-stored energy operating mechanism.
1.1B2
Four (4) sets of 33kV, 2500A, 31.5kA/3sec, 50Hz, 170kVp BIL, single vertical break, post
type, disconnectors.
1.1B3
Six(6) nos. of single-phase, 3-core, multi ratio, 33kV, 31.5kA/3sec, 50Hz, 170kVp BIL, post
type current transformer.
1.1B4
Six(6) nos. of single-phase, 2-core, 33kV, 31.5kA/3sec, 50Hz, 170kVp BIL, voltage
transformers.
1.1B5
Six(6) nos. of 30kV rated voltage, 10kA nominal discharge current, 50Hz, Heavy duty
station class, single phase surge arresters.
1.1B6
One (1) lot of flexible conductors for jack bus, jumper, equipment connections [ACSR
Conductor], including all necessary clamps & connectors required for connection of 33kV
side of 132/33kV transformer with 33kV bus bar and switchgear connection.
1.1B7
One (1) lot of insulators and fittings including all necessary accessories required to
complete 33kV connection of 33kV incomer side of 132/33kV transformer with 33kV bus.
1.1B8
One (1) lot of steel structures for equipment supports including nuts & bolts and cable tray
including all necessary fitting & fixing accessories required for completing 33kV incomer
Schedule A: Requirements
SA-12
Section 1
Requirements
side of 132/33kV transformer with 33kV bus.
1.1B9
One (1) sets of 33kV, 200A rated outdoor fuse disconnecting switch for station auxiliary
transformer feeder (three phase, 3pole gang manual operated, 10A power fuse, structure
mounted) as shown on the relevant bid drawings.
1.1C
1.1C1
Power Transformers& Earthing/Auxiliary Transformers
Two (2) sets of 132/33kV, 50/75 MVA (ONAN/ONAF), three phase outdoor type power
transformers with associated bushing CTs including all necessary connections, insulators
& fittings.
1.1C2
One(1) sets 33/0.415kV, 200kVA three phase outdoor type station auxiliary transformers
with associated steel support structures including all necessary connections, insulators &
fittings.
1.1C3
Nitrogen injection Fire protection system for two (2) 132/33kV power transformer complete
One (01) lot.
1.1D
Control, Protection, Substation Automation & Metering
132 kV Circuits
The equipment to be designed, supplied, installed and commissioned is shown in bid
drawings are comprising of :-
1.1D1
Control, Protection, Metering & Substation Automation System including event recording
function for two (2) sets of overhead line circuits to Keraniganj-1 & 2.
1.1D2
Control, Protection, Metering & Substation Automation System including event recording
function for two(2) sets of 132/33 kV power transformer circuits including transformer tap
changer control.
1.1D3
Control, Protection, metering & Substation Automation System including event recording
function for one(1) set of bus coupler circuit.
1.1D4
Tariff metering panel to accommodate programmable & recordable digital 3-phase, 4-wire
import and export MWh and MVArhmeters (accuracy class 0.2) for two(2) 132 kV line and
two(2) transformer feeder. For each feeder minimum two meters (main & check). The
scope of works also includes supply of software(s) & connection cords of the above
energy meters for future re-configuration.
33 kV Circuits
The equipment to be supplied, installed and commissioned is shown in bid drawings are
comprising of:-
1.1D5
Control, Protection, Metering & Substation Automation System including event recording
function for two sets of power transformer incommer circuits.
1.1D6
Tariff metering panel to accommodate programmable & recordable digital 3-phase, 4-wire
import and export MWh and MVArhmeters (accuracy class 0.2) for two transformer feeder
circuits (Power X-former-I & II). For each feeder minimum two meters (main & check). The
Schedule A: Requirements
SA-13
Section 1
Requirements
scope of works also includes supply of software(s) of the above energy meters for future
re-configuration.
1.1E
1.1E1
Multicore Cables
One (1) lot complete set of multicore low voltage 0.6/1.1kV, XLPE insulated power and
control cables (IEC 60502) shall be supplied, installed, glanded, terminated and have
individual cores identified to be used for connection of all equipment supplied under the
Contract. The overall substation cable routing and core schedules shall also be provided.
1.1F
Earthing and Lightning Protection
1.1F1
One(1) lot of design, supply and installation of earthing system and lightning protection
screen including connections, connectors and clamps, to suit the substation overall
arrangement and provide supporting design calculations.
1.1F2
One(1) set of 3-phase portable (maintenance) earthing equipment devices with connectors
and telescopic glass fibre operating pole suitable for plant supplied.
1.1G
Batteries, Chargers and DC Distribution
1.1G1
110V substation NiCad batteries complete with chargers and distribution switchboard
to be supplied, installed and commissioned to provide all DC supplies to equipment
being supplied.
The system shall generally be as shown in bid drawing and shall include:
i)
Two (2) sets of 100% batteries complete, each capacity shall not be less than 250Ah
at the 5-hour rate of discharge.
ii)
Two (2) sets of battery chargers complete, each charger shall not be less than 75A
rating.
iii) One (1) set of DC distribution board. The DC distribution board shall be with 50%
overall spare MCB’s for future use.
iv) Two (2) sets of online UPS, 3kVA for Substation Automation system panels.
v)
Two (2) sets of DC/DC Converter 110/48V, 1kVA for communication panels.
vi) One (1) set of 48V DC distribution board. The DC distribution board shall be with 50%
spare MCBs for future use.
1.1H
1.1H1
1.1H2
LVAC Distribution
One(1) lot of LVAC switchboard for substation services to be supplied, installed and
commissioned, to provide the 415/240V supplies to all equipment being supplied under
this turnkey Bid.
One(1) lot of Tariff metering to accommodate programmable & recordable digital 3-phase,
4-wire import and export MWh and MVArhmeters (accuracy class 0.2) for one 33/0.415 kV
station auxiliary transformer feeder circuits. For each feeder minimum two meters (main &
Schedule A: Requirements
SA-14
Section 1
Requirements
check).
1.1H3
One (1) nos. 125A outdoor weatherproof 3-phase with neutral and earth switched socket
outlet and plug as per IEC 309; to be installed, cabled and connected adjacent to the
132/33kV Power Transformer.
1.1I
Civil Works, Building and Foundation
1.1I1
Complete earth filling by imported carried earth free from foreign solid particles and
organic materials in addition to the earth recovered from digging of foundation, to make
the top of the final ground level of substation 0.5m high from highest flood level and final
compaction to be achieved 95% for total volume 60,800 cubic meter. The volume of earth
filling may be varied but the payment shall be as per actual measurement of work done.
1.1I2
One(1) lot of complete design, supply and construction of all civil items required for the
outdoor works suitable for switchyard gantry & equipment foundations, transformer
foundations, blast walls, oil pit, entrance & internal roads, cable trenches, septic tank, soak
way, surfacing, gravel laying, drainage, security fences, boundary wall, sentry post, guard
house, car port, etc.
1.1I3
One(1) lot of complete design, supply and construction of all civil items and facilities
required for the two storied main control building including cable basement.
1.1J
1.1J1
Lighting, Small Power, Air Conditioning and Ventilation
One(1) lot of complete design, supply, installation and commissioning of equipment to
provide lighting, LV power supply, air conditioning system, ventilation system and
emergency DC lighting for the main control building.
1.1J2
One(1) lot of complete set of design, supply, installation and commissioning of equipment
to provide lighting (flood light LED type) for security, roadway, switchyard and emergency
DC lighting at strategic locations for equipment operation and inspection.
1.1K
One (1) lot of complete CCTV camera system (8 nos. Camera) for Main control building
including switchyard area with NVR and other required accessories.
1.1L
1.1L1
Fibre Optic Multiplexer Equipment for Communication and Protection
The equipment to be supplied, installed and commissioned shall be as shown on bid
drawing. One(1) lot complete set of design, supply, installation and commissioning of fibre
optic multiplexer equipment including necessary works to interface with existing system is
to be provided for:
- 87 or 21 relay for each transmission line protection (through fibre cores)
- 21 relay carrier signal (main and back-up)
- SCADA data from switchgear and control system
- hot-line telephone system
1.1L2
Underground optical fibre cables (24cores for 132kV switchyard) from terminal box gantry
structure at each 132kV double circuit transmission line termination point to MDF (Main
Schedule A: Requirements
SA-15
Section 1
Requirements
distribution Frame) to be installed in control room. The Contract includes supply and
installation of MDF and pigtail cables with adequate length.
1.1M
1.1M1
SCADA system for Telecontrol and Telemetering
Complete design, supply, delivery, installation, testing & commissioning of hardware and
software to provide the telecontrol & telemetering facilities required at the existing
National Load Dispatch Center(NLDC) at Aftabnagar and back up NLDC at Biddut
Bhaban, for integration of complete new 132/33kV substation. All required electrical
signals shall be transmitted to the NLDC at Aftabnagar and back up at NLDC at Biddut
Bhaban through the Industrial Gateway of the substation automation system. All HV
breakers, motorized disconnectors, tap changer, etc. shall be controlled form NLDC
through the Gateway of the substation automation system using IEC 60870-5-104
protocol. All necessary modification works in the software of master station of NLDC and
back up station at Biddut Bhabanare to be carried out.
1.1N
Mandatory Spares, Erection & Test Equipment
Supply of complete spares and spare parts of transformer, switchgear, control equipment,
protection relays, meters, erection & test equipment as per quantity mentioned in
Schedule B. Test equipment are to be supplied from Europe, USA or Japan origin. Printed
catalogue, operation and service manual are to be provided. The materials shall have to
be handed over to the designated store as per instruction of the Engineer.
SCOPE-1(PART_B): 33kV AIS Switching Station (REB Part):
The equipment to be designed, supplied, installed, tested & commissioned as per detail
technical specification and as shown in bid drawings (volume 1 of 2 of this bid document):
Item
Description
1.2A
33kV Air Insulated Switchgear (AIS) and Connection:
The 33kV AIS shall comply with the particular requirements as detailed in the
Schedule of Technical Requirements included as Appendix A3 to this section
and bid drawings; shall comprise the following:-
1.2A1
Ten (10) sets of 33kV, 1250A, 31.5kA/3sec, 50Hz, 170kVp BIL, outdoor
Vacuum Circuit Breakers (VCB) with spring-stored energy operating
mechanism.
1.2A2
Ten(10) sets of 33kV, 1250A, 31.5kA/3sec, 50Hz, 170kVp BIL, single
vertical break, post type, disconnectors without earth switch.
1.2A3
Ten (10) sets of 33kV, 1250A, 31.5kA/3sec, 50Hz, 170kVp BIL, single
vertical break, post type, disconnectors with earth switch.
Schedule A: Requirements
SA-16
Section 1
Requirements
1.2A4
One(1) sets of 33kV, 2500A, 31.5kA/3sec, 50Hz, 170kVp BIL, single vertical
break, post type, disconnectors.
1.2A5
One (1) sets of 36kV, 200A rated outdoor fuse disconnecting switch for station auxiliary
transformer feeder (three phase, 3pole gang manual operated, 10A power fuse, structure
mounted) as shown on the relevant bid drawings.
1.2A6
Thirty(30) nos. of single-phase, 3-core, multi ratio, 36kV, 31.5kA/3sec, 50Hz,
170kVp BIL, post type current transformer.
1.2A7
Thirty six(36) nos. of single-phase, 2-core, 36kV, 31.5kA/3sec, 50Hz, 170kVp
BIL, voltage transformers.
1.2A8
Thirty (30) nos. of 30kV rated voltage, 10kA nominal discharge current,
50Hz, Heavy duty station class, single phase surge arresters.
1.2A9
One(1) lot of flexible conductors for busbar, jackbus, jumper, equipment
connections[ACSR conductor], including all necessary clamps & connectors
required for completing 33kV busbar and switchgear connection.
1.2A10
One(1) lot of insulators and fittings including all necessary accessories
required to complete 33kV switchyard.
1.2A11
One(1) lot of steel structures for gantry and equipment supports including nuts
& bolts and cable tray including all necessary fitting & fixing accessories
required for completing 33kV switchyard.
1.2B
Auxiliary Transformers
1.2B1
One(1) sets 33/0.415kV, 200kVA three phase outdoor type station auxiliary
transformers with associated support steel structures including all necessary
connections, insulators & fittings.
1.2C
Control, Protection & Metering 33 kV Circuits
The equipment to be supplied, installed and commissioned shall be as shown
in bid drawings and comprise of:-
1.2C1
Control, Protection &Metering forten(10) outgoing line circuits.
1.2C2
Tariff metering panel to accommodate programmable & recordable digital 3phase, 4-wire import and export MWh and MVArh meters (accuracy class
0.2) for ten line feeder circuits. For each feeder minimum two meters (main &
check).
Multicore Cables
1.2D
Schedule A: Requirements
SA-17
Section 1
Requirements
1.2D1
One(1) lot complete set of multicore low voltage 0.6/1.1kV, XLPE insulated
power and control cables (IEC 60502) shall be supplied, installed, glanded,
terminated and have individual cores identified to be used for connection of
all equipment supplied under this Contract. The overall switching station
cable routing and core schedules shall also be provided.
1.2E
Earthing and Lightning Protection
1.2E1
One(1) lot of design, supply and installation of earthing system and lightning
protection screen including connections, connectors and clamps, to suit the
substation overall arrangement and provide supporting design calculations for
33kV switching station.
1.2F
Batteries, Chargers and DC Distribution
1.2F1
110V substation NiCad batteries complete with chargers and distribution
switchboard to be supplied, installed and commissioned to provide all DC
supplies to equipment being supplied.
The system shall generally be as shown in bid drawing and shall include:
(a) Two (2) sets of 100% batteries complete, each capacity shall not be less than
150Ah at the 5-hour rate of discharge.
(b) Two (2) sets of battery chargers complete, each charger shall not be less than
50A rating.
(c) One (1) set of DC distribution board. The DC distribution board shall be with
50% spare MCBs for future use.
1.2G
LVAC Distribution
1.2G1
One (1) lot of LVAC switchboard for switching station services to be
supplied, installed and commissioned, to provide the 415/240V supplies to all
equipment being supplied under this bid.
1.2G2
One (1) lot of Tariff metering to accommodate programmable & recordable
digital 3-phase, 4-wire import and export MWh and MVArh meters (accuracy
class 0.2) for one 33/0.415 kV station auxiliary transformer feeder circuits.
For each feeder minimum two meters (main & check).
1.2H
Civil Works, Building and Foundation
1.2H1
Complete earth filling by imported earth free from foreign solid particles and
organic materials in addition to the earth recovered from digging of
foundation, to make the top of the final ground level of substation 3.0m high
from highest flood level and final compaction to be achieved 95% for total
volume 5000 cubic meter. The quantity of earth filling has been specified in
Schedule A: Requirements
SA-18
Section 1
Requirements
the price schedule, which may vary and will be finalized during detail
engineering. The payment shall be made as per actual measurement of work
done.
1.2H2
One(1) lot of complete design, supply and construction of all civil items
required for the outdoor works suitable for switchyard gantry & equipment
foundations, entrance & internal roads, cable trenches, septic tank, soak way,
surfacing, gravel laying, drainage, security fences, retaining wall etc. The
quantity of retaining wall has been specified in the price schedule, which may
vary and will be finalized during detail engineering. The payment shall be
made as per actual measurement of work done.
1.2H3
One (1) lot of complete design, supply and construction of all civil items and
facilities required for the twostoried control building.
1.2I
Lighting, Small Power, Air Conditioning and Ventilation
1.2I1
One (1) lot of complete design, supply, installation and commissioning of
equipment to provide lighting, LV power supply, air conditioning system,
ventilation system and emergency DC lighting for the control building.
1.2I2
One (1) lot of complete set of design, supply, installation and commissioning
of equipment to provide lighting (flood light LED type) for security, roadway,
switchyard and emergency DC lighting at strategic locations of 33kV
switching station for equipment operation and inspection.
1.2J
Mandatory Spares, Erection & Test Equipment
Supply of complete spares and spare parts of switchgear, control equipment,
protection relays, meters, erection & test equipment as per quantity mentioned
in schedules of rates and prices. Printed catalogue, operation and service
manual are to be provided for supplied test equipment. The materials shall
have to be handed over to the designated store as per instruction of the
Employer’s Engineer.
Schedule A: Requirements
SA-19
Section 1
Requirements
SCOPE-2(PART-A):Srinagar 132/33kV AIS Substation:
The equipment to be designed, supplied, installed, tested & commissioned as per detail technical
specification and as shown in bid drawings (volume 2 of 2 of this bid document):
Item
Description
2.1A
132 kV Air Insulated Switchgear (AIS)
The 145kV AIS shall comply with the particular requirements as detailed in the Schedule
of Technical Requirements included as Appendix A3 to this section and shall comprise the
following:-
2.1A.1
One(1) set of 132kV, 2000A, 40kA/3sec, 50Hz, 650kVp BIL, live tank type, gang operated,
SF6 gas circuit breaker with spring-stored energy operating mechanism (for bus coupler).
2.1A.2
Two(2) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL, live tank type, gang
operated, SF6 gas circuit breaker with spring-stored energy operating mechanism (for
Transformer bays).
2.1A.3
Two(2) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL, live tank type, single pole
operated, SF6 gas circuit breaker with spring-stored energy operating mechanism (for
Transsmission line bays).
2.1A.4
Two(2) sets of 132kV, 2000A, 40kA/3sec, 50Hz, 650kVp BIL,double side break, post type,
motor operated disconnectors with manual earthing switch (for bus coupler).
2.1A.5
Four(4) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL,double side break, post type,
motor operated disconnectors with manual earthing switch.
2.1A.6
Eight(8) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL, double side break, post
type, motor operated disconnectors without earthing switch.
2.1A.7
Six(6) nos. of single-phase, 2-core, multi ratio, 132kV, 40kA/3sec, 50Hz, 650kVp BIL, post
type current transformer (for bus coupler bay, 2000/1A).
2.1A.8
Six (6) nos. of single-phase, 4-core, multi ratio, 132kV, 40kA/3sec, 50Hz, 650kVp BIL, post
type current transformer(for line bays).
2.1A.9
Six(6) nos. of single-phase, 4-core, multi ratio, 132kV, 40kA/3sec, 50Hz, 650kVp BIL, post
type current transformer(for Transformer bays).
2.1A.10
Eighteen (18) nos. of single-phase, 2-core, 132kV, 40kA/3sec, 50Hz, 650kVp BIL,
Inductive voltage transformers (IVT).
2.1A.11
Twelve(12) nos. of 120kV rated voltage, 102kV(rms) continuous operating voltage at
500c, 10kA nominal discharge current, 50Hz, Heavy duty station class, gapless metal
oxide type, single phase surge arresters.
Schedule A: Requirements
SA-20
Section 1
Requirements
2.1A.12
Six(6) nos. single phase 145kV post type support insulators required for completing 145kV
busbar and switchgear connections.
2.1A.13
One(1) lot of flexible conductors for busbar [ACSR] & jackbus, jumper, equipment
connections [ACSR, Single Grosbeak (636 MCM)], including all necessary clamps &
connectors required for completing 132kV busbar and switchgear connection.
2.1A.14
One (1) lot of disc insulators and fittings including all necessary accessories required to
complete 132kV switchyard
2.1A.15
One(1) lot of steel structures for gantry and equipment supports including nuts & bolts and
cable tray including all necessary fitting & fixing accessories required to complete 132kV
switchyard.
2.1B
33kV Air Insulated Switches and Connectionfor Auxiliary Transformers
The 33kV AIS shall comply with the particular requirements as detailed in the Schedule of
Technical Requirements included as Appendix A3 to this section andshall comprise the
following:-
2.1B1
Two (2) sets of 33kV, 2500A, 31.5kA/3sec, 50Hz, 170kVp BIL, outdoor Vacuum Circuit
Breakers(VCB) with spring-stored energy operating mechanism.
2.1B2
Four (4) sets of 33kV, 2500A, 31.5kA/3sec, 50Hz, 170kVp BIL, single vertical break, post
type, disconnectors.
2.1B3
Six(6) nos. of single-phase, 3-core, multi ratio, 33kV, 31.5kA/3sec, 50Hz, 170kVp BIL, post
type current transformer.
2.1B4
Six(6) nos. of single-phase, 2-core, 33kV, 31.5kA/3sec, 50Hz, 170kVp BIL, voltage
transformers.
2.1B5
Six(6) nos. of 30kV rated voltage, 10kA nominal discharge current, 50Hz, Heavy duty
station class, single phase surge arresters.
2.1B6
One (1) lot of flexible conductors for jack bus, jumper, equipment connections [ACSR
Conductor], including all necessary clamps & connectors required for connection of 33kV
side of 132/33kV transformer with 33kV bus bar and switchgear connection.
2.1B7
One (1) lot of insulators and fittings including all necessary accessories required to
complete 33kV connection of 33kV incomer side of 132/33kV transformer with 33kV bus.
2.1B8
One (1) lot of steel structures for equipment supports including nuts & bolts and cable tray
including all necessary fitting & fixing accessories required for completing 33kV incomer
side of 132/33kV transformer with 33kV bus.
2.1B9
One (1) sets of 33kV, 200A rated outdoor fuse disconnecting switch for station auxiliary
transformer feeder (three phase, 3pole gang manual operated, 10A power fuse, structure
mounted) as shown on the relevant bid drawings.
Schedule A: Requirements
SA-21
Section 1
Requirements
2.1C
2.1C1
Power Transformers& Earthing/Auxiliary Transformers
Two (2) sets of 132/33kV, 50/75 MVA (ONAN/ONAF), three phase outdoor type power
transformers with associated bushing CTs including all necessary connections, insulators
& fittings.
2.1C2
One(1) sets 33/0.415kV, 200kVA three phase outdoor type station auxiliary transformers
with associated steel support structures including all necessary connections, insulators &
fittings.
Nitrogen injection Fire protection system for two (2) 132/33kV power transformer complete
One (01) lot.
2.1C3
2.1D
Control, Protection, Substation Automation & Metering
132 kV Circuits
The equipment to be designed, supplied, installed and commissioned is shown in bid
drawings are comprising of :-
2.1D1
Control, Protection, Metering & Substation Automation System including event recording
function for two (2) sets of overhead line circuits to Keraniganj-1 & 2.
2.1D2
Control, Protection, Metering & Substation Automation System including event recording
function for two(2) sets of 132/33 kV power transformer circuits including transformer tap
changer control.
2.1D3
Control, Protection, metering & Substation Automation System including event recording
function for one(1) set of bus coupler circuit.
2.1D4
Tariff metering panel to accommodate programmable & recordable digital 3-phase, 4-wire
import and export MWh and MVArhmeters (accuracy class 0.2) for two(2) 132 kV line and
two(2) transformer feeder. For each feeder minimum two meters (main & check). The
scope of works also includes supply of software(s) & connection cords of the above
energy meters for future re-configuration.
33 kV Circuits
The equipment to be supplied, installed and commissioned is shown in bid drawings are
comprising of:-
2.1D5
Control, Protection, Metering & Substation Automation System including event recording
function for two sets of power transformer incommer circuits.
2.1D6
Tariff metering panel to accommodate programmable & recordable digital 3-phase, 4-wire
import and export MWh and MVArhmeters (accuracy class 0.2) for two transformer feeder
circuits (Power X-former-I & II). For each feeder minimum two meters (main & check). The
scope of works also includes supply of software(s) of the above energy meters for future
re-configuration.
2.1E
2.1E1
Multicore Cables
One (1) lot complete set of multicore low voltage 0.6/1.1kV, XLPE insulated power and
control cables (IEC 60502) shall be supplied, installed, glanded, terminated and have
Schedule A: Requirements
SA-22
Section 1
Requirements
individual cores identified to be used for connection of all equipment supplied under the
Contract. The overall substation cable routing and core schedules shall also be provided.
2.1F
Earthing and Lightning Protection
2.1F1
One(1) lot of design, supply and installation of earthing system and lightning protection
screen including connections, connectors and clamps, to suit the substation overall
arrangement and provide supporting design calculations.
2.1F2
One(1) set of 3-phase portable (maintenance) earthing equipment devices with connectors
and telescopic glass fibre operating pole suitable for plant supplied.
2.1G
Batteries, Chargers and DC Distribution
2.1G1
110V substation NiCad batteries complete with chargers and distribution switchboard
to be supplied, installed and commissioned to provide all DC supplies to equipment
being supplied.
The system shall generally be as shown in bid drawing and shall include:
vii) Two (2) sets of 100% batteries complete, each capacity shall not be less than 250Ah
at the 5-hour rate of discharge.
viii) Two (2) sets of battery chargers complete, each charger shall not be less than 75A
rating.
ix) One (1) set of DC distribution board. The DC distribution board shall be with 50%
overall spare MCB’s for future use.
x)
Two (2) sets of online UPS, 3kVA for Substation Automation system panels.
xi) Two (2) sets of DC/DC Converter 110/48V, 1kVA for communication panels.
xii) One (1) set of 48V DC distribution board. The DC distribution board shall be with 50%
spare MCBs for future use.
2.1H
2.1H1
2.1H2
LVAC Distribution
One(1) lot of LVAC switchboard for substation services to be supplied, installed and
commissioned, to provide the 415/240V supplies to all equipment being supplied under
this turnkey Bid.
One(1) lot of Tariff metering to accommodate programmable & recordable digital 3-phase,
4-wire import and export MWh and MVArhmeters (accuracy class 0.2) for one 33/0.415 kV
station auxiliary transformer feeder circuits. For each feeder minimum two meters (main &
check).
Schedule A: Requirements
SA-23
Section 1
Requirements
2.1H3
One (1) nos. 125A outdoor weatherproof 3-phase with neutral and earth switched socket
outlet and plug as per IEC 309; to be installed, cabled and connected adjacent to the
132/33kV Power Transformer.
2.1I
Civil Works, Building and Foundation
2.1I1
Complete earth filling by imported carried earth free from foreign solid particles and
organic materials in addition to the earth recovered from digging of foundation, to make
the top of the final ground level of substation 0.5m high from highest flood level and final
compaction to be achieved 95% for total volume 60,800 cubic meter. The volume of earth
filling may be varied but the payment shall be as per actual measurement of work done.
2.1I2
One(1) lot of complete design, supply and construction of all civil items required for the
outdoor works suitable for switchyard gantry & equipment foundations, transformer
foundations, blast walls, oil pit, entrance & internal roads, cable trenches, septic tank, soak
way, surfacing, gravel laying, drainage, security fences, boundary wall, sentry post, guard
house, car port, etc.
2.1I3
One(1) lot of complete design, supply and construction of all civil items and facilities
required for the two storied main control building including cable basement.
2.1J
2.1J1
Lighting, Small Power, Air Conditioning and Ventilation
One(1) lot of complete design, supply, installation and commissioning of equipment to
provide lighting, LV power supply, air conditioning system, ventilation system and
emergency DC lighting for the main control building.
2.1J2
One(1) lot of complete set of design, supply, installation and commissioning of equipment
to provide lighting (flood light LED type) for security, roadway, switchyard and emergency
DC lighting at strategic locations for equipment operation and inspection.
2.1K
One (1) lot of complete CCTV camera system (8 nos. Camera) for main control building
including switchyard area with NVR and other required accessories.
2.1L
2.1L1
Fibre Optic Multiplexer Equipment for Communication and Protection
The equipment to be supplied, installed and commissioned shall be as shown on bid
drawing. One(1) lot complete set of design, supply, installation and commissioning of fibre
optic multiplexer equipment including necessary works to interface with existing system is
to be provided for:
- 87 or 21 relay for each transmission line protection (through fibre cores)
- 21 relay carrier signal (main and back-up)
- SCADA data from switchgear and control system
- hot-line telephone system
2.1L2
Underground optical fibre cables (24cores for 132kV switchyard) from terminal box gantry
structure at each 132kV double circuit transmission line termination point to MDF (Main
distribution Frame) to be installed in control room. The Contract includes supply and
installation of MDF and pigtail cables with adequate length.
Schedule A: Requirements
SA-24
Section 1
Requirements
2.1M
2.1M1
SCADA system for Telecontrol and Telemetering
Complete design, supply, delivery, installation, testing & commissioning of hardware and
software to provide the telecontrol & telemetering facilities required at the existing
National Load Dispatch Center(NLDC) at Aftabnagar and back up NLDC at Biddut
Bhaban, for integration of complete new 132/33kV substation. All required electrical
signals shall be transmitted to the NLDC at Aftabnagar and back up at NLDC at Biddut
Bhaban through the Industrial Gateway of the substation automation system. All HV
breakers, motorized disconnectors, tap changer, etc. shall be controlled form NLDC
through the Gateway of the substation automation system using IEC 60870-5-104
protocol. All necessary modification works in the software of master station of NLDC and
back up station at Biddut Bhabanare to be carried out.
2.1N
Mandatory Spares, Erection & Test Equipment
Supply of complete spares and spare parts of transformer, switchgear, control equipment,
protection relays, meters, erection & test equipment as per quantity mentioned in
Schedule B. Test equipment are to be supplied from Europe, USA or Japan origin. Printed
catalogue, operation and service manual are to be provided. The materials shall have to
be handed over to the designated store as per instruction of the Engineer.
SCOPE-2(PART_B): 33kV AIS Switching Station (REB Part):
The equipment to be designed, supplied, installed, tested & commissioned as per detail
technical specification and as shown in bid drawings (volume 1 of 2 of this bid document):
Item
Description
2.2A
33kV Air Insulated Switchgear (AIS) and Connection:
The 33kV AIS shall comply with the particular requirements as detailed in the
Schedule of Technical Requirements included as Appendix A3 to this section
and bid drawings; shall comprise the following:-
2.2A1
Ten (10) sets of 33kV, 1250A, 31.5kA/3sec, 50Hz, 170kVp BIL, outdoor
Vacuum Circuit Breakers (VCB) with spring-stored energy operating
mechanism.
2.2A2
Ten(10) sets of 33kV, 1250A, 31.5kA/3sec, 50Hz, 170kVp BIL, single
vertical break, post type, disconnectors without earth switch.
2.2A3
Ten (10) sets of 33kV, 1250A, 31.5kA/3sec, 50Hz, 170kVp BIL, single
vertical break, post type, disconnectors with earth switch.
2.2A4
One (1) sets of 33kV, 2500A, 31.5kA/3sec, 50Hz, 170kVp BIL, single vertical
Schedule A: Requirements
SA-25
Section 1
Requirements
break, post type, disconnectors.
2.2A5
One (1) sets of 36kV, 200A rated outdoor fuse disconnecting switch for station auxiliary
transformer feeder (three phase, 3pole gang manual operated, 10A power fuse, structure
mounted) as shown on the relevant bid drawings.
2.2A6
Thirty(30) nos. of single-phase, 3-core, multi ratio, 36kV, 31.5kA/3sec, 50Hz,
170kVp BIL, post type current transformer.
2.2A7
Thirty six (36) nos. of single-phase, 2-core, 36kV, 31.5kA/3sec, 50Hz,
170kVp BIL, voltage transformers.
2.2A8
Thirty (30) nos. of 30kV rated voltage, 10kA nominal discharge current,
50Hz, Heavy duty station class, single phase surge arresters.
2.2A9
One (1) lot of flexible conductors for busbar, jack bus, jumper, equipment
connections[ACSR conductor], including all necessary clamps & connectors
required for completing 33kV busbar and switchgear connection.
2.2A10
One (1) lot of insulators and fittings including all necessary accessories
required to complete 33kV switchyard.
2.2A11
One (1) lot of steel structures for gantry and equipment supports including
nuts & bolts and cable tray including all necessary fitting & fixing accessories
required for completing 33kV switchyard.
2.2B
Auxiliary Transformers
2.2B1
One (1) sets 33/0.415kV, 200kVA three phase outdoor type station auxiliary
transformers with associated support steel structures including all necessary
connections, insulators & fittings.
2.2C
Control, Protection & Metering 33 kV Circuits
The equipment to be supplied, installed and commissioned shall be as shown
in bid drawings and comprise of:-
2.2C1
Control, Protection & Metering for ten(10) outgoing line circuits.
2.2C2
Tariff metering panel to accommodate programmable & recordable digital 3phase, 4-wire import and export MWh and MVArh meters (accuracy class
0.2) for ten line feeder circuits. For each feeder minimum two meters (main &
check).
Multicore Cables
2.2D
2.2D1
One (1) lot complete set of multicore low voltage 0.6/1.1kV, XLPE insulated
power and control cables (IEC 60502) shall be supplied, installed, glanded,
Schedule A: Requirements
SA-26
Section 1
Requirements
terminated and have individual cores identified to be used for connection of
all equipment supplied under this Contract. The overall switching station
cable routing and core schedules shall also be provided.
2.2E
Earthing and Lightning Protection
2.2E1
One(1) lot of design, supply and installation of earthing system and lightning
protection screen including connections, connectors and clamps, to suit the
substation overall arrangement and provide supporting design calculations for
33kV switching station.
2.2F
Batteries, Chargers and DC Distribution
2.2F1
110V substation NiCad batteries complete with chargers and distribution
switchboard to be supplied, installed and commissioned to provide all DC
supplies to equipment being supplied.
The system shall generally be as shown in bid drawing and shall include:
(d) Two (2) sets of 100% batteries complete, each capacity shall not be less than
150Ah at the 5-hour rate of discharge.
(e) Two (2) sets of battery chargers complete, each charger shall not be less than
50A rating.
(f) One (1) set of DC distribution board. The DC distribution board shall be with
50% spare MCBs for future use.
2.2G
LVAC Distribution
2.2G1
One (1) lot of LVAC switchboard for switching station services to be
supplied, installed and commissioned, to provide the 415/240V supplies to all
equipment being supplied under this bid.
2.2G2
One (1) lot of Tariff metering to accommodate programmable & recordable
digital 3-phase, 4-wire import and export MWh and MVArh meters (accuracy
class 0.2) for one 33/0.415 kV station auxiliary transformer feeder circuits.
For each feeder minimum two meters (main & check).
2.2H
Civil Works, Building and Foundation
2.2H1
Complete earth filling by imported earth free from foreign solid particles and
organic materials in addition to the earth recovered from digging of
foundation, to make the top of the final ground level of substation 3.0m high
from highest flood level and final compaction to be achieved 95% for total
volume 5000 cubic meter. The quantity of earth filling has been specified in
the price schedule, which may vary and will be finalized during detail
engineering. The payment shall be made as per actual measurement of work
Schedule A: Requirements
SA-27
Section 1
Requirements
done.
2.2H2
One (1) lot of complete design, supply and construction of all civil items
required for the outdoor works suitable for switchyard gantry & equipment
foundations, entrance & internal roads, cable trenches, septic tank, soak way,
surfacing, gravel laying, drainage, security fences, retaining wall etc. The
quantity of retaining wall has been specified in the price schedule, which may
vary and will be finalized during detail engineering. The payment shall be
made as per actual measurement of work done.
2.2H3
One (1) lot of complete design, supply and construction of all civil items and
facilities required for the two storied control building.
2.2I
Lighting, Small Power, Air Conditioning and Ventilation
2.2I1
One (1) lot of complete design, supply, installation and commissioning of
equipment to provide lighting, LV power supply, air conditioning system,
ventilation system and emergency DC lighting for the control building.
2.2I2
One (1) lot of complete set of design, supply, installation and commissioning
of equipment to provide lighting (flood light LED type) for security, roadway,
switchyard and emergency DC lighting at strategic locations of 33kV
switching station for equipment operation and inspection.
2.2J
Mandatory Spares, Erection & Test Equipment
Supply of complete spares and spare parts of switchgear, control equipment,
protection relays, meters, erection & test equipment as per quantity mentioned
in schedules of rates and prices. Printed catalogue, operation and service
manual are to be provided for supplied test equipment. The materials shall
have to be handed over to the designated store as per instruction of the
Employer’s Engineer.
Schedule A: Requirements
SA-28
Section 1
Requirements
SCOPE-3(PART-A):Narail 132/33kV AIS Substation:
The equipment to be designed, supplied, installed, tested & commissioned as per detail technical
specification and as shown in bid drawings (volume 2 of 2 of this bid document):
Item
Description
3.1A
132 kV Air Insulated Switchgear (AIS)
The 145kV AIS shall comply with the particular requirements as detailed in the Schedule
of Technical Requirements included as Appendix A3 to this section and shall comprise the
following:-
3.1A.1
Two(2) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL, live tank type, gang
operated, SF6 gas circuit breaker with spring-stored energy operating mechanism (for
Transformer bays).
3.1A.2
Two(2) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL, live tank type, single pole
operated, SF6 gas circuit breaker with spring-stored energy operating mechanism (for
Transsmission line bays).
3.1A.3
Two(2) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL,double side break, post type,
motor operated disconnectors with manual earthing switch.
3.1A.4
Four(4) sets of 132kV, 1250A, 40kA/3sec, 50Hz, 650kVp BIL, double side break, post
type, motor operated disconnectors without earthing switch.
3.1A.5
One(1) set of 132kV, 2000A, 40kA/3sec, 50Hz, 650kVp BIL, double side break, Gantry
mounted post type, motor operated disconnectors without earthing switch.
3.1A.6
Six (6) nos. of single-phase, 4-core, multi ratio, 132kV, 40kA/3sec, 50Hz, 650kVp BIL, post
type current transformer(for line bays).
3.1A.7
Six(6) nos. of single-phase, 4-core, multi ratio, 132kV, 40kA/3sec, 50Hz, 650kVp BIL, post
type current transformer(for Transformer bays).
3.1A.8
Twelve (12) nos. of single-phase, 2-core, 132kV, 40kA/3sec, 50Hz, 650kVp BIL, Inductive
voltage transformers (IVT).
3.1A.9
Twelve(12) nos. of 120kV rated voltage, 102kV(rms) continuous operating voltage at
500c, 10kA nominal discharge current, 50Hz, Heavy duty station class, gapless metal
oxide type, single phase surge arresters.
3.1A.10
Twelve (12) nos. single phase 145kV post type support insulators required for completing
145kV busbar and switchgear connections.
3.1A.11
One(1) lot of flexible conductors for busbar [ACSR] & jackbus, jumper, equipment
connections [ACSR, Single Grosbeak (636 MCM)], including all necessary clamps &
connectors required for completing 132kV busbar and switchgear connection.
Schedule A: Requirements
SA-29
Section 1
Requirements
3.1A.12
One (1) lot of disc insulators and fittings including all necessary accessories required to
complete 132kV switchyard
3.1A.13
One(1) lot of steel structures for gantry and equipment supports including nuts & bolts and
cable tray including all necessary fitting & fixing accessories required to complete 132kV
switchyard.
3.1B
33kV Air Insulated Switches and Connectionfor Auxiliary Transformers
The 33kV AIS shall comply with the particular requirements as detailed in the Schedule of
Technical Requirements included as Appendix A3 to this section andshall comprise the
following:-
3.1B1
Two (2) sets of 33kV, 2500A, 31.5kA/3sec, 50Hz, 170kVp BIL, outdoor Vacuum Circuit
Breakers(VCB) with spring-stored energy operating mechanism.
3.1B2
Four (4) sets of 33kV, 2500A, 31.5kA/3sec, 50Hz, 170kVp BIL, single vertical break, post
type, disconnectors.
3.1B3
Six(6) nos. of single-phase, 3-core, multi ratio, 33kV, 31.5kA/3sec, 50Hz, 170kVp BIL, post
type current transformer.
3.1B4
Six(6) nos. of single-phase, 2-core, 33kV, 31.5kA/3sec, 50Hz, 170kVp BIL, voltage
transformers.
3.1B5
Six(6) nos. of 30kV rated voltage, 10kA nominal discharge current, 50Hz, Heavy duty
station class, single phase surge arresters.
3.1B6
One (1) lot of flexible conductors for jack bus, jumper, equipment connections [ACSR
Conductor], including all necessary clamps & connectors required for connection of 33kV
side of 132/33kV transformer with 33kV bus bar and switchgear connection.
3.1B7
One (1) lot of insulators and fittings including all necessary accessories required to
complete 33kV connection of 33kV incomer side of 132/33kV transformer with 33kV bus.
3.1B8
One (1) lot of steel structures for equipment supports including nuts & bolts and cable tray
including all necessary fitting & fixing accessories required for completing 33kV incomer
side of 132/33kV transformer with 33kV bus.
3.1B9
One (1) sets of 33kV, 200A rated outdoor fuse disconnecting switch for station auxiliary
transformer feeder (three phase, 3pole gang manual operated, 10A power fuse, structure
mounted) as shown on the relevant bid drawings.
3.1C
3.1C1
Power Transformers& Earthing/Auxiliary Transformers
Two (2) sets of 132/33kV, 50/75 MVA (ONAN/ONAF), three phase outdoor type power
transformers with associated bushing CTs including all necessary connections, insulators
& fittings.
Schedule A: Requirements
SA-30
Section 1
Requirements
3.1C2
One(1) sets 33/0.415kV, 200kVA three phase outdoor type station auxiliary transformers
with associated steel support structures including all necessary connections, insulators &
fittings.
3.1D
Control, Protection& Metering
132 kV Circuits
The equipment to be designed, supplied, installed and commissioned is shown in bid
drawings are comprising of :-
3.1D1
Control, Protection & Metering for two (2) sets of overhead line circuits to Keraniganj-1 &
2.
3.1D2
Control, Protection& Metering for two(2) sets of 132/33 kV power transformer circuits
including transformer tap changer control.
3.1D4
Tariff metering panel to accommodate programmable & recordable digital 3-phase, 4-wire
import and export MWh and MVArhmeters (accuracy class 0.2) for two (2) 132 kV line and
two(2) transformer feeder. For each feeder minimum two meters (main & check).
33 kV Circuits
The equipment to be supplied, installed and commissioned is shown in bid drawings are
comprising of:-
3.1D5
Control, Protection& Metering for two sets of power transformer incommer circuits.
3.1D6
Tariff metering panel to accommodate programmable & recordable digital 3-phase, 4-wire
import and export MWh and MVArhmeters (accuracy class 0.2) for two transformer feeder
circuits (Power X-former-I & II). For each feeder minimum two meters (main & check).
3.1E
3.1E1
Multicore Cables
One (1) lot complete set of multicore low voltage 0.6/1.1kV, XLPE insulated power and
control cables (IEC 60502) shall be supplied, installed, glanded, terminated and have
individual cores identified to be used for connection of all equipment supplied under the
Contract. The overall substation cable routing and core schedules shall also be provided.
3.1F
Earthing and Lightning Protection
3.1F1
One(1) lot of design, supply and installation of earthing system and lightning protection
screen including connections, connectors and clamps, to suit the substation overall
arrangement and provide supporting design calculations.
3.1F2
One(1) set of 3-phase portable (maintenance) earthing equipment devices with connectors
and telescopic glass fibre operating pole suitable for plant supplied.
3.1G
Batteries, Chargers and DC Distribution
3.1G1
110V substation NiCad batteries complete with chargers and distribution switchboard
to be supplied, installed and commissioned to provide all DC supplies to equipment
Schedule A: Requirements
SA-31
Section 1
Requirements
being supplied.
The system shall generally be as shown in bid drawing and shall include:
i)
Two (2) sets of 100% batteries complete, each capacity shall not be less than 150Ah
at the 5-hour rate of discharge.
ii)
Two (2) sets of battery chargers complete, each charger shall not be less than 50A
rating.
iii) One (1) set of DC distribution board. The DC distribution board shall be with 50%
overall spare MCB’s for future use.
iv) Two (2) sets of DC/DC Converter 110/48V, 1kVA for communication panels.
v)
3.1H
3.1H1
3.1H2
One (1) set 48V DC distribution board. The DC distribution board shall be with 50%
spare MCBs for future use.
LVAC Distribution
One(1) lot of LVAC switchboard for substation services to be supplied, installed and
commissioned, to provide the 415/240V supplies to all equipment being supplied under
this turnkey Bid.
One(1) lot of Tariff metering to accommodate programmable & recordable digital 3-phase,
4-wire import and export MWh and MVArhmeters (accuracy class 0.2) for one 33/0.415 kV
station auxiliary transformer feeder circuits. For each feeder minimum two meters (main &
check).
3.1H3
One (1) nos. 125A outdoor weatherproof 3-phase with neutral and earth switched socket
outlet and plug as per IEC 309; to be installed, cabled and connected adjacent to the
132/33kV Power Transformer.
3.1I
Civil Works, Building and Foundation
3.1I1
Complete earth filling by imported carried earth free from foreign solid particles and
organic materials in addition to the earth recovered from digging of foundation, to make
the top of the final ground level of substation 0.5m high from highest flood level and final
compaction to be achieved 95% for total volume 60,800 cubic meter. The volume of earth
filling may be varied but the payment shall be as per actual measurement of work done.
3.1I2
One(1) lot of complete design, supply and construction of all civil items required for the
outdoor works suitable for switchyard gantry & equipment foundations, transformer
foundations, blast walls, oil pit, entrance & internal roads, cable trenches, septic tank, soak
way, surfacing, gravel laying, drainage, security fences, boundary wall, sentry post, guard
house, car port, etc.
3.1I3
One(1) lot of complete design, supply and construction of all civil items and facilities
required for the two storied main control building including cable basement.
3.1J
3.1J1
Lighting, Small Power, Air Conditioning and Ventilation
One(1) lot of complete design, supply, installation and commissioning of equipment to
Schedule A: Requirements
SA-32
Section 1
Requirements
provide lighting, LV power supply, air conditioning system, ventilation system and
emergency DC lighting for the main control building.
3.1J2
One(1) lot of complete set of design, supply, installation and commissioning of equipment
to provide lighting (flood light LED type) for security, roadway, switchyard and emergency
DC lighting at strategic locations for equipment operation and inspection.
3.1K
Deleted
3.1L
3.1L1
Fibre Optic Multiplexer Equipment for Communication and Protection
The equipment to be supplied, installed and commissioned shall be as shown on bid
drawing. One(1) lot complete set of design, supply, installation and commissioning of fibre
optic multiplexer equipment including necessary works to interface with existing system is
to be provided for:
- 87 or 21 relay for each transmission line protection (through fibre cores)
- 21 relay carrier signal (main and back-up)
- SCADA data from switchgear and control system
- hot-line telephone system
3.1L2
Underground optical fibre cables (24cores for 132kV switchyard) from terminal box gantry
structure at each 132kV double circuit transmission line termination point to MDF (Main
distribution Frame) to be installed in control room. The Contract includes supply and
installation of MDF and pigtail cables with adequate length.
3.1M
3.1M1
SCADA system for Telecontrol and Telemetering
Complete design, supply, delivery, installation, testing & commissioning of hardwareand
software to provide thetelecontrol & telemetering facilities of complete new132/33kV
substation for integration with the existing National Load DespatchCenter(NLDC) at
Aftabnagarand back up NLDC at Biddut Bhaban. All required electrical signals shall be
transmitted to the NLDC at Aftabnagarand back up NLDC at Biddut Bhaban through the
Remote terminal units (RTU). All HV breakers, motorizeddisconnectors etc. shall be
controlled form NLDC through the remote terminal units(RTU) using IEC 60870-5-104
protocol. New RTU supplied under this contract shall becompetible with existing system(
The existing RTUs are AREVA, France madeMiCOM C264 type). All necessary
modification works in the software of master stationof NLDC and back up station at Biddut
Bhabanare to be carried out.
3.1N
Mandatory Spares, Erection & Test Equipment
Supply of complete spares and spare parts of transformer, switchgear, control equipment,
protection relays, meters, erection & test equipment as per quantity mentioned in
Schedule B. Test equipment are to be supplied from Europe, USA or Japan origin. Printed
catalogue, operation and service manual are to be provided. The materials shall have to
be handed over to the designated store as per instruction of the Engineer.
Schedule A: Requirements
SA-33
Section 1
Requirements
SCOPE-2(PART_B): 33kV AIS Switching Station (REB Part):
The equipment to be designed, supplied, installed, tested & commissioned as per detail
technical specification and as shown in bid drawings (volume 1 of 2 of this bid document):
Item
Description
3.2A
33kV Air Insulated Switchgear (AIS) and Connection:
The 33kV AIS shall comply with the particular requirements as detailed in the
Schedule of Technical Requirements included as Appendix A3 to this section
and bid drawings; shall comprise the following:-
3.2A1
Six (6) sets of 33kV, 1250A, 31.5kA/3sec, 50Hz, 170kVp BIL, outdoor
Vacuum Circuit Breakers (VCB) with spring-stored energy operating
mechanism.
3.2A2
Six(6) sets of 33kV, 1250A, 31.5kA/3sec, 50Hz, 170kVp BIL, single vertical
break, post type, disconnectors without earth switch.
3.2A3
Six (6) sets of 33kV, 1250A, 31.5kA/3sec, 50Hz, 170kVp BIL, single vertical
break, post type, disconnectors with earth switch.
3.2A4
One (1) sets of 33kV, 2500A, 31.5kA/3sec, 50Hz, 170kVp BIL, single vertical
break, post type, disconnectors.
3.2A5
One (1) sets of 36kV, 200A rated outdoor fuse disconnecting switch for station auxiliary
transformer feeder (three phase, 3pole gang manual operated, 10A power fuse, structure
mounted) as shown on the relevant bid drawings.
3.2A6
Eighteen(18) nos. of single-phase, 3-core, multi ratio, 36kV, 31.5kA/3sec,
50Hz, 170kVp BIL, post type current transformer.
3.2A7
Twenty four (24) nos. of single-phase, 2-core, 36kV, 31.5kA/3sec, 50Hz,
170kVp BIL, voltage transformers.
3.2A8
Eighteen(18) nos. of 30kV rated voltage, 10kA nominal discharge current,
50Hz, Heavy duty station class, single phase surge arresters.
3.2A9
One (1) lot of flexible conductors for busbar, jack bus, jumper, equipment
connections[ACSR conductor], including all necessary clamps & connectors
required for completing 33kV busbar and switchgear connection.
3.2A10
One (1) lot of insulators and fittings including all necessary accessories
required to complete 33kV switchyard.
3.2A11
One (1) lot of steel structures for gantry and equipment supports including
Schedule A: Requirements
SA-34
Section 1
Requirements
nuts & bolts and cable tray including all necessary fitting & fixing accessories
required for completing 33kV switchyard.
3.2B
Auxiliary Transformers
3.2B1
One (1) sets 33/0.415kV, 200kVA three phase outdoor type station auxiliary
transformers with associated support steel structures including all necessary
connections, insulators & fittings.
3.2C
Control, Protection & Metering 33 kV Circuits
The equipment to be supplied, installed and commissioned shall be as shown
in bid drawings and comprise of:-
3.2C1
Control, Protection & Metering for six(6) outgoing line circuits.
3.2C2
Tariff metering panel to accommodate programmable & recordable digital 3phase, 4-wire import and export MWh and MVArh meters (accuracy class
0.2) for ten line feeder circuits. For each feeder minimum two meters (main &
check).
3.2D
Multicore Cables
3.2D1
One (1) lot complete set of multicore low voltage 0.6/1.1kV, XLPE insulated
power and control cables (IEC 60502) shall be supplied, installed, glanded,
terminated and have individual cores identified to be used for connection of
all equipment supplied under this Contract. The overall switching station
cable routing and core schedules shall also be provided.
3.2E
Earthing and Lightning Protection
3.2E1
One(1) lot of design, supply and installation of earthing system and lightning
protection screen including connections, connectors and clamps, to suit the
substation overall arrangement and provide supporting design calculations for
33kV switching station.
3.2F
Batteries, Chargers and DC Distribution
3.2F1
110V substation NiCad batteries complete with chargers and distribution
switchboard to be supplied, installed and commissioned to provide all DC
supplies to equipment being supplied.
The system shall generally be as shown in bid drawing and shall include:
(g) Two (2) sets of 100% batteries complete, each capacity shall not be less than
150Ah at the 5-hour rate of discharge.
(h) Two (2) sets of battery chargers complete, each charger shall not be less than
50A rating.
Schedule A: Requirements
SA-35
Section 1
Requirements
(i) One (1) set of DC distribution board. The DC distribution board shall be with
50% spare MCBs for future use.
3.2G
LVAC Distribution
3.2G1
One (1) lot of LVAC switchboard for switching station services to be
supplied, installed and commissioned, to provide the 415/240V supplies to all
equipment being supplied under this bid.
3.2G2
One (1) lot of Tariff metering to accommodate programmable & recordable
digital 3-phase, 4-wire import and export MWh and MVArh meters (accuracy
class 0.2) for one 33/0.415 kV station auxiliary transformer feeder circuits.
For each feeder minimum two meters (main & check).
3.2H
Civil Works, Building and Foundation
3.2H1
Complete earth filling by imported earth free from foreign solid particles and
organic materials in addition to the earth recovered from digging of
foundation, to make the top of the final ground level of substation 3.0m high
from highest flood level and final compaction to be achieved 95% for total
volume 5000 cubic meter. The quantity of earth filling has been specified in
the price schedule, which may vary and will be finalized during detail
engineering. The payment shall be made as per actual measurement of work
done.
3.2H2
One (1) lot of complete design, supply and construction of all civil items
required for the outdoor works suitable for switchyard gantry & equipment
foundations, entrance & internal roads, cable trenches, septic tank, soak way,
surfacing, gravel laying, drainage, security fences, retaining wall etc. The
quantity of retaining wall has been specified in the price schedule, which may
vary and will be finalized during detail engineering. The payment shall be
made as per actual measurement of work done.
3.2H3
One (1) lot of complete design, supply and construction of all civil items and
facilities required for the two storied control building.
3.2I
Lighting, Small Power, Air Conditioning and Ventilation
3.2I1
One (1) lot of complete design, supply, installation and commissioning of
equipment to provide lighting, LV power supply, air conditioning system,
ventilation system and emergency DC lighting for the control building.
3.2I2
One (1) lot of complete set of design, supply, installation and commissioning
of equipment to provide lighting (flood light LED type) for security, roadway,
switchyard and emergency DC lighting at strategic locations of 33kV
switching station for equipment operation and inspection.
Schedule A: Requirements
SA-36
Section 1
3.2J
Requirements
Mandatory Spares, Erection & Test Equipment
Supply of complete spares and spare parts of switchgear, control equipment,
protection relays, meters, erection & test equipment as per quantity mentioned
in schedules of rates and prices. Printed catalogue, operation and service
manual are to be provided for supplied test equipment. The materials shall
have to be handed over to the designated store as per instruction of the
Employer’s Engineer.
Schedule A: Requirements
SA-37
Section 1
Requirements
SCOPE-4 :Extension of existing 132/33kV AIS Substation at Jhenaidaha.
The equipment to be designed, supplied, installed, tested & commissioned as per detail technical
specification and as shown in bid drawings (volume 2 of 2 of this bid document):
Item
Description
4.1A
132 kV Air Insulated Switchgear (AIS)
The 145kV AIS shall comply with the particular requirements as detailed in the Schedule
of Technical Requirements included as Appendix A3 to this section and bid drawings; shall
comprise the following:-
4.1A1
4.1A2
4.1A3
4.1A4
4.1A5
4.1A6
4.1A7
4.1A8
4.1A9
4.1A10
4.1D
4.1D1
4.1D2
4.1E
4.1E1
One(1) sets of 145kV, 1250A, 31.5kA/1sec, 50Hz, 650kVp BIL, live tank type, single pole
operated, SF6 gas circuit breakers with spring-stored energy operating mechanism (for
Transmission line bays).
One(1) sets of 145kV, 1250A, 31.5kA/1sec, 50Hz, 650kVp BIL,single centre break, post
type, motor operated disconnectors with manual earthing switch.
Two(2) sets of 145kV, 1250A, 31.5kA/1sec, 50Hz, 650kVp BIL,single centre break, post
type, motor operated disconnectors without earthing switch.
Three (3) nos. of single-phase, 4-core, multi ratio, 145kV, 31.5kA/1sec, 50Hz, 650kVp BIL,
post type current transformer (for line bays).
Three (3) nos. of single-phase, 2-core, 145kV, 31.5kA/1sec, 50Hz, 650kVp BIL, Inductive
voltage transformers (IVT).
Three nos. of 120kV rated voltage, 102kV(rms) continuous operating voltage at 500c,
10kA nominal discharge current, 50Hz, Heavy duty station class, gapless metal oxide
type, single phase surge arresters.
Two(2) nos. single phase 145kV post type support insulators required for completing
145kV busbar and switchgear connections.
One(1) lot of flexible conductors for jackbus, jumper, equipment connections[ACSR, Single
Grosbeak(636 MCM)], including all necessary clamps & connectors required for extension
to accommodate one line bays.
One (1) lot of insulators and fittings including all necessary accessories required to
complete 145kV switchyard.
One(1) lot of steel structures for gantry and equipment supports including nuts & bolts and
cable tray including all necessary fitting & fixing accessories required to complete 145kV
switchyard.
Control, Protection& Metering
132 kV Circuits
The equipment to be designed, supplied, installed and commissioned is shown in bid
drawings are comprising of :Control, Protection & Metering for one(1) sets of overhead line circuits for one new line
bays.
Tariff metering to accommodate programmable & recordable digital 3-phase, 4-wire import
and export MWh and MVArhmeters (accuracy class 0.2) for one(1) 132kV line. For each
feeder minimum two meters (main & check).
Multicore Cables
One (1) lot complete set of multicore low voltage 0.6/1.1kV, XLPE insulated power and
Schedule A: Requirements
SA-38
Section 1
Requirements
control cables (IEC 60502) shall be supplied, installed, glanded, terminated and have
individual cores identified to be used for connection of all equipment supplied under the
Contract. The cable routing and core schedules shall also be provided.
4.1F
4.1F1
4.1G
4.1G1
4.1H
4.1H1
Earthing and Lightning Protection
One(1) lot of earthing system connection and lightning protection screen including
connections, connectors and clamps for the portion to be extended under this turnkey bid
and to suit the substation overall arrangement.
DC Distribution
One(1) lot of modification of existing DCDB system by necessary MCBs, cable,
connectors etc. required for the plant being installed.
LVAC Distribution
One(1) lot of modification of existing LVAC switchboard for substation services including
supply of all necessary MCBs, bus material, connection cables, lugs etc. to provide the
415/240V supplies to all equipment being supplied under this turnkey Bid.
4.1I
4.1I1
Civil Works, Building and Foundation
One(1) lot of complete design, supply and construction of all civil items required for the
outdoor works suitable for switchyard gantry & equipment foundations, internal roads,
cable trenches, surfacing, gravel laying, drainage, etc.
4.1I2
One(1) lot ofmodification works and construction of all civil items and facilities required for
the main control building including floor cutting & finishing works to accommodate new line
bays.
4.1J
Fibre Optic Multiplexer Equipment for Communication and Protection
4.1J1
The equipment to be supplied, installed and commissioned shall be as shown on bid
drawing. One(1) lot complete set of design, supply, installation and commissioning for
extension of existing fibre optic multiplexer & communication equipment(AREVA, France
made MSE 5001 type) and necessary works to interface with existing system is to be
provided to accommodate new bay.
4.1K
4.1K1
SCADA system for Telecontrol and Telemetering
One(1) lot of Complete design, supply, delivery, installation, testing & commissioning of
hardware and software to provide the telecontrol & telemetering facilities required at the
existing National Load Despatch Center (NLDC) at Rampura for integration of one new
132kV line bays. All required electrical signals shall be transmitted to the NLDC through
the Remote terminal units (RTU). All HV breakers, motorized disconnectors etc. shall be
controlled form NLDC through the remote terminal units (RTU) using IEC 60870-5-104
protocol. All necessary modification works in the software of master station of NLDC are to
be carried out. The existing RTUs are AREVA, France made MiCOM C264 type.
Schedule A: Requirements
SA-39
Section 1
Requirements
SCOPE-5 :Extension of existing 132/33kV AIS Substation at Magura.
The equipment to be designed, supplied, installed, tested & commissioned as per detail technical
specification and as shown in bid drawings (volume 2 of 2 of this bid document):
Item
Description
5.1A
132 kV Air Insulated Switchgear (AIS)
The 145kV AIS shall comply with the particular requirements as detailed in the Schedule
of Technical Requirements included as Appendix A3 to this section and bid drawings; shall
comprise the following:-
5.1A1
5.1A2
5.1A3
5.1A4
5.1A5
5.1A6
5.1A7
5.1A8
5.1A9
5.1A10
5.1D
5.1D1
5.1D2
5.1E
5.1E1
Three(1) sets of 145kV, 1250A, 31.5kA/1sec, 50Hz, 650kVp BIL, live tank type, single pole
operated, SF6 gas circuit breakers with spring-stored energy operating mechanism (for
Transmission line bays).
Three(3) sets of 145kV, 1250A, 31.5kA/1sec, 50Hz, 650kVp BIL,single centre break, post
type, motor operated disconnectors with manual earthing switch.
Nine(9) sets of 145kV, 1250A, 31.5kA/1sec, 50Hz, 650kVp BIL,single centre break, post
type, motor operated disconnectors without earthing switch.
Nine (9) nos. of single-phase, 4-core, multi ratio, 145kV, 31.5kA/1sec, 50Hz, 650kVp BIL,
post type current transformer (for line bays).
Nine(9) nos. of single-phase, 2-core, 145kV, 31.5kA/1sec, 50Hz, 650kVp BIL, Inductive
voltage transformers (IVT).
Nine(9) nos. of 120kV rated voltage, 102kV(rms) continuous operating voltage at 500c,
10kA nominal discharge current, 50Hz, Heavy duty station class, gapless metal oxide
type, single phase surge arresters.
Deleted
One(1) lot of flexible conductors for jackbus, jumper, equipment connections[ACSR, Single
Grosbeak(636 MCM)], including all necessary clamps & connectors required for extension
to accommodate three line bays.
One (1) lot of insulators and fittings including all necessary accessories required to
complete 145kV switchyard.
One(1) lot of steel structures for gantry and equipment supports including nuts & bolts and
cable tray including all necessary fitting & fixing accessories required to complete 145kV
switchyard.
Control, Protection& Metering
132 kV Circuits
The equipment to be designed, supplied, installed and commissioned is shown in bid
drawings are comprising of :Control, Protection & Metering for three(3) sets of overhead line circuits for one new line
bays.
Tariff metering to accommodate programmable & recordable digital 3-phase, 4-wire import
and export MWh and MVArhmeters (accuracy class 0.2) for three(3) 132kV line. For each
feeder minimum two meters (main & check).
Multicore Cables
One (1) lot complete set of multicore low voltage 0.6/1.1kV, XLPE insulated power and
control cables (IEC 60502) shall be supplied, installed, glanded, terminated and have
Schedule A: Requirements
SA-40
Section 1
Requirements
individual cores identified to be used for connection of all equipment supplied under the
Contract. The cable routing and core schedules shall also be provided.
5.1F
5.1F1
5.1G
5.1G1
5.1H
5.1H1
Earthing and Lightning Protection
One(1) lot of earthing system connection and lightning protection screen including
connections, connectors and clamps for the portion to be extended under this turnkey bid
and to suit the substation overall arrangement.
DC Distribution
One(1) lot of modification of existing DCDB system by necessary MCBs, cable,
connectors etc. required for the plant being installed.
LVAC Distribution
One(1) lot of modification of existing LVAC switchboard for substation services including
supply of all necessary MCBs, bus material, connection cables, lugs etc. to provide the
415/240V supplies to all equipment being supplied under this turnkey Bid.
5.1I
5.1I1
Civil Works, Building and Foundation
One(1) lot of complete design, supply and construction of all civil items required for the
outdoor works suitable for switchyard gantry & equipment foundations, internal roads,
cable trenches, surfacing, gravel laying, drainage, etc.
5.1I2
One(1) lot ofmodification works and construction of all civil items and facilities required for
the main control building including floor cutting & finishing works to accommodate new line
bays.
5.1J
Fibre Optic Multiplexer Equipment for Communication and Protection
5.1J1
The equipment to be supplied, installed and commissioned shall be as shown on bid
drawing. One(1) lot complete set of design, supply, installation and commissioning for
extension of existing fibre optic multiplexer & communication equipment(AREVA, France
made MSE 5001 type) and necessary works to interface with existing system is to be
provided to accommodate new bay.
5.1J2
Underground optical fibre cables (24cores for 132kV switchyard) from terminal box gantry
structure at each 132kV double circuit transmission line termination point to MDF (Main
distribution Frame) to be installed in control room. The Contract includes supply and
installation of MDF and pigtail cables with adequate length.
5.1K
5.1K1
SCADA system for Telecontrol and Telemetering
One(1) lot of Complete design, supply, delivery, installation, testing & commissioning of
hardware and software to provide the telecontrol & telemetering facilities required at the
existing National Load Despatch Center (NLDC) at Rampura for integration of three new
132kV line bays. All required electrical signals shall be transmitted to the NLDC through
the Remote terminal units (RTU). All HV breakers, motorized disconnectors etc. shall be
controlled form NLDC through the remote terminal units (RTU) using IEC 60870-5-104
protocol. All necessary modification works in the software of master station of NLDC are to
be carried out. The existing RTUs are AREVA, France made MiCOM C264 type.
Schedule A: Requirements
SA-41
Section 1
Requirements
A3.SCHEDULE OF TECHNICAL REQUIREMENTS
Schedule A: Requirements
SA-42
Section 1
Requirements
APPENDIX- A3.1
SCHEDULE OF TECHNICAL REQUIREMENTS OF
132kV and 33kV AIR INSULATED SWITCHGEAR (AIS)
Sl.
No.
1.
2.
3.
Description
Site Condition
Max. Altitude above sea level
Max.
Ambient
temperature
outdoor
Min.
Ambient
temperature
outdoor
Max. Ambient relative humidity
Max. Seismic acceleration at floor
level
- horizontal
- vertical
Electrical Data
Nominal system Voltage
Rated Voltage
Rated Frequency
Insulation Level
- lightning impulse withstand
- switching impulse withstand
- 50 Hz withstand 1 minute
Rated continuous current at
40oCambient temperature
- main busbar and bus coupler
- transformer bay
- line bay
Rated short time withstand
- current
- duration
Rated peak withstand current
Secondary Circuit
Auxiliary voltage
- for control and signal
- for remote control
- for heating
- tolerances
Schedule A: Requirements
Unit
132kV
33kV
meter not more than 150
ºC
+45
ºC
+4
%
100
g
g
0.1
0.1
kV
kV
Hz
132
145
50
33
36
50
kVp
kVp
kV
650
—
275
170
—
70
A
A
A
2000
1250
1250
kA
Sec
kA
40
3
100
V dc
V dc
110
110
V ac
%
415/240
-15/+15
2500
2500
1250
25
3
78
SA-43
Section 1
4.
4.1
1
Circuit Breakers
145kV Class Circuit Breakers
Type
Requirements
Outdoor,
SF6 insulated,
tank type
live
2
Standard
IEC 62271-100
3
Rated voltage
145 kV
4
Rated short-duration power frequency withstand voltage
(1 min.)
- Between line terminal and ground
- Between terminals with CB open
- Between terminals with isolator open
275 kV rms
275 kV rms
315 kV rms
Rated lightning impulse withstand voltage
- Between line terminal and ground
- Between terminals with CB open
- Between terminals with isolator open
650 kV peak
650 kV peak
750 kV peak
6
First pole to clear factor
1.3
7
Rated current
- Bus coupler
- Transformer bay
- Line bay
2000 A
1250 A
1250 A
8
Rated short circuit breaking current
40 kA rms
9
Rated short circuit making current
100 kA peak
10
Short time withstand current for 3 sec.
40 kA rms
11
Max. radio interference voltage for frequency between 500 micro V
0.5MHz and 2MHz in all positions
(at 92 kV rms)
12
Total closing time
Not more than 150 ms
13
Total breaking time
Not more than 100 ms
14
Operating mechanism
Spring
15
Rated duty cycle
O-0.3S-CO-3min-CO
16
Reclosing
Single phase & Three
phase auto-reclosing
17
Creepage distance
25 mm/kV
18
Number of closing coils
1
19
Number of tripping coils
2
5
Schedule A: Requirements
SA-44
Section 1
20
Requirements
Number of auxiliary contacts for:
- Making
- Breaking
- Middle position
Min. 12
Min. 12
0
Protection class
IP55
1
36kV Class Circuit Breakers
Type
Outdoor type VCB
2
Standard
IEC 62271-100
3
Rated voltage
36 kV
4
Rated short-duration power frequency withstand voltage
(1 min.)
70 kV rms
5
Rated lightning impulse withstand voltage
170 kV peak
6
First pole to clear factor
1.5
7
Rated current
For Transformer Incommer and bus section
For outgoing feeder
2500 A
1250 A
8
Rated short circuit breaking current
31.5 kA rms
9
Rated short circuit making current
78kA peak
10
Short time withstand current for 3 sec.
31.5 kA rms
11
Total closing time
Not more than 150 ms
12
Total breaking time
Not more than 100 ms
13
Operating mechanism
Motor spring stored
energy
14
Rated duty cycle
O-0.3S-CO-3min-CO
15
Number of closing coils
1
16
Number of tripping coils
2
17
Number of auxiliary contacts for:
- Making
- Breaking
- Middle position
Min. 8
Min. 8
0
Protection class
IP55
21
4.2
18
5.
5.1
Disconnector Switches/Isolators
1
145kV Class Disconnector and Earthing Switch
Type
2
Standard
Schedule A: Requirements
Outdoor,
i)Double side break
ii)SingleCenter break
ii)Single break Series
IEC 62271-102
SA-45
Section 1
3
4
Requirements
Rated voltage
145 kV
Rated short-duration power frequency withstand voltage (1
min.)
- To earth
275 kV rms
- Across isolating distance
315 kV rms
Rated lightning impulse withstand voltage
- To earth
650 kV peak
- Across isolating distance
750 kV peak
Rated normal current
- Bus coupler
2000 A
- Transformer bay
1250 A
- Line bay
1250 A
Rated short circuit current (Ith), 1s
40 kA rms
Rated short circuit current (Idyn)
100 kA peak
Creepage distance of insulator
25 mm/kV
Operating mechanism of isolator-----AC motor operated
Earthing switch---------------------------manual operated
Number of auxiliary contacts for main switch
- Making
Min. 6
- Breaking
Min. 6
- Middle position
Min. 1
Number of auxiliary contacts for earthing switch
- Making
Min. 6
- Breaking
Min. 6
- Middle position
Min. 1
Radio interference level for 0.5 MHz to 2 MHz
500 micro V
(at 92 kV rms)
5
6
7
8
9
10
11
12
13
5.2
1
36kV Class Isolators
Type
2
3
4
Standard
IEC 62271-102
Rated voltage
36 kV
Rated short-duration power frequency withstand voltage 70 kV rms
(1 min.)
Rated lightning impulse withstand voltage
170 kV peak
Rated normal current
2500 A
1250A
Rated short circuit current (Ith), 1s
31.5 kA rms
Rated short circuit current (Idyn)
78 kA peak
Creepage distance of insulator
25 mm/kV
Operating mechanism of isolator
manual operated
Number of auxiliary contacts for main switch
5
6
7
8
9
10
11
Schedule A: Requirements
Outdoor,
Single vertical break
SA-46
Section 1
Requirements
6.
- Making / Breaking
Instrument Transformers
6.1
Instrument Transformers
Min. 6 / 6
145kV
36kV
650 kVp
170 kVp
1
Rated lightning impulse withstand
voltage
2
Rated switching impulse withstand
voltage
3
Power frequency withstand
voltage (1 min.)
4
Corona extinction voltage
5
Radio interference level for 0.5
MHz to 2 MHz
1000 micro V
(at 92 kVrms)
1000 micro V
(at 92 kVrms)
6
Partial discharge level
10 pC
10 pC
7
Type of insulation
Class A
Class A
275kVrms
70 kVrms
-
6.2.1 145kV Class Current Transformers(for transformer bay)
1 No. of Cores
Total-4
(Metering-1 plus Protection-3)
2
Ratio
800-400/1/1/1/1A
3
Class of accuracy
4
Burden(VA)
5
Min. knee point voltage at lowest ratio(Volts)
6
Max. magnetizingcurrent guaranteed at
knee point voltage & the lowest ratio(mA)
M.R.
7
Max. resistance of secondary winding at
75 0C and at lowest ratio(ohms)
M.R.
- Protection : 5P20/Cl.X
- Metering : Class 0.2
30
>[email protected] max ratio for protection core
<[email protected] max ratio for metering core
6.2.2 36kV Class Current Transformers (for transformer bay)
1
No. of Cores
2
Ratio
2400-1600/5/5/5[for TR]
800-400/5/5/5[for outgoing feeder]
3
Class of accuracy
- Protection : 5P20
- Metering : Class 0.2
4
Burden(VA)
5
Min. knee point voltage at lowest ratio(Volts)
Schedule A: Requirements
3
30
>[email protected] max ratio for protection core
SA-47
Section 1
Requirements
<[email protected] max ratio for metering core
6
Max. magnetizingcurrent guaranteed at
knee point voltage & the lowest ratio(mA)
M.R
7
Max. resistance of secondary winding at
75 0C and at lowest ratio (ohms)
M.R
6.3
145kV Class Current Transformers(for line bay)
1 No. of Cores
Total-4
(Metering-1 plus Protection-3)
2
Ratio
3
Class of accuracy
4
Burden(VA)
5
Min. knee point voltage at lowest ratio(Volts)
6
Max. magnetizingcurrent guaranteed at
knee point voltage & the lowest ratio(mA)
M.R
7
Max. resistance of secondary winding at
75 0C and at lowest ratio (ohms)
M.R
6.4
1
1600-800/1/1/1/1
- Protection : 5P20/Cl.X
- Metering : Class 0.2
30
>[email protected] max ratio for protection core
<[email protected] max ratio for metering core
145kV Class Current Transformers(for bus coupler bay)
Core No.
I
2
Ratio
3
II
2000/1
2000/1
Purpose
Protection
Measuring
4
Class of accuracy
5P20/Cl.X
0.2
5
Burden(VA)
30
30
6
Min. knee point voltage
at lowest ratio(Volts)
>[email protected] max ratio for
protection core
<[email protected] max ratio for
metering core
7
Max. magnetising
current guaranteed at
knee point voltage & the
lowest ratio(mA)
M.R
M.R
8
Max. resistance of
secondary winding at
75 0C and at lowest ratio
(ohms)
M.R
M.R
6.5
1
2
145kV Class Voltage Transformer
Rated voltage levels
High frequency capacitance for
entire carrier frequency range
Schedule A: Requirements
145 kV
Within 80% to 150% of
ratedcapacitance
SA-48
Section 1
3
Rated Voltage Factor
1.2 continuous;1.5 for 30 seconds
4
Rated total capacitance(pF)
6600, +10% and -5%
5
Phase angle error (minutes)
20
6
Acceptable limit of variation of total
capacitance over the entire carrier
frequency range
+ 50% and -20% of the rated
capacitance
7
Equivalent series resistance over the
entire carrier frequency range or
temperature range (ohms)
Less than 40
8
Stray capacitance and stray
conductance of low voltage terminal
over the entire capacitance.
As per IEC
9
Core details
Core-I :
Core-II
10
Purpose
Protection
Metering
11
Secondary Voltage
110/√3
110/√3
12
Burden (VA)
100
50
13
Class of accuracy
3P
0.2
14
Rated total thermal burden(VA)
50
50
15
One minute power frequency
withstand voltage between LV
terminal and earth(kV rms)
16
6.6
1
Withstand voltage for secondary
winding (kV rms)
36kV Class Voltage Transformer
Rated voltage levels
4(10 if the low voltageterminal is exposed)
2
36 kV
2
Rated Voltage Factor
1.2 continuous;1.5 for 30 seconds
3
Phase angle error (minutes)
20
4
Core details
Core-I :
5
Purpose
Protection Metering
6
Secondary Voltage
110/√3
110/√3
7
Burden (VA)
50
25
8
Class of accuracy
3P
0.2
9
One minute power frequency
withstand voltage between LV
terminal and earth(kV rms)
10
7
Requirements
Withstand voltage for secondary
winding (kV rms)
Core-II :
4(10 if the low voltageterminal is exposed)
2
Surge Arresters
Schedule A: Requirements
SA-49
Section 1
Requirements
1
Max. highest system voltage
2
Type
3
Standard
4
Rated voltage
5
Max. continuous operating
voltage
102kVrms
6
Nominal discharge current
10kA
10kA
7
Discharge class
Heavy
duty 3
Heavy
duty 3
8
Surge counter
Yes
Yes
9
Leakage current detector
Yes
Yes
Schedule A: Requirements
145kV
36kV
Outdoor type, ZnO, Gapless
IEC 60099-4
120kV
30kV
SA-50
APPENDIX- A3.2A
SCHEDULE OF TECHNICAL REQUIREMENTS OF
132/33 kV POWER TRANSFORMER (50/75MVA)
Sl. No.
Description
RATING AND PERFORMANCE
1
Maximum continuous rating (MCR)
MVA
2
Number of Phases
3
Number of windings
4
Normal ratio of transformation at no load and
kV
at principle tap - HV/LV
5.1
Corresponding highest system voltages
kV
5.2
Corresponding lowest system frequency
Hz
6
Minimum withstand voltages:
- Full wave impulse withstand
of windings
kVp
of line terminal bushings
kVp
- Induced over voltage
kVrms
- Power frequency withstand of neutral
kV rms
7
Type of cooling
8
Minimum continuous rating
MVA
9
Rating of tertiary windings
MVA
10
Service conditions:
- External cooling medium
- Altitude not exceeding
m
0
- Air temperature not exceeding
C
Average air temperature in any
one year not exceeding:
0
- In any one day
C
0
- Average in one year
C
11.1
11.2
11.3
12
Maximum temperature :
- Top oil rise normal
- Average ONAN winding rise
- Average ONAF winding rise
Maximum hot spot temperature at
maximum continuous rating at
yearly average ambient temperature
Winding hot spot temperature on
emergency overload not exceeding
Phase connections:
- HV winding
- LV winding
- TV winding
Schedule A: Requirements
0
75
3
2
132/33
145/36
48
650/170
650/170
275/70
38
ONAN/ONAF
50/75
NA
Air
150
45
45
35
C
C
0
C
50
55
55
0
C
98
0
C
140
0
Delta
Star
-
SA-51
13
14
15
16.1
16.2
17
18
19
20
21
22
- Vector group - HV/LV/TV
Short circuit withstand fault level (one sec.)at
terminals of:
- 132 kV busbars
- 33 kV busbars
Impedance voltage at 75ºC and MCR (75 MVA)
between windings (% on HV Base)
at Nominal tap
at maximum tap
at minimum tap
Not used
Total range of variation of on load
transformation ratio (on HV side) as sl. no. 4:
- Ratio
- Size of steps
Type of control
Line drop compensation
Whether automatic control required and
referenced voltage
Whether separate remote control panel required
DC supply:
- Nominal
- Maximum float voltage
Whether provision for supervisory control
required, including AVR setting
Whether marshalling kiosk required
23
Number of transformers for which automatic
control is to be suitable
24
TERMINATIONS
Bushing insulators or cable boxes
on line and neutral terminals:
i) HV line
ii) Neutral
iii) LV line
25
BCT PARTICULARS
i) HV (132kV) Side
Core 1
Schedule A: Requirements
Dyn1
kA
kA
40
31.5
%
%
%
12 ~14
12 ~14
12 ~14
%
%
±10
1.25
On load local,
remote and
supervisory
electrical and
hand
operation
Yes
Yes, 110V,
50Hz
Yes
V
V
110
125
Yes
Tank side
Cubicle
2 (and
provision for
future 3rd)
Oil/Air
Bushings
Oil/Air
Bushings
Oil/Air
Bushing
400/1,
Cl-5P20,
30VA
SA-52
Core 2
Ratio, burden
and accuracy
class shall be
matched with
WTI meter
1600/1,
Cl-5P20,
30VA
for WTI meter
for
Tapchanger
1600/1,
Cl-5P20,
30VA
25 mm/kV
of system rated
(highest)
voltage
ii) LV (33 kV) Side Core 1
Core 2
Core 3
iii) Neutral Bushing (core 1 & 2):
26
Pollution category of bushing insulators
27
COOLING
i) Number of cooler banks required per
transformer
ii) Rating of each cooler bank as percentage of
total loss at CMR
iii) Standby cooling requirement
28
29
GENERAL
Type of oil preservation system
Maximum acceptable noise level
Schedule A: Requirements
%
i)To suit
transformer
design
ii)100%
iii)One fan in
each group
Air Cell
78 dBA
SA-53
APPENDIX- A3.2B
SCHEDULE OF TECHNICAL REQUIREMENTS OF
33/0.415 kV AUXILIARY (STATION SERVICE) TRANSFORMER
SL. No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Description
AUXILIARY TRANSFORMER
Nominal rating
kVA
200
Number of phase
3
Frequency
Hz
50
No-load voltage ratio
kV
33/0.415
Corresponding highest system voltage
kV
36/1.1
Type of cooling
ONAN
Coolant
Mineral Oil
Type
Core, Conservator Type
Installation
Outdoor, Tropical and high rainfall and humidity
Earthing
Neutral solidly earthed in interconnected star winding
Neutral earthed in LT 3 phase, 4 wire system
Windings
Double wound of high conductivity copper
Test voltage
Impulse test voltage (1.2/50 ㎲)
kV 170/10 (HT/LT)
Power frequency withstand voltage kV
70/2.5 (HT/LT)
for 1 min
Vector group
dyn11
Neutral to be brought out
HT: no, LT: Yes
Neutral insulation
Full insulation and 100% loading capacity
LT bushing
4 nos.
Impedance voltage
% 4-5
Tapping range
±5% in the step of 2.5
Tap changer control
Schedule A: Requirements
Off load tap changer
Manual
SA-54
APPENDIX- A3.3
SCHEDULE OF TECHNICAL REQUIREMENTS OF
NI-CAD BATTERY(110V DC System)
SL. No.
Description
1.
Installation
2.
Cell type
3.
Voltage (Normal)
4.
Float voltage
5.
Equalizing voltage
6.
Capacity in AH at 20°C
150 AH @ 5 Hr (for 33kV Control Room)
7.
Ambient temperature
8.
Positive plate
9.
Negative plate
10.
Type of container
11.
Discharge voltage
12.
Sp. gravity of electrolyte
13.
Sp. gravity of electrolyte (Charged)
14.
Vent plug
15.
Cell condition
16.
Battery stand
17.
Standard
SL. No.
: Indoor
: Ni-cd
: 1.2 volts per cell
: 1.40-1.42 volt/cell
: 1.55 - 1.65 volt/cell
: 460 AH @ 5 Hr (for 230/132kV Control Room)
: 45°C
: Tubular
: Pasted
: Plastic polymer
: 1.0 V/Cell
: 1.19 ± 1%
: 1.23 ± .010 at 20°C
: Anti-corrosive & fire proof
: Pre-charged.
: Steel frame of step type
: IEC or equivalent
APPENDIX- A3.4
SCHEDULE OF TECHNICAL REQUIREMENTS OF
110 V BATERY CHARGER
Description
A) GENERAL
1.
2.
3.
4.
Installation
Rectifier type
Rated D.C. voltage
Rated output current
5.
6.
Charging mode
High Voltage Insulation
7.
8.
9.
10.
11.
12.
13.
Insulation resistance
Cooling system
Relative humidity
Ambient temperature
Noise level
Altitude
Applicable Standard
Schedule A: Requirements
: Indoor
: Thyristor controlled.
: 110V ±5%
: 120 Amps(for 230/132kV control room)
: 50 Amps(for 33kV control room)
:Both constant current & constant voltage
: 1000 V AC for 1 minute between
input to output and input to ground
: 10 MW with 500 V DC for 1 minute
: Self & natural air cooled.
: Up to 98%
: 45°C (max.)
: 65 dB (max)
: 150 m
: IEC or equivalent.
SA-55
B) TECHNICAL DATA
A.C. INPUT
1.
Voltage
2.
Phase
3.
Frequency
4.
Input AC voltage variation
5.
Power factor (Full range)
6.
Efficiency (Full load)
7.
Charge Characteristics
(During float charge)
8.
Current limitation
D.C. OUTPUT
1.
Voltage
2.
Ripple Voltage (Full load)
3.
Charge modes (3 level)
4.
Float Voltage (adjustable)
5.
Boost Voltage (adjustable)
Schedule A: Requirements
: 415 Volts
: 3 Phase
: 50 ± 5% Hz
: ± 5%
: 0.8
: 85%
: Constant current /Constant voltage
: 110%
: 110 ± 5% volt
: ± 3%
: Charge, Float charge & Boost charge
: 1.42 volt/cell
: 1.53 volt/cell
SA-56
APPENDIX A3.5
SCHEDULE OF TECHNICAL REQUIREMENTS OF
SUBSTATION AUTOMATION SYSTEM
1. General Requirement:
Standards to be complied with Substation Automation system
Test Ca. Damp heat steady state
IEC 60068-2-3
Test Db and guidance; Damp heat cyclic
IEC 60068-2-30
Digital I/O, Analogue I/O dielectric Tests
IEC 60870-3 class 2
Digital I/O, Surge withstand test
IEC 60801-5/Class 2
Radio interference test
IEC 60870-3/Calss 2
Transient fast burst test
IEC 60801-4/4
Static Discharge
IEC 60801-2/4
Electromagnetic fields
IEC 60801-3-3
Temperature range (min/max)
Relative humidity
Intelligent Electronic Devices (IED’s)
- serial communication interface included?
- Protection & Control IED’s connected same bus?
- self monitoring
- display of measured values
- remote parameterization
- disturbance record upload and analysis
Availability Calculation shall be furnished for each
equipments as well as for the entire system
2. Detailed Requirements:
Number of years of proven field experience of
offered system.
(Note: proof of experience should be furnished. The
components used in the offered system and those
with
field experience should be the same)
Design life of substation Automation System
Manufacturers quality assurance system
Dimensions of cubicle
- Width
- Depth
- Height
- Floor load
3. Station Level Equipment:
Station Controller
MTBF (Mean time between Failures)
MTTR (Mean time to repair)
Schedule A: Requirements
℃
%
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
0/50
93
10Yrs.
20 Yrs
ISO 9001/9002 or equivalent
mm
mm
mm
N/m
2
max.600
Industrial PC
Hrs
Hrs
SA-57
Dual Station Computers Provided in redundant hot
standby
Hot standby take over time
Annunciator for Station PC system software
Number of years of proven field experience of
offered
software
Operating System
All standard picture as per spec included in HMI
Process Status Display & Command Procedures
Event processing as per spec
Alarm processing as per spec
Reports as per spec
Trend Display as per spec
User Authority levels as per spec
System supervision & monitoring as per spec
Automatic sequence control as per spec
4. Gateway to National Load dispatch Center
Number of years of proven filed experience of
offered
unit
Insulation tests
Fast disturbance tests
Industrial environment
Industrial grade hardware with no moving parts
(PC based gateway is not accepted)
Design life of offered equipment
Redundant communication channel
Redundant CPU
Redundant DC/DC Supply
MTBF (Mean time between Failures)
MTTR (Mean time to repair)
5. Station Bus:
Physical Meduim
6. Interbay Bus
Physical Meduim
7. Printer server
MTBF
8. Event Printer
MTBF
9. Hard Copy colour Printer
MTBF
10. Master Clock – GPS (Global Positioning System) Receiver:
Schedule A: Requirements
Yes
Seconds
16 Windows
5 Yrs
Windows
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
5Yrs
IEC 60255-5
IEC 61000-4-4,Calss 4
EN 50081-2 Class A
Yes
20 Yrs
Yes
Yes
Yes
Hrs
Hrs
Glass fibre optic
Glass fibre optic
Hrs
Hrs
Hrs
SA-58
MTBF
11. Bay control Unit - HV
Number of years of proven field experience of
offered
unit
Separate Bay controller unit provided for each bay &
feeder
Type of bay controller offered HV/MV
Select Before Operate with Open Execute & Close
Execute
Single bit dependence
Interlocking, bay & Station wide
Synchrocheck function
- Maximum Voltage difference
- Maximum Frequency difference
- Maximum Phase difference
Double command blocking
Independent settable parameter groups
Local Display Unit
Sequence of event recorder
- Events
- Time resolution
Disturbance recorder function
Comprehensive self-supervision
Battery free backup of events and disturbance
records
Insulation tests
Fast disturbance tests
MTBF
MTTR
Temperature range: IED’s
- Operation
- Transport and storage
Relative humidity:
- Operating max./min
- Transport and storage
12. Back up control mimic -HV
Schedule A: Requirements
Hrs
5 Yrs
Yes
HV
Yes
No
Yes
Specify range
Specify range
Specify range
Yes
4
Yes
256
1 ms
Yes
Yes
Yes
IEC 60255-5
IEC 61000-4-4, Class 4
Hrs
Hrs
℃
-10 to +50
℃
-10 to +50
%
%
93
93
SA-59
Control functionality:
Control of breaker as well as all isolators/earthing
switch
(Control functionality should not be affected if bay
controller fails)
Key-Locked
Interlock override function
Separate backup control mimic provided for each bay
& feeder
13. Bay Control Unit - MV
Number of years of proven field experience of
offered
unit
Separate Bay controller unit provided for each bay &
feeder
Control functionality implementation in software:
Select before Operate with Open Execute & Close
Execute
Interlocking, Bay & Station Wide
Synchrocheck function
- Maximum Voltage difference
- Maximum Frequency difference
- Maximum Phase difference
Local Display Unit
Sequence of event recorder
- Events
- Time resolution
Disturbance recorder function
Comprehensive self-supervision
Insulation tests
Fast disturbance tests
MTBF
MTTR
Temperature range: IED’s
- Operation
- Transport and storage
Relative humidity:
- Operating max./min
- Transport and storage
14. Back up control mimic - MV
Control functionality:
Control of breaker as well as all isolators/earthing
switches
Schedule A: Requirements
Yes
Yes
Yes
Yes
5 Yrs
Yes
Yes
Yes
Specify range
Specify range
Specify range
Yes
Specify
1 ms
Yes
Yes
IEC 60255-5
IEC 61000-4-4, Class 4
Hrs
Hrs
℃
-10 to +50
℃
-10 to +70
%
%
93
93
Yes
Yes
SA-60
Separate backup control mimic provided for each bay
& feeder
15. System Performance:
Exchange of display (First reaction)
Presentation of a binary change in the process
display
Presentation of an analogue change in the process
display
From order to process output
From order to updated of display
Schedule A: Requirements
<1S
< 0.5 S
<1S
< 0.5 S
< 1.5 S
SA-61
APPENDIX A3.6
SCHEDULE OF TECHNICAL REQUIREMENTS OF
FIBRE OPTIC MULTIPLEXER EQUIPMENT
UNIT
SL.NO. DESCRIPTION
1.0
GENERAL:
1.1
1.2
1.3
1.4
1.5
Type of multiplexer
Complying to ITU-T rec.
Transmission Capacity
Access capacity on 64 kbit/s
Access capacity on 2 Mbit/s
1.6
Redundant central processor
1.7
2.0
2.1
3.0
3.1
3.2
Digital cross connect function
Available AGGREGATES:
Optical aggregates (ITU-T G.957)
Available TRUNK INTERFACES:
HDB3, 2 Mbit/s interfaces per module
Complying to ITU-T rec.
3.3
HDSL, 2Mbit/s interface: no of copper
wires
Capacity on 2Mbit/s or on 1Mbit/s
4.0
4.1
4.1.1
4.1.2
4.1.3
Mbit/s
channels
channels
4.1.4
4.2
4.2.1
4.2.2
4.3
4.3.1
4.3.1.1
4.3.1.2
4.3.1.3
Digital, 2Mbit/s CAS or PRI
Voice interfaces for remote subscriber:
2wire, subscriber side
2wire, PABX side
Integrated teleprotection
Interface for Commands:
Number of independent commands
Transmission time max.
Signal voltage
4.3.1.4
1 + 1 com path protection
4.3.2
Interface(s) for Distance Protection:
Schedule A: Requirements
SDH: ADM
Yes
STM-4: 620
Minimum 200
Minimum 40
Shall be available
Fully non-blocking
L-1.1, L-1.2
No.
No.
ch
ch / pair of wire
Capacity selectable
Available USER INTERFACES
Voice interfaces for trunk lines:
1 + 1 com path protection, available for all
Analogue, 4wire with E&M: Input level
Output level
Analogue, 2wire with E&M: Input level
Output level
REQUIRED
Minimum 8
G.703, transparent
G.704, selectable
4 or 2
30 or 15
30 / 2 pairs
30 / 1 pair
15 / 1 pair
yes
dBr
dBr
dBr
dBr
No.
ms
Vpeak
+7.5 .. –16
+7.0 .. –16.5
+6.5 .. –12.5
–1.0 .. -20
yes
-5 .. +4 / -7.5 .. -1
-5 .. +4 / -7.5 .. -3
4
6
250
yes
SA-62
kbit/s
64
kbit/s
Minimum 64
4.3.2.1
Electrical interface: G.703
4.3.2.2
4.4
Optical Interface
Data: channels per module
4.4.1
4.4.2
4.4.3
4.4.4
4.4.5
4.4.6
4.4.7
4.5
4.5.1
4.5.2
4.6
1 + 1 com path protection, available for all
V.24/V.28 (RS-232): up to 38.4kbit/s
V.11/X.24 (RS-422): 64kbit/s
V.35: 64kbit/s
V.36 (RS-449): 64kbit/s
G.703: 64kbit/s
Ethernet:
10/100 BaseT
WAN capacity
Protocols
Integrated alarm gathering module:
Number of external alarms per module
Auxiliary power supply for ext. contacts
Network Management System
4.6.1
Type/Name of configuration tool
4.6.2
For fault / configuration management
Yes / yes
4.6.3
4.6.4
For local / remote operation
Data communication network (DCN)
Yes / yes
4.7
Ambient Conditions:
4.7.1
Storage: ETS 300 019-1-1, class 1.2
4.7.2
Transport: ETS 300 019-1-2, class 2.2
4.7.3
Operation: ETS 300 019-1-3, class 3.1E
4.8
Power Supply
4.8.1
Operation
4.8.2
Fully redundant power supply
Schedule A: Requirements
yes
No.
No.
No.
No.
No.
No.
Mbit/s
No.
4
4
4
2
8
1
Min: 2x 2Mbit/s
Min.: IP
Min. 20
Yes
Ethernet / IP or
Ethernit / OSI
°C / % hum
-25 .. + 55 / class 1.2
°C / % hum
-25 .. + 70 / class 2.2
°C / % hum
-5 .. +45 / class 3.1E
VDC
48 / 60
(-15/+20%)
yes
SA-63
A4. TYPE TEST AND SATISFACTORY PERFORMANE REQUIREMENTS OF
MAJOR PLANT/EQUIPMENT:
1.
Type test requirement:
1.1 Following type test certificates of the equipment of similar or higher specifications (voltage &
capacity) required by the bid shall be submitted as per relevant IEC and shall be from
independent testing laboratory except Power transformer and GIS.
Type test certificates of Power Transformer shall be issued by a STL1 Member testing
organisation/laboratory in the manner as mentioned in the STL Guides or from manufacturer's
own testing laboratory. Test carried out at manufacturer's own testing laboratory must have been
witnessed and certified by Transformer testing expert from an STLMember testing organisation.
Type test certificates of 132kV Circuit Breaker shall be issued by a STL1 Member testing
organisation/laboratory in the manner as mentioned in the STL Guides.
(i)
Power Transformer
(a)
(b)
(c)
(ii)
Temperature rise test.
Dielectric tests (Induced over voltage test, Lightning impulse voltage
withstand test, Separate source voltage withstand test).
Short circuit withstand test (special test) / Calculation.
Circuit Breaker(AIS)
(a)
(b)
(c)
(d)
(iii)
Lightning impulse voltage withstand dry test.
Power frequency voltage withstand dry test.
Out of phase switching test.
Short time withstand current test.
Disconnector(AIS)
(a) Lightning Impulse voltage withstand dry test.
(b) Power frequency voltage withstand dry test.
(c) Short time withstand current test.
(iv)
Current Transformer(AIS)
(a) Short time current test.
(b) Impulse voltages withstand tests for current transformers for service in exposed
installation.
(c) Power frequency voltage withstand test.
(d) Temperature rise test.
Voltage Transformer(AIS)
(a) Temperature rise test.
(v)
1
STL: Short-Circuit Testing Liaison (Refer to http://www.stl-liaison.org/web/02_About.php).
Schedule A: Requirements
SA-65
(b) Impulse voltages withstand tests for voltage transformers for service in exposed
installation.
(c) Short circuit test
(d) Short time over voltage test
(vi)
Lightning Arrester(AIS)
(a) Power frequency voltage withstands and lightning impulse voltage withstand tests
on complete arrester housing.
(b) Operating duty test.
(c) Long duration current impulse withstand test.
(d) Residual voltage test.
(e) Pressure relief test.
(f) Artificial pollution test.
(vii)
For insulator units:
Type test certificates from independent reputed testing laboratory for insulator units
which shall include the following tests performed on all the offered types of
insulators as per IEC.
-
(viii)
Dry lightning impulse voltage withstand test;
Wet power frequency voltage withstand test;
Electro-mechanical failing load test;
Thermal mechanical performance test;
Impulse voltage puncture test;
Power arc test.
For Protective relays and Substation Automation System:
Type test certificates from independent reputed testing laboratory for
Protective relays as per IEC 61850.
Schedule A: Requirements
SA-66
Technical Specification
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 2
ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
SECTION2
ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
TABLEOF CLAUSES
2.1SCOPE
............................................................................................................................... 2/5
2.2 REFERENCES ....................................................................................................................... 2/5
2.2.1 ISO STANDARDS .................................................................................................................... 2/5
2.2.2 IEC STADARDS ...................................................................................................................... 2/5
2.2.3 BRITISH STADARDS ............................................................................................................... 2/6
2.2.4 BS EUROPEAN STANDARDS ................................................................................................... 2/7
2.3 DEFINITION OF TERMS ...................................................................................................... 2/7
2.4 STATUTORY REGULATIONS ............................................................................................. 2/7
2.5 DESIGN STANDARDS AND CODES ................................................................................... 2/8
2.5.1 GERERAL COMPIANCE WITH INTERNATIONAL STANDARDS AND CODES ............................... 2/8
2.5.2 STANDARDS NAMED IN SPECIFICATION ................................................................................ 2/8
2.5.3 HIERARCHY OF STANDARDS .................................................................................................. 2/8
2.5.4 SUBSTATION OF STANDARDS AND DESIGN CODES ................................................................ 2/8
2.6 ERECTION MARKS ............................................................................................................... 2/9
2.7CLEANING AND PAINTING................................................................................................. 2/9
2.7.1 GENERAL ............................................................................................................................... 2/9
2.7.2 SCHEDULES OF FINISH ........................................................................................................ 2/12
2.8 RATING PLATES, NAMEPLATES AND LABEL .............................................................. 2/19
2.8.1 GENERAL ............................................................................................................................. 2/19
2.8.2 RATING PLATES ................................................................................................................... 2/19
2.8.3 CIRCUIT LABELS.................................................................................................................. 2/19
2.8.4 PIPE SERVICE IDENTIFICATION ........................................................................................... 2/20
2.9 ENVIRONMENTAL PROTECTION & TROPICALISATION ........................................... 2/20
2.9.1 GENERAL ............................................................................................................................. 2/20
2.9.2 TROPICALISATION................................................................................................................ 2/21
2.10 PLATFORMS, STAIRWAYS, LADDERS AND HAND-RAILING ................................... 2/21
2.10.1 GENERAL ........................................................................................................................... 2/21
2.10.2 FOORING............................................................................................................................ 2/22
2.10.3 HAND-RAILING AND PROTECTIVE BARRIERS ..................................................................... 2/23
2.10.4 STAIRWAYS ........................................................................................................................ 2/23
2.10.5 FIXED ACCESS LADDER ..................................................................................................... 2/24
2.11 NUTS, BOLTS AND WASHERS ....................................................................................... 2/24
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/1
2.12 FORCING ............................................................................................................................ 2/24
2.13 CASTING ............................................................................................................................ 2/25
2.13.1 GENERAL ........................................................................................................................... 2/25
2.13.2 STEEL CASTINGS ............................................................................................................... 2/25
2.13.3 IRON CASTINGS ................................................................................................................. 2/26
2.13.4 ALUMINIUM BRONZE CASTINGS ........................................................................................ 2/26
2.14 GENERAL WELDING REQUIREMENTS ....................................................................... 2/27
2.14.1 GENERAL ........................................................................................................................... 2/27
2.14.2 GENERAL FABRICATION .................................................................................................... 2/27
2.14.3 WELD PROCEDURE DOCUMENTS....................................................................................... 2/27
2.14.4 WELD PROCEDURE QUALIFICATION TESTS ....................................................................... 2/28
2.14.5 WELDER'S QUALIFICATION TESTS..................................................................................... 2/28
2.14.6 STRORAGE OF WELDING CONSUMABLES ........................................................................... 2/28
2.14.7 WELDING EQUIPMENT ...................................................................................................... 2/28
2.14.8 VISUAL WELD INSPECTION ............................................................................................... 2/29
2.14.9 INTERNAL EXAMINATION .................................................................................................. 2/29
2.14.10 NON-DESTRUCTIVE EXAMINATION .................................................................................. 2/29
2.14.11 ULTRASONIC EXAMINATION ............................................................................................ 2/29
2.14.12 MAGNETIC CRACK DETECTION ....................................................................................... 2/29
2.14.13 DYE PENETRANT TESTS .................................................................................................. 2/29
2.14.14 QUALITY REQUIREMENTS FOR WELDS ............................................................................ 2/29
2.14.15 WELD REPAIRS ................................................................................................................ 2/30
2.14.16 MANDATORY INSPECTION ............................................................................................... 2/30
2.15 GALVANISED WORK........................................................................................................ 2/30
2.16 CHROMIUM PLATING ..................................................................................................... 2/31
2.17 PUMPS ............................................................................................................................. 2/31
2.18 PIPE WORK ........................................................................................................................ 2/31
2.18.1 GENERAL ........................................................................................................................... 2/31
2.18.2 INTERNAL CLEANING OF PIPES ......................................................................................... 2/32
2.18.3 PIPE SUPPORT AND ANCHORS ........................................................................................... 2/32
2.19 VALVES ............................................................................................................................. 2/32
2.19.1 GENERAL ........................................................................................................................... 2/32
2.19.2 HAND OPERATION REQUIREMENTS................................................................................... 2/32
2.20 PRESSURE VESSELS ....................................................................................................... 2/33
2.21 LUBRICATION .................................................................................................................. 2/34
2.22 OIL LEVEL INDICATORS ................................................................................................ 2/34
2.23 PRESSURE GAUGES ........................................................................................................ 2/34
2.24 THERMOMETER POCKETS ............................................................................................ 2/35
2.25 GAUGE CUBICLES AND PANELS .................................................................................. 2/35
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/2
2.26 LOCKING FACILITIES ..................................................................................................... 2/35
2.27 ELECTRICAL EQUIPMENT ............................................................................................ 2/36
2.27.1 GENERAL ........................................................................................................................... 2/36
2.27.2 ELECTRICAL EQUIPMENT ENCLOSURES ............................................................................ 2/37
2.28 CURRENT RATINGS......................................................................................................... 2/38
2.28.1 NORMAL CURRENT RATINGS ............................................................................................. 2/38
2.28.2 TEMPERATURE RISE .......................................................................................................... 2/38
2.28.3 SHORT-TIME CURRENT RATINGS ....................................................................................... 2/38
2.29 VOLTAGE RATING ........................................................................................................... 2/39
2.29.1 GENERAL ........................................................................................................................... 2/39
2.29.2 SHORT-TIME VOLTAGE RATINGS ....................................................................................... 2/39
2.30 ELECTRICAL INSULATION ............................................................................................ 2/39
2.31 INSULATION OIL ............................................................................................................. 2/40
2.32 CONTROL AND SELECTOR SWITCH ............................................................................ 2/40
2.33 PANELS, DESK AND CUBICLES .................................................................................... 2/41
2.34 INSTRUMENTS & METERS ............................................................................................ 2/43
2.34.1 INDICATING INSTRUMENTS ............................................................................................... 2/43
2.34.2 ELECTRICAL METERS ........................................................................................................ 2/44
2.35 INDICATING LAMPS AND FITTING .............................................................................. 2/44
2.36 ANTI-CONDENSATION HEATERS ................................................................................ 2/45
2.37
CONTROL AND INSTRUMENT PANEL WIREING, CABLE TERMINATIONS
AND TERMINAL BOARDS ....................................................................................................... 2/46
2.37.1 GENERAL ........................................................................................................................... 2/46
2.37.2 IDENTIFICATION OF WIRES ............................................................................................... 2/47
2.37.3 TERMINALS AND TERMINAL BLOCKS................................................................................. 2/47
2.38 CABLE BOXES AND GLANDS ......................................................................................... 2/49
2.38.1 GENERAL ........................................................................................................................... 2/49
2.38.2 ADDITIONAL REQUIREMENTS FOR COMPOUND-FILLED CABLE BOXES ............................. 2/50
2.38.3 CABLE GLANDS ................................................................................................................. 2/50
2.39 BOX-FILLING COMPOUNDS .......................................................................................... 2/51
2.40 OIL OF COMPOUND-RILLED CHAMBERS ................................................................... 2/51
2.41 JOINTS AND GASKETS.................................................................................................... 2/51
2.42 VALVES ON ELECTRICAL EQUIPMENT FLUID LINE AND VESSEL ...................... 2/52
2.43 JUNCTION AND MARSHALLING BOXES ..................................................................... 2/52
2.44 CONDUIT AND ACCESSORIES ...................................................................................... 2/53
2.45TRUNKING ......................................................................................................................... 2/53
2.46ELECTRIC MOTORS .......................................................................................................... 2/54
2.46.1 GENERAL ........................................................................................................................... 2/54
2.46.2 TYPE AND RATING ............................................................................................................. 2/54
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/3
2.46.3 INSULATION....................................................................................................................... 2/54
2.46.4 CONDITIONS OF OPERATION.............................................................................................. 2/54
2.46.5 STARTING PERFORMANCE ................................................................................................. 2/54
2.46.6 BEARINGS .......................................................................................................................... 2/55
2.46.7 ENCLOSURES AND METHOS COOLING ............................................................................... 2/55
2.46.8 ANTI-CONDENSATION HEATERS ........................................................................................ 2/56
2.46.9 TERMINALS AND TERMINAL BOXES ................................................................................... 2/56
2.46.10 EARTH TERMINAL ........................................................................................................... 2/57
2.46.11 D.C. MOTORS .................................................................................................................. 2/57
2.47MOTOR STARTERS AND CONTACTORS FOR SEPARATE MOUNTING ................... 2/58
2.48PUSHBUTTONS AND SEPARATELY MOUNTED PUSHBUTTON STATIONS ......... 2/58
2.49MINIATURE CIRCUIT BREAKERS, FUSES AND LINKS ............................................. 2/59
2.50EARTHING AND BONDING ............................................................................................. 2/60
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/4
SECTION 2
ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2.1SCOPE
This section of the Technical Specification describes the general requirements for
mechanical and electrical designs of all the plant being supplied under the
Contract, electrical aspects being covered in the another Section of the
Specification. It shall be read in conjunction with the General Conditions,
Drawings, the Schedules and other sections of the Technical Specification covering
particular aspects of the plant and in the event of conflict between the General and
Definite Contract Requirements, then the latter shall take precedence
2.2REFERENCES
Any international standards referenced in the specifications and our outdated shall be
replaced with the corresponding replacement.
2.2.1
ISO Standards
ISO68-1
ISO261
ISO262
ISO272
ISO885
ISO888
General Purpose Screw Threads
General Purpose Metric Screw Threads
Selected sizes for screws, bolts &nuts
Fasteners - hexagon products– widths across flats
General purpose bolts and screws - metric series
Bolts, screws and studs - nominal lengths, and thread lengths for general
purpose bolts
ISO965/1,2,3 General purpose Metric screw threads
ISO4759-1
Tolerances for fasteners
ISO9000
Quality management and quality assurance standards
ISO9001
Quality management systems. Requirements
2.2.2IEC Standards
60034-1
60038
60051
60055
60059
60072
60073
60079
60085
60099-4
60137
60168
60228
60269
60273
Rotating Electrical Machines - Part 1: Rating and Performance
IEC Standard Voltages
Direct acting indicating analogue electrical measuring instruments and their
accessories
Paper insulated metal sheathed cables up to 18/30 kV
IEC Standard Current Ratings
Dimensions and output series for rotating electrical machines
Coding principles for indicators and actuators
Electrical apparatus for explosive gas atmospheres
Thermal evaluation and designation of electrical insulation
Metal-oxide surge arresters without gaps for a.c systems
Bushings for alternating voltages above 1000 V
Tests on indoor and outdoor post insulators of ceramic material or glass for
systems with nominal voltages greater than 1000 V
Conductors of insulated cables
Low voltage fuses
Characteristics of indoor & outdoor post insulators for systems with nomial
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/5
60282
60296
60305
60332
60364
60376
60383
60417
60423
60433
60437
60439
604552-2
60480
60502
62052
60529
60587
60621
60644
60660
60672
60898
60947-1
60947-2
60947-3
60947-5-1
60981
61035
61084
62271-1
62271-100
62271-200
62271-203
62271-209
voltages greater than 1000 V
High voltage fuses
Unused mineral insulating oils for transformers & switchgear
Characteristics of string insulator units of the cap & pin type
Tests on electric and optical fibre cables under fire conditions
Electrical installations of buildings
Specification and acceptance of new sulphur hexafluoride
Insulators for overhead lines with a nominal voltage above 1000 V
Graphical symbols for use on equipment
Conduits systems for cable management
Characteristics of string insulator units of the long rod type
Radio interference test on high voltage insulators
Low voltage switchgear and controlgear assemblies
Solventless polymersable resinous compounds used for electrical insulation
Guideline for the checking of sulphur hexafluoride taken from electrical equipment
Extruded solid dielectric insulated power cables from 1 - 30 kV
Electricity metering equipment
Degrees of protection provided by enclosures (IP Codes)
Test methods for evaluating resistance to tracking
Electrical installations for outdoor sites under heavy conditions
Specification for high-voltage fuse links for motor circuit applications
Tests on indoor post insulators of organic mats. between 1 - 300 kV
Specification for ceramic & glass insulating mats.
Circuit Breakers for overcurrent protection for households etc.
Low voltage switchgear & controlgear-General rules
Circuit breakers
Switches, disconnectors, switch-disconnectors, etc.
Control circuit devices and switching elements
Extra heavy duty electrical rigid steel conduits
Specification for conduit fittings for electrical installations
Cable trunking & ducting systems for electrical installations
Common clauses for HV switchgear & control gear standards
High voltage alternating circuit breakers
AC metal - enclosed switchgear & control gear for 1 kV and up to including 52 kV
Gas insulated metal-enclosed switchgear for rated voltages of 52 kV and above
Cable connections for gas-insulated metal-enclosed switchgear for rated
voltages of 52 kV and above
2.2.3
British Standards
BS29
BS 182
BS 443
BS499
BS709
BS 729
BS970
BS CP 1014
BS 1224
BS1710
Spec for Carbon steel forgings
Specification for galvanised line wire for telephone & telegraphic purposes
Specification for testing zinc coatings on steel wire
Welding terms & Symbols
Method & testing fusion welded joints
Specification for hot dip galvanised coatings on iron & steel articles
Specification for wrought steels for mechanical & allied engineering
Tropicalisation
Specification for electroplate coatings of nickel and chromium
Specification for identification of pipelines & services
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/6
BS 1780
BS 1858
BS 2011
BS 2569 Pt2
BS 2600 Pt 1
BS 2765
BS 2910
BS 3858
BS3923 Pt1
&Pt2
BS 4211
Specification for Bordon tube pressure and vacuum gauges
Specification for bitumen based filling compounds
Environmental Testing
Protection of iron & steel against corrosion at elevated temp.
Radiographic examination of fusion welded butt joints in steel
Specification for dimensions of temperature detecting elements
Radiographic examination of fusion welded circumferential butt joints
Specification for sleeves for electric cables & wires
Methods of examination of fused welds and butt joints.
Specification for ladders for permanent access to chimneys, other high
structures, silos and bins
Specification for High Strength Grip Bolts
Recommendations for coatings.
BS4395-1-2
BS4479
Pts 1-9
BS 4592 Pt 1-4Industrial type flooring, walkways and stair treads
BS4604 Pt 1-2 Spec for high strength friction bolts
BS4670
Spec for alloy steel forgings.
BS 4800
Schedule of Paint Colours for building
BS 4675 Pt2 (ISO 2954) Mechanical vibration of rotating and reciprocating machinery
BS 4872 Pt 1 Fusion welding of steel
BS 5395-3
Code of Practice for the design of industrial type stairs, permanent
ladders etc.
BS 5493
Code of practice for protective coating of iron & steel structures against
corrosion
BS6072
Method for penetrant flaw detection
BS 6121-1
Specification for metallic cable glands
BS 6121-2
Specification for polymeric cable glands
BS 6121-3
Specification for special corrosion resistant cable glands
BS 6180
Code of Practice for barriers in and about buildings
BS 6231
Specification for PVC insulated cables for switch & control wiring
BS6443
Method of penetrant flaw detection.
BS7079
Preparation of steel substrates before application of paints
2.2.4
BS European Standards
BSEN287
-1&-2
BSEN2881 thru to.-8
Approval testing of welders for fusion welding
Specification &Approval of welding procedures
2.3DEFINITION OF TERMS
The definition of terms shall be as set out in the General Conditions of Contract.
2.4STATUTORY REGULATIONS
The Works and all equipment and materials forming part of this Contract shall
comply in all respects with any relevant statutory regulations, by-laws or orders
currently in force in Bangladesh.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/7
2.5
DESIGN STANDARDS AND CODES
2.5.1
General Compliance with International Standards and Codes
The Contract Works shall comply with the relevant standards as specified.
Provided there is no conflict with the standards, and unless otherwise stated, all
parts of the Works shall comply with the relevant international standards and
design codes. Where suitable international standards do not exist, internationally
accepted national standards (which ensure equivalent or higher quality than
specified standard) or other approved standards shall apply.
2.5.2
Standards Named in Specification
Although the Works shall generally comply with international standards, any
instruction in this Specification that a particular aspect of the Works shall comply
with a named code or standard shall take precedence, and that particular aspect of
the Works shall comply with the named code or standard.
2.5.3
Hierarchy of Standards
In the event of any conflict in standards, the hierarchy of standards shall be as
follows, with the standards occurring first in the list taking precedence over any
standards later in the list:
i)
ii)
iii)
iv)
Statutory regulations of Bangladesh
Standards named in the Specification
International Standards
Other standards approved by the Engineer
Where equipment is specified to a particular standard, the Contractor may supply
equipment of an equivalent standard, if approved by the Engineer.
2.5.4
Substitution of Standards and Design Codes
The Contractor may offer Works which comply with international standards or
internationally recognized national codes or standards, which differ from those
specified. However the Contractor may offer Works which comply with the
different standards or codes only if, when requested by the Engineer, he is able to
demonstrate to the Engineer's satisfaction that the Works offered are equal or
superior to that which would have resulted had the specified code or standard been
used. This substitution of codes or standards for those specified will only be
acceptable if the manufacturing organization in question has extensive experience
with the alternative code or standard offered.
Any Contractor offering Contract Works or part of those Works to standards and
codes which differ from those specified shall declare the fact to the Engineer. If
requested to do so by the Engineer, the Contractor shall supply to the Engineer, at
his own cost, two copies in English of the relevant code or standard which he
proposes to substitute for that specified.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/8
2.6ERECTION MARKS
All members comprising multipart assemblies, e.g., steel frameworks, piping
installations, etc., shall be marked with distinguishing numbers and/or letters
corresponding to those on the approved drawings or material lists. These erection
marks, if impressed, must be completed before painting or galvanising, shall be
clearly readable afterwards.
Colour banding to an approved code shall be employed to identify members of
similar shape or type but of differing strengths or grades.
2.7
2.7.1
CLEANING AND PAINTING
General
Following award of the Contract, the Contractor shall submit the name of the
proposed paint supplier and applicator, together with a quality assurance program,
for approval. All paints for the outdoor equipment on the Contract shall be
provided by one manufacturer and preferably shall be manufactured in one country
to ensure compatibility. All painting of outdoor equipment shall be carried out
strictly in accordance with the paint system manufacturer's recommendations and
the application shall be checked and approved, in writing, by an authorized
representative of the paint manufacturer.
The painting of the plant shall be carried out in accordance with the appropriate
schedule later in this Section. The work is generally covered by the Schedules but
where particular items are not referred to specifically, they shall be treated in a
manner similar to other comparable items as agreed with the Engineer.
The Contractor shall ensure that precautions are taken in packing and crating, to
avoid damage to the protective treatment during transportation to the site. Any
damage to paintwork which occurs during transport shall be made good at Site.
The schedules indicate standards of surface preparation and painting which are
intended to give a minimum life of 10 years in a severe environment, with need for
only minor remedial work in that period.
Steel sections and plate shall be free from surface flaws and laminations prior to
blast cleaning and shall not be in worse condition than ISO8501-1.
Where paint coatings are proposed for the protection of surfaces of equipment
exposed to corrosive conditions, such as plant items exposed to brine or sea water,
or immersion in liquids or wet gases, the coatings shall be formulated to be suitably
corrosion resistant and shall be high voltage spark tested at works and at Site prior
to commissioning. The test procedure shall be based on the use of a high voltage
direct current. The voltage used shall be 75% of the breakdown voltage of the
coating. This breakdown voltage shall first be separately determined using test
plates coated with the specified coating formulation and thickness. The coating on
the test plate shall also be micro sectioned by the applicator to show that it is free
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/9
from vacuoles and other defects likely to invalidate the test procedure.
If the defects revealed by the above test procedure do not exceed one per 5 m2 of
coating surface, the coating need not be re-tested after the defects have been
repaired. If the defects exceed one per 5 m2 of coating surface, the repairs shall be
re-tested after any curing is complete, and this procedure shall be repeated until the
defects are less than one per 5 m2 of coating surface. After repair of these defects,
the equipment can be placed in service without further testing.
All coatings proposed for the internal protection of domestic water storage tanks
and desalination plants shall be certified by an approved independent Authority as
suitable for use in potable water installations and shall meet the non-tainting
requirements of BS 3416.
The Engineer will consider alternative paint schemes to meet the requirements of
fabrication using modern automated materials handling systems, provided that the
Contractor is able to demonstrate that they offer the same standards of surface
protection and service life as those intended by the Schedules.
All paints shall be applied by brush or spray in accordance with the schedule,
except for priming coats for steel floors, galleries and stairways where dipping will
be permitted.
Where paint is to be applied by spray, the applicator shall demonstrate that the
spray technique employed does not produce paint films containing vacuoles.
All planished and bright parts shall be coated with grease, oil or other approved
rust preventative before dispatch and during erection and this coating shall be
cleaned off and the parts polished before being handed over.
Where lapped or butted joints from part of an assembly which is assembled or part
assembled prior to final painting, the jointed surfaces shall be cleaned free from all
scales, loose rust, dirt and grease and given one brush applied coat of zinc
phosphate primer before assembly.
Paint shall not be applied to surfaces which are superficially or structurally damp
and condensation must be absent before the application of each coat. Painting shall
not be carried out under adverse weather conditions, such as low temperature
(below 4˚C) or above 90% relative humidity or during rain or fog, or when the
surfaces are less than 3˚C above dew point, except to the approval of the Engineer
or his duly appointed representative.
Priming coats of paint shall not be applied until the surfaces have been inspected
and preparatory work has been approved by the Engineer or his duly appointed
representative.
No consecutive coats of paints, except in the case of white, shall be of the same
shade. Thinners shall not be used except with the written agreement of the
Engineer.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/10
On sheltered or unventilated horizontal surfaces on which dew may linger, more
protection will be needed and to achieve this an additional top coat of paint shall be
applied.
The schedules differentiate between "Treatments at Maker's Works" and
"Treatment at Site after Completion of Erection" but the locations at which
different stages of the treatments are carried out may be modified, always
providing that each change is specifically agreed to by the Engineer and the
painting is finished or made good at Site to the Engineer's satisfaction.
The schedules also refer to "Indoor" and "Outdoor" locations. In this context the
interiors of all buildings without air conditioning, heating or forced ventilation
shall be treated as "Outdoor".
All paint film thicknesses given are minima and refer to the dry film condition. All
thicknesses shall be determined by the correct use of approved commercial paint
film thickness measuring meters.
All outdoor painting shall be checked prior to issue of the final certificate and no
visible corrosion or spotting shall be present. Slight loss of gloss may acceptable.
In the event of visible corrosion being present, the Employer will retain the right to
withhold such an amount from the Contractor as may be necessary to repaint the
entire exterior part of the works.
The painting requirements shall be interpreted in accordance with the requirements
and recommendations of the Standards and Codes of Practice referred to and the
paint manufacturer's special instructions where applicable, colours being in
accordance with BS 1710 and BS 4800, or equivalent material standards.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/11
2.7.2
Schedules of Finishes
2.7.2.1
Schedules for Indoor Surfaces
2.7.2.1.1
General
(a)
Structural and supporting steelwork, plant items above ground, tank external surfaces.
All not above 95˚C (or 65˚C for chlorinated rubber finishes).
TREATMENT AT MAKERS
WORKS
Blast clean to BS 7079 2nd quality (SA 2.5)
profile amplitude 40-75 microns. Then apply
within 4 hours one coat (13 microns) weldable
holding primer for 12 months xmatch protection.
After fabrication is complete dress all welds,
thoroughly clean to remove corrosion products,
oil, grease and dirt and apply one coat (50
microns) of two pack epoxy zinc phosphate
primer followed by two coats two pack epoxy
micaceous iron oxide (250 microns total).
(b)
TREATMENT
AT
SITE
AFTER
COMPLETION OF ERECTION
Thoroughly clean to remove oil, grease and dirt.
Paint coats to be touched up where necessary.
Then apply one tie coat to finish (30 microns)
and one coat alkyd gloss (25 microns)
Steel floors, chequer plates, galleries, stairways, treads, kick stops.
TREATMENT AT MAKERS
WORKS
Galvanize to BS 729
TREATMENT
AT
SITE
AFTER
COMPLETION OF ERECTION
Thoroughly clean to remove oil, grease and dirt.
Where galvanizing is damaged wire brush to BS
7079 3rd quality (SA2) and apply 1 coat zinc rich
epoxy primer (50 microns).
Then apply:
1st coat etch primer
2nd coat epoxy zinc chromate
3rd coat 2 pack epoxy micaceous iron oxide (50
microns).
On galleries and stairways top surfaces apply 4th
coat non skid epoxy deck paint (30 microns).
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/12
(c)
Galvanized iron and steel requiring paint finish
TREATMENT AT MAKERS
WORKS
Galvanize to BS 729
TREATMENT
AT
SITE
AFTER
COMPLETION OF ERECTION
Thoroughly clean to remove oil, grease and dirt.
Then apply:1st coat of etch primer
2nd coat of zinc chromate primer (30 microns)
3rd coat alkyd undercoat (30 microns)
4th coat alkyd gloss (25 microns).
(d)
Stainless steel, aluminium alloys and non ferrous alloys requiring paint finish.
TREATMENT AT MAKERS
WORKS
Not Applicable
TREATMENT
AT
SITE
AFTER
COMPLETION OF ERECTION
Thoroughly clean to remove oil, grease and dirt.
Then apply:1st coat alkyd undercoat (30 microns)
2nd coat alkyd gloss (25 microns).
(e)
Bitumen dipped items
TREATMENT AT MAKERS
WORKS
Bitumen dipped.
TREATMENT
AT
SITE
AFTER
COMPLETION OF ERECTION
Thoroughly clean to remove oil, grease and dirt.
Then apply:1st coat general purpose aluminium paint
(18 microns)
2nd coat alkyde undercoat (30 microns)
3rd coat alkyd gloss (25 microns).
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/13
2.7.2.1.2
(a)
Battery Rooms (open top batteries), Chlorination Plant Rooms,
Electrolytic Cell Rooms
Steelwork
TREATMENT AT MAKERS
WORKS
Blast clean to 2nd quality BS 7079(SA2.5)
profile amplitude 40-75 microns and apply: -
TREATMENT
AT
SITE
AFTER
COMPLETION OF ERECTION
Thoroughly clean to remove oil, greaseand dirt.
Priming coat to be touched upwhere necessary.
Then apply:1st coat chlorinated rubber primer to
manufacturer's instructions
2nd coat high build chlorinated rubber
(80 microns)
3rd coat high build chlorinated rubber
(80 microns).
2.7.2.1.3
Bright Parts
TREATMENT AT MAKERS
TREATMENT
AT
SITE
WORKS
COMPLETION OF ERECTION
Coat with a mixture of oil, grease or approved Clean and polish
proprietary inhibitor.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
AFTER
2/14
2.7.2.1.4
Instrument Panels, Relay Panels, Control Panels, 400V A.C. Boards,
110VD.C. Boards, Telemetry Marshalling Kiosks, Lighting and Small
PowerDistribution Boxes, Battery Charger Cubicles, Metal Clad
Switchgear
TREATMENT AT MAKERS
WORKS
TREATMENT
AT
SITE
COMPLETION OF ERECTION
AFTER
Acid pickle or blasts clean to 1st quality BS Touch up if necessary and burnish
7079. Then apply:1st coat zinc chromate primer (30 microns)
Stop and fill. Then apply:2nd coat alkyd undercoat (30 microns)
Rub down with fine abrasive paper
3rd coat alkyd undercoat (30 microns)
Rub down with fine abrasive paper
Then apply: 4th coat alkyd matt (25 microns)
5th coat alkyd matt (25 microns)
6th coat alkyd matt (25 microns)
Total film thickness (125 microns).
2.7.2.2
Schedules for Outdoor Surfaces
2.7.2.2.1
General
(a)
Structural and supporting steelwork, plant items above ground, tank external surfaces.
All not above 95˚C (or 65˚C for chlorinated rubber finishes).
TREATMENT AT MAKERS
WORKS
TREATMENT
AT
SITE
COMPLETION OF ERECTION
Blast clean to BS 7079 2nd quality (SA2.5)
profile amplitude 40-75 microns. Then apply
within 4 hours one coat (13 microns) weldable
holding primer for 6 months protection or (25
microns) weldable holding primer for 12 months
protection. After the protection period,
thoroughly clean to remove oil, grease and dirt
and apply one coat (50 microns) of two pack
epoxy zinc phosphate primer followed by two
coats two pack epoxy micaceous iron oxide (250
microns total).
Thoroughly clean to remove oil, grease and dirt.
Paint coats to be touched up where necessary.
Then apply one tie coat to match finish (30
microns) and one coat alkyd gloss (25 microns)
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
AFTER
2/15
(b)
Steel floors, chequer plates, galleries, stairways, treads, kick stops
TREATMENT AT MAKERS
WORKS
TREATMENT
AT
SITE
COMPLETION OF ERECTION
Galvanized to BS 729
Thoroughly clean to remove oil, greaseand dirt.
Where galvanizing is damagedwire brush to BS
7079 3rd quality (SA2)and apply I coat zinc rich
epoxy primer(50 microns) Then apply:
1st coat epoxy etch primer
2nd coat epoxy zinc chromate (30microns)
3rd coat two pack epoxy micaceous iron
oxide (100 microns)
On galleries and stairways top surfaces
apply 4th coat non skid epoxy deck paint
(30 microns).
(c)
AFTER
Galvanized iron and steel requiring paint finish
TREATMENT AT MAKERS
WORKS
TREATMENT
AT
SITE
COMPLETION OF ERECTION
Galvanized to BS 729
Thoroughly clean to remove oil, greaseand dirt.
Then apply:
1st coat etch primer
2nd coat zinc chromate primer (30microns)
3rd coat alkyd undercoat (30 microns)
4th coat alkyd gloss (25 microns).
(d)
AFTER
Stainless steel, aluminium alloys and non ferrous alloys requiring paint finish
TREATMENT AT MAKERS
WORKS
Not applicable.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
TREATMENT
AT
SITE
AFTER
COMPLETION OF ERECTION
Thoroughly clean to remove oil, greaseand dirt.
Then apply:
1st coat alkyd undercoat (30 microns)
2nd coat alkyd gloss (25 microns).
2/16
(e)
Bitumen dipped items
TREATMENT AT MAKERS
WORKS
Bitumen dipped.
2.7.2.2.2
TREATMENT
AT
SITE
AFTER
COMPLETION OF ERECTION
Thoroughly clean to remove oil, greaseand dirt.
Then apply:
1st coat general purpose aluminium paint
(18 microns)
2nd coat alkyd undercoat (30 microns)
3rd coat alkyd gloss (25 microns)
Bright Parts
TREATMENT AT MAKERS
TREATMENT
AT
SITE
WORKS
COMPLETION OF ERECTION
Coat with a mixture of oil, grease or approved Clean and polish
proprietary inhibitor.
2.7.2.2.3
AFTER
Instrument Panels, Control Panels, Marshalling Kiosks, Lighting and
SmallPower Distribution Boxes and Junction Boxes etc.
TREATMENT AT MAKERS
WORKS
TREATMENT
AT
SITE
COMPLETION OF ERECTION
AFTER
Blast clean, prime, undercoat and paint in Clean and touch up as necessary
accordance with the painting schedule
for structural and supporting steelwork,
with finish coat of paint applied at
manufacturer's works
2.7.2.2.4
Water and Oil Storage Tanks - Internal Surfaces
The epoxy paint formulation shall be to the approval of the Engineer. The finished
coating shall be capable of being tested with a high voltages spark tester for
absence of pinholes and porosity.
For oil storage tanks, solvent-free epoxy paint formulation shall be used.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/17
TREATMENT AT MAKERS
WORKS
TREATMENT
AT
SITE
COMPLETION OF ERECTION
AFTER
For tanks delivered to site in plate sections, the
plates shall be blast cleaned to BS 7079 1st
quality (SA3) profile amplitude 40-75 microns
and then within 4 hours coat with a weldable
holding primer dry film thickness 25 microns
Welded Construction at Site.
After erection all welds shall be dressedto
remove rough edges and burrs and allsharp edges
shall be radiused 3 mm
Prior to painting, all surfaces shall be
sweep blast cleaned to a sound surface
free from rust and debris. Then apply
within 4 hours:
1st coat Isocyanate or amine cured epoxy
primer 25 microns
2nd coat Isocyanate or amine cured high
build epoxy (125 microns)
3rd coat Isocyanate or amine cured high
build epoxy (125 microns).
Sectional Construction
Sectional Construction
Prior to assembly all component items to be blast Touch up damaged areas as necessary.
cleaned to BS 7079 Ist quality (SA3) profile
amplitude 40-75 microns.
Then apply:Ist coat Isocyanate or amine cured epoxy primer
(25 microns). After assembly clean all surfaces
free from rust, grease and dirt. Priming coat to be
touched up as necessary. Then apply:
2nd coat Isocyanate or amine cured high build
epoxy (125 microns)
3rd coat Isocyanate or amine cured high build
epoxy (125 microns).
2.7.2.3
Radiators
Radiators shall be thoroughly cleaned and treated externally by phosphating or
other approved rust inhibiting process and given, preferably by flood painting, the
same number and type of coats specified in above. Radiators which are hot dip
galvanised to BS.729, Part 1, shall be artificially weathered and given one coat of
zinc chromate primer followed by the same number and type of paint coatings
specified in Clause. Radiators shall be painted with Munsell colour No. 5Y-7/1.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/18
2.8
RATING PLATES, NAMEPLATES AND LABELS
2.8.1
General
The Contractor shall supply and install all labels, name, rating, instruction and
warning plates necessary for the identification and safe operation of the Works.
Samples shall be submitted for the approval of the Engineer.
Nameplates or labels shall be of non-hygroscopic, non-deteriorating and
non-warping material with engraved lettering of a contrasting colour or, in the case
of indoor circuit-breakers, starters, etc, white plastic material with black lettering
engraved thereon. Items of Plant such as valves, mounted outdoors or subject to
harsh operating conditions, shall be provided with engraved chromium plated brass
or stainless steel nameplates or labels with engraving filled with black enamel.
All the above labels and plates shall be securely fixed to items of plant and
equipment with stainless steel rivets, plated self tapping screws or other approved
means. The use of adhesives will not be permitted.
Individual plant items and all relevant areas within the contract works where a
danger to personnel exists shall be provided with plentiful, prominent and clear
warning notices.
These warning notices shall draw attention to the danger or risk with words in the
language specified which attract attention and summarise the type of risk or
danger. The notices shall also carry a large symbol which graphically depicts the
type of risk.
All equipment within panels and desks shall be individually identified.
Items of Plant, such as valves, which are subject to handling, shall be provided
with nameplates with permanent inscriptions thereon.
2.8.2
Rating Plates
Each main and auxiliary item of Plant shall have attached to it in a conspicuous
position, a rating plate upon which shall be engraved all appropriate technical data
and any identifying name, type or serial number, and the requirements of the
Standard specific to the item of plant. In addition the Engineer may require to be
included details of the loading conditions under which the item of Plant in question
has been designed to operate, such as the short-time rating of switchgear.
2.8.3
Circuit Labels
Each main item of Plant shall be provided with an identification plate. The
inscriptions shall be approved by the Engineer.
In addition the device number allocated by the Engineer to each item of Plant shall
be displayed in text height 30mm on all operating mechanisms and 60mm or larger
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/19
in height on principal items of Plant, e.g. busbars, transformers etc. The same
device number shall be displayed on control cubicles in text height 10mm or larger
as may be required by the Engineer.
2.8.4
Pipe Service Identification
A colour banding scheme shall be used to identify pipe work included within this
Contract. The colours employed shall be in accordance with the painting
specification herein.
Colour bands shall be painted on each side of all valves and items of equipment in
the piping systems. The use of adhesive-backed colour bands is not permitted.
Valve labels shall be circular and fitted under the handwheel captive nut. For
check valves and small valves the Contractor may provide rectangular labels fitted
to the valve or secured close by the valve.
The inscription or "name" on each valve label shall summarise the duty of the
valve, and the number shown on each valve label shall be the number in the unified
plant valve numbering scheme.
Where the direction of flow through a valve or other device is an important
requirement for correct functioning, the body of the valve or device shall be legibly
marked with a cast on or a properly secured arrow, showing the direction of flow.
Pipework shall be provided with plentiful large painted arrows or other secure and
durable arrow markings to allow the flows of fluids around the plant to be readily
understood.
2.9
ENVIRONMENTAL PROTECTION & TROPICALISATION
2.9.1
General
All equipment shall be designed to operate in the environmental conditions
specified. Outdoor equipment shall be designed so that water cannot collect at any
point. The undersides of all tanks shall be ventilated in an approved manner to
prevent corrosion.
Where applicable, equipment should tolerate the effects of freezing and air
pollution.
Where personnel have to be in attendance frequently, or maintenance has to be
regularly carried out, permanent means weather protection or sunshades shall be
provided.
Where the performance, reliability or life of the plant would be adversely affected
by solar radiation, including the effects of prolonged exposure to ultra violet light,
suitable sunshades shall be provided. Such sunshades shall be constructed from
materials that are able to withstand the effects of the ambient conditions on site
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/20
without suffering any deterioration in material strength or effectiveness.
Sunshades need not be provided on outdoor plant or equipment provided the
manufacturer can satisfy the Engineer that the materials employed will not be
adversely affected or the temperature rise due to internal heat generation plus that
due to solar radiation will not exceed the equipment design temperature. However
equipment requiring manual operation shall be provided with sunshades to ensure
that surface temperatures will not exceed 50°C.
Sunshades shall protect plant and personnel when the sun is more than 45°C above
the horizon. They shall not impede the operation or maintenance of the plant or the
movement of ventilating air and shall include adequate artificial light as necessary.
Facilities such as lighting, lifting beams and rainwater drainage shall be provided
wherever necessary to the approval of the Engineer as an integral part of the
sunshade structure.
2.9.2Tropicalisation
In choosing materials and their finishes, due regard shall be given to the humid
tropical conditions under which equipment shall work, and good proven practices
shall be followed unless otherwise approved by the Engineer. Some relaxation of
the following provisions may be permitted where equipment is hermetically sealed
but it is preferred that tropical grade materials should be used wherever possible:
Metals: Iron and steel are generally to be painted or galvanised as appropriate.
Indoor parts may alternatively have chromium or copper-nickel plating or other
approved protective finish. Small iron and steel parts (other than stainless steel) of
all instruments and electrical equipment, the cores of electromagnets and the metal
parts of relays and mechanisms shall be treated in an approved manner to prevent
rusting.
Screws, Nuts, Springs, Etc: The use of iron and steel shall be avoided in
instruments and electrical relays wherever possible. Steel screws shall be zinc,
cadmium or chromium plated, or when plating is not possible owing to tolerance
limitations, shall be of corrosion-resisting steel. Instrument screws (except those
forming part of a magnetic circuit) shall be of brass or bronze. Springs shall be of
non-rusting material, e.g., phosphor-bronze or nickel silver, as far as possible.
Rubbers: Neoprene and similar synthetic compounds, not subject to deterioration
due to the climatic conditions, shall be used for gaskets, sealing rings, diaphragms,
etc.
2.10
PLATFORMS, STAIRWAYS, LADDERS AND HAND-RAILING
2.10.1 General
The Contractor shall provide all platforms, galleries, stairways and ladders
necessary to give access to the various sections of the plant being supplied under
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/21
this Contract. They shall provide adequate means of access for all operation,
inspection and overhaul purposes and shall be of sufficient strength to support
workmen, tools and portions of plant which may be placed on them during
overhaul and inspection periods.
Galleries, platforms and stairways shall be designed generally for a load of
7.5kN/m2 but where loads in excess of this are likely to be imposed during
operation or maintenance, the Contractor shall make due allowance for the
increased loads in the design. Particular care shall be given to their rigidity. All the
necessary supports from the floors, buildings and foundations shall be supplied
under this Contract.
Galleries and platforms around plant subject to significant expansion shall be
designed to allow for such expansion and to provide safe and adequate access for
both hot and cold conditions.
Platforms and galleries shall have a minimum width of 850 mm clear passageway
and shall be enclosed by hand-railing on both sides. In cases where there is a space
not exceeding 200 mm on one side of a passageway hand-railing need be supplied
for one side only but an edging strip shall be provided on the side without handrail.
The minimum headroom on platforms and galleries shall be 2100 mm.
Ladders will only be permitted where stairways are impractical and access is
required for maintenance.
All platforms, stairways, ladders and other accessways, shall comply with the
requirements of BS 5395 Part 3, unless otherwise stated.
As far as practical the flooring, stair treads and hand-rails shall conform to a
uniform pattern throughout the whole of the Contract Works.
2.10.2 Flooring
The flooring of all platforms, galleries and staircase treads shall consist of an
approved type of galvanised mild steel open grid flooring except in those cases
where chequer plate is specified.
Toe plates extending to a height of not less than 100 mm above the platform or
gallery level and of a thickness of not less than 6 mm shall be supplied. Any
opening which it is necessary to cut in the open grid flooring or chequer plate shall
be finished off with an edging strip similar to that on the floor panels.
The open grid flooring and stair treads shall be from an approved manufacturer and
generally in accordance with BS 4592.
The pattem of open grid flooring and chequer plate shall be uniform and laid with
the pattern in one direction.
Open grid floor panels shall be not less than 25 mm in depth and shall be fitted
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/22
neatly between kerbs and clamped with nuts and bolts in such a manner as to
permit ready removal or replacement. The design of the clamps shall be to
approval and only minimal protrusion above the floor level will be permitted.
Where chequer plate is supplied it shall be galvanised mild steel to an approved
design. No chequer plate shall be less than 10 mm thick and all plates shall be
secured to the supporting steel by galvanised countersunk screws of not less than
10 mm nominal size.
2.10.3 Hand railing and Protective Barriers
Hand railing and protective barriers shall be provided wherever necessary to
protect operation or maintenance personnel from hazards, and shall comply with
BS 6180.
Double hand-railing shall be provided unless otherwise specified. Each length shall
be joined by internal ferrules and all joints shall be neatly finished by the removal
of all burrs. The top rail shall be not less than 30 mm diameter and mounted at a
height of not less than 1100 mm from the gallery or platform level. The
intermediate rail shall be not less than 25 mm diameter and mounted at a height of
not less than 535 mm from the gallery or platform level. Hand-rails for stairways
shall have the top rail at a height of not less than 900 mm and lower rail at not less
than 420 mm above the stairway pitch line.
Tubular or solid forged stanchions shall be provided, spaced at a maximum
distance of 1750 mm, and to which hand-railing shall be firmly attached.
The stanchions shall be firmly and directly attached to the body of the platform,
gallery, stairway or ladder steelwork by bolting, and when erected shall be vertical.
They shall not be attached to toe-rails.
In designing hand-railing and its supporting stanchions particular attention shall be
paid to the provisions of BS 6180 relating to design loads and to permissible
deflections and flexibility.
2.10.4 Stairways
Where specified, main stairways shall have a minimum stair tread width of 1100
mm; other stairways shall have a minimum width of 750 mm. Wherever possible
the angle of slope of stairways shall be standardized. Angles exceeding 42˚ to the
horizontal shall not be used.
No flight of stairs shall have more than 16 risers. Where a stairway requires more
than 16 risers, each flight shall have an approximately equal number of risers and
shall be separated by a landing. Risings shall be between 190 mm and 210 mm, and
goings shall be between 220 mm and 250 mm in width. Minimum headroom shall
be 2.3 m.
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2.10.5 Fixed Access Ladders
Ladders shall comply with BS 4211. The minimum width of ladders shall be 500
mm and inclination shall be not less than 70˚, and not more than 80˚ to the
horizontal.
2.11NUTS, BOLTS, STUDS AND WASHERS
The threads and other details of fasteners shall comply with the relevant ISO
Standards for metric series fasteners.
Nuts and bolts for pressure parts shall be of the best quality steel.
Nuts, bolts, studs and washers shall be of materials most suitable for the service
operating conditions and designed to ensure the stresses arising in normal operation
shall not exceed those necessary to ensure that the specified plant life is achieved.
Nuts and bolts for incorporation in the plant are preferably to conform to ISO
Metric Coarse to ISO 272. Other sizes or threads are permitted for threaded parts
not to be disturbed in normal use or maintenance. Where the Contract includes
nuts and bolts of different standards, then the tools to be provided in accordance
with this Specification shall include spanners, taps, and dies for these nuts and
bolts.
Fitted bolts shall be a driving fit in the reamed holes they occupy, shall have the
screwed portion of a diameter such that it will not be damaged in driving and shall
be marked in a conspicuous position to ensure correct assembly at Site.
Stud holes in those parts of the plant which are subjected to heat in use shall be
adequately vented.
The threaded portion of any bolt or stud shall not protrude more than 1.5 threads
above the surface of its mating nut.
Where practicable the use of slotted head screws shall be avoided in machinery
component assemblies, hexagon socketed screws being preferred.
On outdoor equipment all bolts, nuts and washers shall be of non-rusting material
where they are in contact with non-ferrous parts in conductor clamps and fittings
and elsewhere where specifically required by the Engineer.
All washers shall be included under this Contract, including locking devices and
anti-vibration arrangements, which shall be subject to the approval of the Engineer.
Taper washers shall be fitted where necessary.
2.12
FORGINGS
The Contractor shall supply a list of all important forgings and draw up material
specifications for each one. Copies of this list and specifications shall be supplied
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to the Engineer for his use. In each case the quality and inspection requirements
shall be clearly stated.
Wherever possible steel forgings shall be in accordance with the requirements of
BS Standards 29, 970 or 4670, the equivalent ISO Standards or agreed national
standards.
Test blocks from which mechanical test pieces will be machined shall be cut from
forgings at positions to be agreed by the Engineer. On large and important forgings
several test pieces shall be taken from radial and longitudinal directions.
Forgings shall be free from cracks externally or internally, extensive non-metallic
inclusions and surface defects. The Contractor shall carry out non-destructive
testing of forgings during machining to verify that no unacceptable defects are
present.
Repairs by welding or other means shall not be undertaken on forgings at any stage
of the production cycle.
Each forging shall be suitably branded with an identification number which shall
be transferred throughout all final machining stages. The identification number
shall be marked on all documents and test certificates relative to the forging.
2.13
CASTINGS
2.13.1 General
Test pieces shall be provided from medium and large castings for all necessary
material and chemical tests which are to be witnessed by the Engineer. If required
by the Engineer any castings for rotating or highly stressed parts are to be
subjected to non-destructive testing by approved methods, including radiographic
and ultrasonic, the cost of which shall be borne by the Contractor.
All castings shall be homogeneous and free of shrinkage, pipes, undersizing,
porosity or voids. "Bum-in" repairs shall not be acceptable and no welding, filling,
interlocking or plugging of defective parts shall be done without the Engineer's
approval in writing. All repairs shall be subjected to non-destructive examination
(ultrasonics, X-rays, gamma-rays) after heat treatment. Welding repairs to castings
that will be in contact with corrosive liquids, such as seawater or brine, will only be
permitted under special circumstances.
2.13.2 Steel Castings
The Contractor shall prepare material purchasing specifications for all important
castings. Each document shall indicate fully the quality and inspection
requirements for the component casting covered. Copies of the specifications shall
be issued to the Engineer for his use.
Castings may be repaired by welding providing the approval of the Engineer is first
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obtained. The Contractor shall submit drawings, sketches or photographs showing
the location and principal dimensions of the defect together with the proposed weld
repair procedure. The maximum size of defect for which weld repair will be
permitted is:Maximum length of defect
Maximum width of defect
Maximum depth of defect
-
20 mm
10 mm
no greater than 10% of the wall thickness
Only welders who have passed an appropriate qualification test shall be employed
on the repair of castings. All repairs shall be carried out by the metal arc process.
Ultrasonic inspection shall be applied to all important castings to locate the extent
of sub-surface defects and to check the wall thickness.
All castings shall be identified by stamped or cast-on reference marks, which shall
be entered on all relevant documents and test certificates.
The Engineer may require that certain castings be examined using radiographic
techniques. The Contractor shall include for this eventuality and shall comply with
the Engineer's instructions when issued.
2.13.3 Iron Castings
Cast iron shall not be used for any part of equipment which is in tension or which
is subjected to impact, or to a working temperature exceeding 200˚C, unless
specifically approved by the Engineer. Nor shall it be used for chambers of oil
filled apparatus.
Weldable grades of iron castings may be repaired by welding provided the
approval of the Engineer is first obtained. The Contractor shall submit full details
of the proposed weld repair procedure and weld procedure qualification test prior
to making any weld repairs. The maximum size of defect for which weld repair
will be permitted is:Maximum length of defect
Maximum width of defect
Maximum depth of defect
thickness.
-
20 mm
10 mm
no greater than 10% of the wall
Test blocks shall be integrally cast on all medium and large castings.
The Engineer may require that certain castings be checked using radiographic
techniques. The Contractor shall include for this eventuality and shall comply with
the Engineer's instructions when issued.
2.13.4 Aluminium Bronze Castings
The Contractor shall prepare material purchasing specifications for all important
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castings. Each document shall indicate fully the quality and inspection
requirements for the component casting covered. Copies of the specifications shall
be issued to the Engineer for his use.
The inspection and quality requirements shall include an analysis of each cast,
mechanical testing of test pieces from each cast, pressure testing, penetrant flaw
detection and radiographic examination of selected critical areas.
Weldable grades of aluminium bronze may be repaired by welding, provided the
written approval of the Engineer is first obtained. The Contractor shall submit full
details of the proposed weld repair procedure and weld procedure qualification test
prior to making any weld repairs. The maximum size of defect for which weld
repair will be permitted is:Maximum length of defect
Maximum width of defect
Maximum depth of defect
-
20 mm
10 mm
no greater than 10% of the wall thickness
On completion of repairs, welded areas shall be ground smooth and carefully
blended into the parent material. The repaired areas shall be examined for defects
using penetrant flaw detection and radiography. Crack-like linear defects shall not
be permitted.
2.14
GENERAL WELDING REQUIREMENTS
2.14.1 General
All welding shall conform to the relevant British Standards, or other British or
National Standard Specification as agreed by the Engineer.
Where there is a conflict between Codes and/or Standards the Engineer's decision
will prevail.
2.14.2 General Fabrication
The Engineer shall be notified at least two days prior to commencement of any
assembly or fabrication work on site.
The C02 and flux-cored welding process will not be acceptable for site welding.
2.14.3 Weld Procedure Documents
Complete and fully detailed weld procedure documents shall be kept by the
Contractor and these shall be made available to the Engineer on request.
Prior to commencement of welding the Contractor shall submit to the Engineer for
approval the welding procedures to be used in the fabrication of the relevant
sections of work.
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The weld procedure documents shall be fully detailed and each shall indicate
clearly which item it is intended to cover. The procedures shall be in accordance
with the requirements of BS 499 Part 1, Appendices A-G.
2.14.4 Weld Procedure Qualification Tests
Weld procedure qualification tests shall be carried out in accordance with the
requirements of BS EN 288, or agreed National Standard for the item of Plant
under consideration.
Provided that the Contractor confirms that the basic parameters of the procedure
have not been changed since approval, the results of weld procedure qualification
tests previously carried out under the supervision of an internationally recognised
inspecting authority may be accepted by the Engineer.
The Contractor shall inform the Engineer of any proposed changes to the welding
procedures before such changes are implemented. If in the opinion of the Engineer
a further qualification test is required as a result of such changes, then the
Contractor shall perform the required test without additional charge.
The results of all tests shall be made available, for examination by the Engineer, if
required.
2.14.5 Welder's Qualification Tests
All welders and welding operators shall be qualified for the work and shall hold
current welders' qualification certificates in accordance with BS EN 287, BS 4872
or agreed National Standard for the work.
All welders' tests shall be witnessed and/or approved by the Engineer before the
welder or operator is permitted to work. The decision of the Engineer regarding the
acceptability of any test or existing qualification tests, shall be final.
Records showing the date and results of the qualification tests performed by each
welder and weld operator, together with the identification number assigned to him,
shall at all times be available for scrutiny by the Engineer.
2.14.6 Storage of Welding Consumables
Welding consumables shall be stored in a manner that will protect them from all
forms of deterioration prior to use and shall be properly identified.
Gas cylinders for use with burning or welding equipment shall be marked in
accordance with the requirements of BS 349 or IS0448. Site storage procedures for
gas cylinders will require the approval of the Engineer.
2.14.7 Welding Equipment
Any welding equipment which, in the opinion of the Engineer, is unsuitable or
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unsatisfactory for the purpose for which it is being used, shall be replaced by the
Contractor.
2.14.8 Visual Weld Inspection
Each weld shall be subjected to a stringent visual inspection and shall be free from
undercut, excessive spatter, craters, cracks, porosity and other surface
imperfections. Welds shall be of regular contour, even weld ripple and indicative
of good workmanship.
Fillet welds shall be checked for dimensional tolerance and form using a fillet weld
gauge. Fillet welds should be slightly concave in form and each leg of the weld
shall have equal length.
2.14.9 Internal Examination
The internal root bead of tube butt welds shall be examined by intrascope or other
suitable optical device.
2.14.10 Non-destructive Examination
All non-destructive examinations shall be supervised by a fully qualified and
experienced specialist appointed by the Contractor. Individual operators in each of
the respective techniques shall be qualified and trained in the respective subject
and shall have reached a standard comparable with the Certification Scheme of
Weldment Inspection Personnel in the United Kingdom.
Testing shall be in accordance with the requirements of BS 709 "Methods of
Testing Fusion Welded Joints and Weld Metal in Steel" or an agreed National
Standard.
2.14.11 Ultrasonic Examination
Ultrasonic examination of welds shall be carried out in accordance with BS 3923
Part 1 Part 2 and any other relevant British Standards or agreed National Standards.
2.14.12 Magnetic Crack Detection
Magnetic crack detection shall be carried out in accordance with BS 6072 or an
agreed National Standard.
2.14.13 Dye Penetrant Tests
Dye penetrant tests shall be in accordance with BS 6443 or any other relevant
British or agreed National Standards.
2.14.14 Quality Requirements for Welds
All welds subjected to non-destructive tests shall be entirely free from cracks or
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crack like defects, lack of root fusion, lack of sidewall fusion, root bum through, or
tailed pores. The standard for porosity and slag inclusions will be as indicated in
the agreed standards for design and welding.
2.14.15 Weld Repairs
The Engineer's approval shall be obtained prior to commencement of any repair or
rectification work.
Weld repairs shall be made to the same procedure as for the original weld. All tests
shall be repeated after the repair has been completed and reports on radiographic
and ultrasonic tests shall be marked to indicate that the report refers to a repaired
weld.
2.14.16 Mandatory Inspections
All transition welds between dissimilar materials, such as high alloy steels to
carbon steel, or austenitic steels or non ferrous materials to steels, shall be
subjected to 100% ultrasonic examination or crack detection wherever practicable.
In addition, all butt welds between dissimilar materials shall be subjected to 100%
radiographic examination.
All welds in ferritic alloy steels, e.g. having a carbon equivalent value in excess of
0.40%, and high yield-strength steels, e.g. having a yield strength greater than 300
MPa, shall be subjected to 100% ultrasonic examination and crack detection
wherever possible. In addition, all butt welds in these materials shall be subjected
to 100% radiographic examination.
A minimum of 10% of all butt welds on all classifications of work shall be
radiographically examined, unless otherwise agreed with the Engineer.
2.15
GALVANISED WORK
All materials to be galvanised shall be of the full dimensions shown or specified
and all punching, cutting, drilling, screw tapping and the removal of burrs shall be
completed before the galvanising process commences.
All galvanising shall be done by the hot dip process with spelter, not less than 98%
of which must be pure zinc and in accordance with BS 729 or BS 443 as
applicable. No alternative process shall be used without the approval of the
Engineer. Bolts shall be completely galvanised including the threads, but the
threads of nuts shall be left uncoated and shall be oiled.
The zinc coating shall be uniform, clean, smooth and as free from spangle as
possible.
Galvanised wire shall comply with the requirements of BS 182 and the thickness of
the coating and testing thereof shall comply with BS 443. Nuts and bolts and small
components shall be tested in accordance with BS 729. The Engineer may select
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for test as many components to be weighed after pickling and before and after
galvanising as he may think fit.
Galvanised steel shall be treated after galvanising with Sodium Dichromate
solution or Pretan W20 to prevent formation of white storagstan. In addition,
plastic or other non-metallic nonhygroscopic spacers shall be used between packed
members to facilitate ventilation of the zinc surface during shipping.
All galvanised parts shall be protected from injury to the zinc coating due to
abrasion during periods of transit, storage and erection. If, in the opinion of the
Engineer, the extent of the damage found on Site to a galvanised part appears to be
capable of repair the Contractor may, after receiving such agreement, attempt to
effect a repair by approved methods. The agreement to attempt the repair shall not
bind the Engineer to accept the repaired part when this is re-offered for inspection.
Should an emergency arise on Site necessitating drilling, cutting or any other
process likely to damage the protective zinc surface, this will be permitted only in
extreme circumstances and with the Engineer's express authority. In such a case,
the bared metal will be coated with an approved zinc rich paint of not less than 92
percent zinc content.
2.16
CHROMIUM PLATING
The chromium plating of those components of the Plant where specified and where
offered by the Contractor shall comply with the requirements of BS 1224.
2.17
PUMPS
Pumps should be of the centrifugal type unless strong technical or economic
reasons dictate that a positive displacement pump, either rotary or reciprocating, is
more appropriate.
Preventive and routine maintenance time should be minimised by the selection of
appropriate designs of pump, preferably those that leave casing to piping joints
intact, ie. horizontal split-casing types for large centrifugal pumps and horizontal,
back pull-out types for smaller units. Where a significant saving in floor space or
improvement of layout can be shown, a vertical pump may be acceptable.
Pumps shall be capable of continuous operation with minimum maintenance.
2.18
PIPE WORK
2.18.1 General
During the contract engineering, the Contractor shall supply to the Engineer
schedules of the pipework provided under this Contract. These schedules shall
state, for each pipework system or part of a pipework system, the design and
operating pressures and temperatures, the fluid transmitted, the piping and valve
materials, the types of valves, any corrosion allowances, the pipework design code,
insulation proposals, pipe supports and any other data relevant to the mechanical
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design of the pipework system or part of a pipework system.
All piping shall be routed to provide a neat and economical layout requiring the
minimum number of fittings. Piping shall be arranged so that full access is
provided for the operation and maintenance of equipment and so that removal or
replacement of equipment can be achieved with the minimum dismantling of
piping.
2.18.2 Internal cleaning of pipes
The Contractor is to be responsible for ensuring that the internal surface of each
pipe line is thoroughly clean both during erection and before the pipe line is placed
in commission.
The procedure adopted by the Contractor is to include the following:i)
Thorough cleaning of all internal surfaces prior to erection to remove
accumulations ofdirt, rust, scale etc., and welding slag due to site welding
before erection.
ii) Thorough cleaning of all pipework after erection by blowing through to
atmosphere toensure that no extraneous matter is left in the system.
The Contractor is to provide all
requirements.
necessary facilities for carrying out these
2.18.3 Pipe Supports and Anchors
Pipework shall be supported and anchored in an appropriate manner in accordance
with the provisions of US Standard ANSI B31.1 or the Standard to which the
pipework is designed.
The whole of the pipework and accessories included in this Contract are to be
supported and mounted in an approved manner. All necessary slings, saddles,
structural steelwork, foundation bolts, fixing bolts and all other attachments are to
be supplied.
The number and positions of all supports and the maximum weight carried by a
support is to be subject to the approval of the Engineer.
2.19
VALVES
2.19.1
General
All valves shall be suitable for the service conditions under which they are required
to operate. The design, construction and choice of materials shall take into account
all operational deviations including pressure surge and thermal shock.
2.19.2
Hand Operation Requirements
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All valve hand operating mechanisms shall be easily operable by one man. The
mechanisms shall be such that the total force at the rim of the handwheel or other
point of application of manual action shall not need to exceed 400N (normally
200N pull plus 200N push) to exercise any valve. Special attention shall be given
to the operating mechanism for large size valves with a view to ensuring that a
minimum of maintenance is required and to obtaining quick and easy operation.
All valves shall be closed by rotating the handwheels in a clockwise direction when
looking at the face of the handwheel. In cases where the handwheel is not directly
attached to the valve spindle suitable gearing shall be introduced to ensure
clockwise closing. The face of each handwheel shall be clearly marked "open" and
"shut" or "closed" with arrows indicating the direction of rotation to which they
refer.
Plastic valve handwheels will not be acceptable, except where such handwheels are
in the Employer's best interests. All valve spindles shall be fitted with indicators so
that the valve opening can be readily determined. In the case of valves fitted with
extended spindles, indicators shall be fitted both to the extended spindles and to the
valve spindles.
Valves of 50mm nominal bore and over are to be provided with indicators showing
when the valve is open or closed.
All valve hand wheels are to be fitted with nameplates complying with this
Specification.
Suitable means are to be provided to protect the operating mechanisms of all valves
against mechanical damage and dust or dirt.
Valves which it will be necessary to lock in the open or closed position are to be
provided with a non-detachable locking arrangement.
2.20 PRESSURE VESSELS
All vessels shall be designed, constructed and otherwise comply with appropriate
international or national pressure vessel design codes, unless the vessel in question
falls into one of the following groups:(a) vessels with a water containment capacity of less than 454 litres for the
containment ofwater under pressure, including those containing air, the
compression of which serves only as a cushion.
(b) hot water storage vessels heated by steam or any other indirect means when
none of thefollowing limitations is exceeded:i)
ii)
iii)
a heat input of 58kW
a water temperature of 93˚C
a nominal water containment capacity of 454 litre.
(c) vessels having an internal or external design pressure not exceeding 1.03 bar
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gauge, thisdesign pressure being not less than the maximum expected
difference that may existbetween the inside and outside of the vessel at any
time.
(d) vessels having an internal diameter not exceeding 150 mm.
(e) vessels and equipment covered more appropriately by boiler or pipework
design codes.
Should any difficulty arise in the decision as to whether a particular vessel shall
comply with a pressure vessel code, the vessel shall be "coded" unless specifically
excluded in clause U- 1 of the US ASME Boiler and Pressure Code, Section VIII,
division 1, dealing with the scope of that code.
Notwithstanding the foregoing exclusions (a) to (e), if it is stated elsewhere in the
Specification that a particular vessel shall comply with a pressure vessel design
code, then a vessel complying with a suitable design code shall be provided.
In respect of the design codes to which "coded" vessels shall comply, attention is
drawn to the provisions of this Specification relating to design codes and standards.
2.21
LUBRICATION
The Contract is to include for the supply of flushing oil for each lubrication system
when the item of plant is ready for preliminary tests and the first filling of
approved lubricants for the commercial operation of the plant.
A schedule of the oils and other lubricants recommended for all components of the
Contract Works is to be submitted to the Engineer for approval. The number of
different types of lubricants is to be kept to a minimum. Copies of this schedule
shall be included in both the draft and final copies of the operating and
maintenance instructions. In the case of grease lubricated roller type bearings for
electric motors a lithium based grease is preferred.
The Contractor is to supply at least one grease gun equipment for each type of
nipple provided. Where more than one special grease is required, a grease gun for
each special type is to be supplied and permanently labelled.
2.22
OIL LEVEL INDICATORS
Oil level indicators of approved design are to be fitted to all oil containers such as
transformer tanks etc.
The indicators are to show the level at all temperatures likely to be experienced in
service, are to be marked with the normal level at 20℃ clearly visible from normal
access levels and are to be easily dismantled for cleaning. In addition, the normal
filling level of all removable containers is to be marked on the inside.
2.23
PRESSURE GAUGES
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Pressure gauges are to comply with the requirements of BS 1780.
All pressure gauges are to be fitted with stop cocks immediately adjacent to each
gauge and all pressure gauge piping is to be fitted with an isolating valve at each
point of connection to the main system. Where pressure gauges are mounted on
panels, the stop cocks are to be suitable for the connection of a test gauge.
Gauges shall be calibrated to read pressure at the tapping point and a sealed
pressure transmitting system shall be used.
All pressure gauges are to be clearly identified by means of labels of approved type
and lettering.
All pressure gauge piping is to be of corrosion resistant steel or copper tube.
2.24
THERMOMETER POCKETS
Thermometer pockets and instrument connections of an approved pattern are to be
fitted in such positions as may be determined to suit the operation and testing of the
plant to the approval of the Engineer. A thermometer pocket is to be fitted adjacent
to each point of connection for distant remote temperature indication unless
specifically stated to the contrary. Where necessary, the pocket is to be of
approved alloy material suitable for the required service.
All thermometer pockets are to comply with the requirements of BS 2765.
2.25
GAUGE CUBICLES AND PANELS
Gauges and instruments are to be grouped whenever possible and housed in
suitable cubicles. Where circumstances do not justify cubicle accommodation,
they may be secured to flat back panels but in such cases the approval of the
Engineer is first to be obtained.
Cubicles are to be sheet metal having a thickness of 3mm. The construction shall
employ folding technique with the use of standard rolled sections or other
reinforcement where necessary. The stiffness shall be such as to prevent
maloperation of relays or other apparatus by impact. The front of the panel is to
have a smooth well finished surface and, if of the "desk" type, the desk is not to
protrude so far as to hinder the easy reading of instruments and the operation of the
controls.
2.26
LOCKING FACILITIES
Locking facilities including padlocks shall be provided under this Contract for:
(a) Control position selector switches in all positions provided.
(b) Marshalling, operating and terminal kiosks or cubicle access doors and panels.
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(c) Isolating valves in open or closed positions.
Locking facilities shall be of an approved dead latch type. Three keys shall be
supplied for each lock and all locks and keys shall be non-interchangeable.
Where a set of locks is provided under a particular section of the Plant, a group
master key shall be supplied in addition.
A schedule of locks and keys shall be submitted to the Engineer for approval.
All locks and padlocks shall be of brass and where they are fitted to switchboards
or similar cubicles shall have the visible parts chromium plated.
Where a group of locks is supplied under any part of the Contract, a rack or cabinet
of approved design shall be supplied for the accommodation of all padlocks and/or
keys while not in use. The padlocks and keys shall be engraved with an agreed
identifying code or inscription and this shall be repeated on the racks or cabinets on
engraved labels.
Where a mechanism is to be locked in a specific position, provision shall be made
at that part of the mechanism where the operating power is applied and not to
remote or ancillary linkages.
Provision for locks shall be designed, constructed and located on the equipment so
that locks will remain serviceable in the climatic conditions specified without
operation or maintenance for continuous periods of up to two years and with
suitable maintenance shall be fit for indefinite service.
2.27
ELECTRICAL EQUIPMENT
2.27.1General
The works shall be designed to ensure continuity of operation under all working
conditions obtaining at the Site as the first consideration and to facilitate
inspection, maintenance and repairs. All reasonable precautions shall be taken in
the design of equipment and of the works, to ensure the safety of personnel
concerned with the operation and maintenance of the works.
Outdoor equipment shall be designed so that water cannot collect at any point. The
undersides of all tanks shall be ventilated in an approved manner to prevent
corrosion.
Mechanisms shall be constructed to prevent sticking due to rust and corrosion, and
the bearings of exposed operating shafts shall be designed so as to prevent moisture
seeping along shafts into the interior of equipment.
Corresponding parts of similar equipment, and equipment liable to renewal, shall
be fully interchangeable and the Contractor will be required to demonstrate this
feature to the Engineer's and Employer’s satisfaction.
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All equipment shall operate without undue vibration and with the least practical
amount of noise.
All equipment shall be designed to minimise corona or other electrical discharges,
to comply with local electromagnetic compatibility (EMC) standards and in
accordance with IEC 61000.
All electrical components shall be adequately rated for their most onerous duty and
the specified ambient temperature. When equipment is mounted in panels, cubicles
etc., due account shall be taken of any heat generated by the equipment therein and
the components shall be appropriately selected, rated or derated as necessary to suit
the most onerous operating temperatures within the enclosure.
Except where a different meaning is stated in an equipment standard, the term "low
voltage" (LV) shall refer to voltages up to and including 1 kV, and "high voltage"
(HV) shall refer to all voltages exceeding 1 kV.
Fuses, circuit-breakers and other electrical switchgear components shall comply
with the relevant clauses, for low voltage ac switchgear.
2.27.2
Electrical Equipment Enclosures
Equipment enclosures for electrical equipment shall comply with IEC 60079, IEC
60529 and IEC 60947-1 as applicable. Equipment enclosures for use in hazardous
areas other than explosive gas atmosphere shall comply with National and Local
Regulations relating to this application.
Unless otherwise specified, minimum equipment enclosure classifications for
non-rotating electrical equipment shall be as follows: (a) Indoors only in
totally enclosed
rooms with provision
for limiting ingress
of dust:
IP 31
(b) Indoors, except as
noted otherwise:
IP 54
(c) Outdoors, and indoors
in areas subject to
water spray, or heavy
condensation:
IP55W
The enclosure classification of main and auxiliary cable boxes with the cable(s)
terminated shall not be less than that of the associated equipment, subject to a
minimum classification of IP54.
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2.28
CURRENT RATINGS
2.28.1
Normal Current Ratings
Current ratings in accordance with IEC 60059 shall be adopted, unless otherwise
agreed with the Engineer.
Every current carrying part of the equipment shall be capable of carrying its site
rated current continuously under the site ambient conditions as specified and shall
not be rated on the basis of air conditioned rooms even when these are specified. In
no conditions shall the specified maximum temperature be exceeded.
The current ratings specified are the continuous current ratings required at the Site,
under the specified maximum temperature conditions.
2.28.2
Temperature Rise
Full provision shall be made for solar heat gain on all outdoor apparatus and any
differential temperatures attained as a result of the impingement of solar heat.
The allowable temperature rise shall be in accordance with the relevant Standard,
except where the ambient temperature exceeds the maximum permitted in that
Standard, when the permitted temperature rise shall be reduced by one degree
Celsius for every degree Celsius the maximum ambient temperature exceeds the
maximum permitted in the Standard.
To allow for high ambient site temperatures, the allowable temperature rise for
transformers shall be reduced by a maximum of 10℃.
In such cases where the Contractor is unable to guarantee the permitted maximum
temperature reached under site conditions, taking account of solar heating, then
sunshades shall be provided to the Engineer's approval.
The maximum temperature attained by components under the most onerous service
conditions shall not cause damage or deterioration to the equipment or to any
associated or adjacent components.
The Contractor shall submit his calculations to the Engineer to prove that all plant
has been sufficiently derated to suit the site conditions and any changes required by
the Engineer shall be made at no extra cost.
2.28.3
Short-time Current Ratings
Electrical equipment shall be adequately supported and braced to withstand the
forces associated with the maximum short-circuit currents specified or pertaining,
whichever is the greater, and assuming that the inception of the short-circuit is at
such a time that gives maximum peak currents. No provision for current
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decrement shall be made unless specifically permitted by the appropriate Standard,
or elsewhere in this Specification.
Equipment shall be so constructed as to withstand the specified maximum
short-circuit currents for the time specified in the Schedules without the
temperature exceeding the specified maximum short-time temperature or value
stated in the relevant standard, under these conditions. The equipment shall be
considered as being operated at the maximum permitted continuous temperature
prior to inception of the short circuit.
The final temperature attained as a result of the passage of short-circuit current
shall not cause permanent damage, or deterioration sufficient to reduce the normal
operating characteristics below the specified or most onerous operating
requirements, whichever is the highest.
2.29
VOLTAGE RATINGS
2.29.1
Normal Voltage Ratings
Unless otherwise specifically stated, any reference to voltage rating shall be
deemed to refer to the nominal rated voltage or voltages of electrical equipment.
Standard voltage levels in accordance with IEC 60038 shall be adopted, unless
otherwise specified by or agreed with the Engineer.
All electrical equipment shall, except where otherwise specified, be capable of
continuous operation at a voltage in the range of ±15% of the nominal voltage and
at a frequency in the range of 47 to 51 Hz coincidentally without deterioration.
The temperature rise of electrical equipment continuously operating at the
specified extreme voltage and frequency shall not exceed the temperature rise
when operating at nominal voltage and frequency by more than 5℃.
2.29.2
Short-time Voltage Ratings
All electrical equipment shall be so designed such as to withstand abnormal system
voltages as required by the applicable BS, IEC or acceptable International
Standard.
2.30
ELECTRICAL INSULATION
Insulating materials shall be suitably finished so as to prevent deterioration of their
qualities under the specified working conditions. Account shall be taken of the
IEC 60085 recommendations.
Ebonite, synthetic resin-bonded laminated material and bituminised asbestos
cement-bonded panels shall be of suitable quality selected from the grades or types
in the appropriate IEC, or approved National Standard.
The insulation of all machine windings, solenoids, etc. other than those immersed
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in oil or compound, shall be of Class F materials, unless otherwise specified
elsewhere.
All cut or machined surfaces and edges of resin-bonded laminated materials shall
be cleaned and then sealed with an approved varnish as soon as possible after
cutting.
Linseed oil and untreated materials of fibre, leatheroid, presspahn, asbestos or
other similar hygroscopic types of materials shall not be used for insulation
purposes. Untreated leatheroid and presspahn may be used for mechanical
protection of winding insulation.
The use of asbestos is not permitted without the permission of the Engineer.
Wherever practicable, instrument, apparatus and machine coil windings, including
wire wound resistors, with the exception of those immersed in oil or compound,
shall be thoroughly dried in a vacuum or by other approved means and shall then
be immediately impregnated through to the core with an approved insulating
varnish. Varnish with a linseed oil base shall not be used.
No material of a hygroscopic nature shall be used for covering coils. Where
inter-leaving between windings in coils is necessary, only the best manila paper,
thoroughly dried, which permits penetration by the insulating varnish or wax, shall
be used.
Polychlorinated Biphenyl (PCB) type materials shall not be used anywhere in the
equipment or in any component.
2.31
INSULATING OIL
Insulating oil shall comply with the requirements of IEC 60296. Insulating oil
shall be provided by the Contractor for all oil-filled apparatus and 10% excess shall
be provided for topping up purposes in sealed drums. The Contractor shall provide
at no additional cost any oil treatment facilities he may require for his own use in
order to ensure that insulating oil meets the requirements of the specification.
2.32
CONTROL AND SELECTOR SWITCHES
Control switches shall be of the three position type with a spring return action to a
central neutral position and without a locking feature.
Circuit breakers shall have control switches which shall be labelled open/N/close
or (O/N/I) and arranged to operate clockwise when closing the circuit breakers and
anti-clockwise when opening them.
Control switches of the discrepancy type shall be provided where specified. Such
discrepancy control switches shall be arranged in the lines of the mimic diagram.
Such switches shall include lamps and be of the manually operated pattern, spring
loaded such that it is necessary to push and twist the switch past its indicating
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position for operation. The lamp shall be incorporated in the switch base and shall
flash whenever the position of the controlled device is at variance with the position
indicated by the control switch. Hand dressing of the control switch to the correct
position shall cause the lamp to extinguish.
Pushbutton test switches shall be provided along the control panel which will
illuminate all indicating discrepancy lamps as well as spare lamps on the control
panels. The scheme shall be complete with all necessary diodes and other
equipment required for satisfactory operation.
Switches for other apparatus shall be operated by pushbuttons, shrouded or well
recessed in their housings in such a way as to minimise the risk of inadvertent
operation.
Multi-position selector switches shall have a lockable stayput action. Each
position of the selector switches shall be suitably labelled to signify the functions
in accordance with the approved wiring diagrams. The switch handle shall be of
the pistol grip spade type to the approval of the Engineer.
It shall not be possible at any time to close any switching device from more than
one location simultaneously, and suitable lockable selector switches shall be
provided to meet this requirement. Tripping signals from all locations shall
function at all times.
Particular variations of the above requirements may be agreed with the Engineer
for special instrument or control equipment, viz. main control room desks and
panels, and electrical equipment cubicles.
The contacts of all control and selector switches shall be shrouded to minimise the
ingress of dust and accidental contact, and shall be amply rated for voltage and
current for the circuits in which they are used.
2.33
PANELS, DESKS AND CUBICLES
Unless otherwise specified, panels, desks and cubicles, shall be of floor-mounted
and free-standing construction and be in accordance with the enclosure
classification specified elsewhere. All control and instrumentation panels in any
one location shall be identical in appearance and construction. Where new panels
are supplied for existing substations, these shall match existing panels in
appearance, arrangement and devices and colour finishes.
Panels shall be rigidly constructed from folded sheet steel of 3mm minimum
thickness to support the equipment mounted thereon, above a channel base frame
to provide a toe recess.
Overall height, excluding cable boxes, shall not exceed 2.5m. Operating handles
and locking devices shall be located within the operating limits of 0.95m and 1.8m
above floor level. The minimum height for indicating instruments and meters shall
be 1.5m unless otherwise approved by the Engineer.
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Panels shall be mounted on an approved form of anti-vibration mounting whenever
necessary.
All panels, desks and cubicles shall be vermin-proof. All cable entries to
equipment shall be sealed against vermin as soon as possible after installation and
connecting-up of the cables to the approval of the Engineer.
All cubicles, desks and panels shall be provided with a natural air circulation
ventilation system. All control equipment shall be designed to operate without
forced ventilation.
For outdoor equipment, metal to metal joints shall not be permitted and all external
bolts or screws shall be provided with blind tapped holes where a through hole
would permit the ingress of moisture. For harsh environments, all nuts, bolts and
washers shall be tropicalised as appropriate in accordance with Clause 2.10.2.
Door sealing materials shall be provided suitable for the specified site conditions.
Doors shall be fitted with handles and locks. Where walk-in type panels are
supplied the door shall be capable of being opened from inside the panel without
the aid of a key after they have been locked from the outside. Hinges shall be of
the lift-off type, and shall permit the doors when open, to lie back flat so as not to
restrict access. Means shall be provided for securing the doors in the open
position.
Cubicles and cubicle doors shall be rigidly constructed such that, for example, door
mounted emergency trip contacts can be set so that mal-operation will not be
possible due to any vibrations or impacts as may reasonably be expected under
normal working conditions.
The bottom and/or top of all panels shall be sealed by means of removable
gasketted steel gland plates. Gland plates for bottom entry shall be at least 250mm
above the floor of the cubicle.
Panels shall be suitably designed to permit future extension wherever appropriate
or specified.
Each panel shall include rear access doors internal power sockets and
door-operated internal lighting, and be clearly labelled with the circuit title at front
and rear, with an additional label inside the panel. Panel sections accommodating
equipment at voltages higher than 125V (nominal) shall be partitioned off and the
voltage clearly labeled. Each relay and electronic card within panels shall be
identified by labels permanently attached to the panel and adjacent to the
equipment concerned. Where instruments are terminated in a plug and socket type
connection both the plug and the socket shall have permanently attached
identifying labels.
Instrument and control devices shall be easily accessible and capable of being
removed from the panels for maintenance purposes.
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Terminations, wiring and cabling shall be in accordance with the requirements of
this section of the specification.
For suites of panels interpanel buswiring shall be routed through apertures in the
sides of panels and not via external multicore cabling looped between the panels.
All panels, whether individually mounted or forming part of a suite, shall
incorporate a common internal copper earthing bar onto which all panel earth
connections shall be made. Suitable studs or holes to the Engineer's approval shall
be left at each end of the bar for connection to the main station earthing system and
possible future extension.
Earth connection between adjacent panels shall be achieved by extending the bar
through the panel sides and not by interconnecting external cabling.
Where intrinsically safe circuitry is routed from a hazardous area to a safe area
instrument panel, it shall be connected through Zener Barriers located in the safe
area (instrument panel) of suitable rating and mounted on an insulated earthing
busbar having facilities for connection of a separate dedicated outgoing cable to a
"clean earth" system.
Control supplies in desks, panels and cubicles shall be derived from a duplicate
standby/UPS system, except if specified otherwise in this specification. The
following alarms shall be provided to monitor the systems: voltage high, voltage
low, no volts and earth fault. The alarms shall be signaled to the Control Room.
Instruments having pressure pipe connections containing oil, water, steam or
flammable or toxic fluids shall be excluded from the Control Room.
All cubicles, desks and panels shall be painted externally with a high gloss paint of
Munsell 5Y-7/1 colour. The interiors of all cubicles, desks and panels shall be
painted matt white.
All cubicles, or panels mounted external to control and apparatus rooms shall be
fitted with thermostat controlled anti-condensation heaters.
2.34
INSTRUMENTS & METERS
2.34.1
Indicating Instruments
All indicating instruments shall be of the flush mounted pattern with dust and
moisture proof cases complying with BS 2011, Classification 00/50/04, and shall
comply with IEC 51-1.
Unless otherwise specified, all indicating instruments shall have 96mm or 144mm
square cases to DIN standard or equivalent circular cases.
Instrument dials in general should be white with black markings and should
preferably be reversible where double scale instruments are specified.
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Scales shall be of such material that no peeling or discolouration will take place
with age under humid tropical conditions.
The movements of all instruments shall be of the dead beat type. Wherever
possible, instruments shall be provided with a readily accessible zero adjustment.
2.34.2
Electrical Meters
All electrical meters shall comply with IEC 521 and, unless otherwise specified,
shall be of accuracy Class 0.2. Three-phase power measuring instruments shall be
of the three-phase unbalanced load pattern wherever the current and voltage
references permit.
Where precision grade metering is specified meters shall be calibrated to precision
grade accuracy to IEC 521. Due allowance shall be made for the errors of current
and voltage transformers with which they shall work and whose accuracy class
shall be Class 0.2.
Where commercial grade metering is specified the meters shall be calibrated to
commercial grade accuracy to IEC 521.
Meters shall be single directional and shall be fitted where required with suitable
devices for the transmission of impulses to a summator. Var-hour meters shall be
complete with phase shifting transformers as necessary.
Front of panel test terminal blocks shall be provided for all meters.
Summators shall be equipped to summate the circuits specified and shall be
equipped where required with suitable contacts for the re-transmission of impulses
to a printometer. They shall register in kilowatts the value of the impulses received
from each kilowatt-hour meter. Printometers shall be of an approved type having
the specified demand interval.
Each feeder shall be provided Main 1 and Main 2 energy meters. The energy meter
shall be 3-element, 4-wire arrangement of programmable digital type and shall
have proven performance and shall consist of different types, either from the same
manufacturer or different manufacturers. The accuracy class of the energy meter
shall be 0.2.
2.35
INDICATING LAMPS AND FITTINGS
All indicating lamps shall be adequately ventilated and as far as practicable, lamps
of a common type and manufacture shall be used throughout the Contract.
Lamps shall be easily removed and replaced where possible from the front of the
panel by manual means preferably not requiring the use of extractors.
Where specified every circuit breaker panel shall be equipped with one red and one
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green indicating lamp, indicating respectively circuit closed and circuit open and
an amber lamp for indicating 'auto-trip'. Where specified for in the lines of mimic
diagrams, indicating lamps may be of the three-lamp single-aspect type.
The variety of indicating lamps provided shall be rationalised to reduce
maintenance and spares requirements. The lamps shall be clear and shall fit into a
lamp holder. The rated lamp voltage shall be at least 20% in excess of nominal
supply voltage, whether A.C. or D.C. The lamps shall have an operating life of at
least 10,000 hours, under site conditions. In the event that other indicating devices,
such as light emitting diodes, are used in place of lamps then these shall have the
same life expectancy and performance capability as the lamps they replace.
The lamp glasses shall comply with IEC 60073 and be in the standard colours, red,
green, blue, white and amber. The colour shall be in the glass and not an applied
coating. Transparent synthetic materials may be used instead of glass subject to
the approval of the Engineer.
Where illuminated pushbuttons are used for control purposes, the illuminated
pushbuttons shall be engraved with a clear instruction such as 'push to open' or
'push to close', and the lamp shall illuminate in accordance with the above colour
code after the instruction has been carried out and the device has operated.
Unless otherwise agreed with the Engineer all lamp colours shall conform to the
following practice: Red - energised or operative position
Green - de-energised or inoperative position
Amber - fault or abnormal condition
White - healthy or normal condition
Blue - other purposes, to be used with descriptive label
Lamp test facilities shall be provided for all switchboards, control panels etc. to
enable all lamps to be tested whilst the equipment is in service. Operation of the
lamp test facility shall not cause any other device to operate.
Indication circuits shall be fused.
2.36
ANTI-CONDENSATION HEATERS
All switchboards, panels, cubicles and the like shall incorporate thermostat
controlled electric heaters capable of providing movement of sufficient heated air
to avoid condensation. The apparatus so protected shall be designed so that the
maximum permitted rise in temperature is not exceeded if the heaters are energised
while the apparatus is in operation.
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The switchboard anti-condensation heaters shall be fed from an LV single phase
and neutral supply, manually switched by a two-pole switch with red lamp,
mounted on the back of the board, panel or cubicle and buswired through the
board. Labels shall be provided on the switch stating "Heater Supply". Heater
terminals shall be shrouded and labelled "Heater".
Motor anti-condensation heaters where fitted shall be fed from an LV single phase
and neutral supply buswired through the board. The supplies shall be individually
fused and will be switched by auxiliary contacts on the contactor and isolated by
auxiliary contacts on the contactor isolator.
2.37
CONTROL AND INSTRUMENT PANEL WIRING, CABLE
TERMINATIONS AND TERMINAL BOARDS
2.37.1
General
All electrical equipment mounted in or on switchgear, panels and desks, shall have
readily accessible connections and shall be wired to terminal blocks for the
reception of external cabling.
The wiring shall comply with BS 6231 and shall be capable of withstanding
without deterioration the conditions at Site, due allowance being made for such
temperature conditions as may arise within any enclosure. The insulating material
shall be flame retardant in accordance with IEC 60332.
All wiring shall be of adequate cross-sectional area to carry prospective
short-circuit currents without risk of damage to conductors, insulation or joints.
The following classes of copper conductor, as defined in IEC 60228, shall be used
for panel wiring:
(a) Class 1 conductors up to a maximum of 0.9 mm diameter where necessary for
wire-wrapped terminations and similar techniques,
(b) Class 2 conductors except where specified otherwise,
(c) Class 5 and Class 6 conductors between points subject to relative movement.
The following minimum conductor sizes shall be used:
(a) 2.5 mm2 for current transformer secondary circuits with a rated secondary
current ofnot exceeding 1A.
(b) 1.5 mm2 except where specified otherwise,
(c) 0.5 mm2 for alarm and indication circuits with a continuous or intermittent
load currentnot exceeding 1A.
Where an overall screen is used, this shall be a metallic screen or low resistance
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
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tape, with a drain wire as above.
Wiring shall be supported using an insulated system which allows easy access for
fault finding and facilitates the installation of additional wiring.
Small wiring passing between compartments which may be separated for transport
shall be taken to terminal blocks mounted separately from those for external cable
connections.
Connections to apparatus mounted on doors or between points subject to relative
movement shall be arranged so that they are subjected to torsion rather than
bending.
Ribbon cables or similar preformed cables with plug and socket connectors may be
used for light current wiring. Plug and socket connectors shall be polarised so that
they can only be inserted into one another in the correct manner.
If so required, the Contractor shall submit for the Engineer's approval samples of
the types of wire, numbered ferrules, and terminal washers or lugs as appropriate
which he propose to use.
2.37.2
Identification of Wires
All wiring and cores in control and instrument cables shall be identified in
accordance with the associated schematic and/or wiring diagrams either by means
of discrete wire numbers or wire colours, except when an automatic or proprietary
system of wiring is used, e.g. point-to-point wiring on a mother board.
When a wire numbering system is used, it should be in accordance with a
functional marking system. Both ends of every wire and core in control and
instrument cables shall be fitted with interlocking ring ferrules of white insulating
material indelibly marked with black characters, complying with BS 3858. Heat
shrink marking sleeves may be used, but adhesive markers are not acceptable.
When plug and socket connectors are used, they shall be uniquely identified as
mating pairs and each connector pin shall be numbered. Wiring which is
permanently connected to plugs or sockets need not be identified.
Each core of multipair wiring shall be identified by colour and terminal block
identification together with an identification tracer per bundle.
Permanent identification of all terminals, wires and terminal blocks shall be
provided.
A consistent system of wiring numbering shall be used throughout the plant, and it
shall be agreed with the Engineer at the start of the Contract.
2.37.3
Terminals and Terminal Blocks
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Terminal blocks shall have separate terminals for internal and external connections,
and not more than one wire shall be connected to each terminal.
Adjacent terminals to which wires of different voltage, polarity or phase are
connected shall be separated by a protruding insulating barrier. This requirement
also applies to terminals carrying wires of the same voltage but originating from
different sources.
Trip circuit wiring and instrument transformer secondary wiring shall be connected
using hook type crimped terminations in screw clamp, spring loaded insertion type
terminals.
Where clamp type terminals are used, Class 1 and Class 2 conductors may be
terminated without lugs. Crimp lugs shall be used for Class 5 and Class 6
conductors. Means shall be provided for retaining the identifying ferrules of the
wire end when it is disconnected. Pinch screw type terminals shall not be
permitted.
Subject to approval of the Engineer, "wire-wrap", "termi-point" or equivalent
methods of terminations of single strand conductors may be used.
Wires shall be grouped on the terminal boards according to their functions.
All terminal blocks shall provide a degree of protection of not less than IP2X when
correctly installed, either inherently or by provision of insulating covers.
Terminal boards shall be mounted vertically, not less than 150mm above the gland
plates, and spaced not less than 100mm apart, on the side of the enclosure and set
obliquely towards the rear doors.
Sufficient terminals shall be provided to permit all cores on multicore cables to be
terminated. Terminals for spare cores shall be numbered and be located at such
position as will provide the maximum length of spare core. At least 10% spare
terminals shall in all cases remain after commissioning.
The tails of multicore cables shall be bound and routed so that each tail may be
traced without difficulty to its associated cable. All spare cores shall be made off to
terminals.
When two lengths of screened cable are to be connected at a terminal block (i.e.
junction box) a separate terminal shall be provided to maintain screen continuity.
In the main and local control and equipment rooms means shall be provided on the
terminal blocks of panels, desks, cubicles, etc., for testing all the instrument
circuits without the need to remove the internal or external wiring from the block.
The Contractor shall submit full details and specification of the proposed means of
termination where wire wrapping, soldering and similar methods are used. The
adopted methods shall be to the Engineer's approval.
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The Contractor shall identify all special tools, such as wire wrapping tools required
for termination, and shall make provision for their supply in sufficient numbers.
The use of pre-formed factory tested cable connections to field mounted
marshalling boxes shall be to the Engineer's approval.
2.38
CABLE BOXES AND GLANDS
2.38.1
General
Electrical equipment shall be provided with all necessary cable boxes, which shall
be complete with all required fittings. All cable boxes shall be of adequate size to
allow for the correct termination of the cable sizes required or specified, taking into
account the crossing of cores to achieve the correct phasing, and to accommodate
all cable fittings, including stress cones or other means of cable insulation grading,
if required. All cable boxes shall be designed in such a manner that they can be
opened for inspection without disturbing the gland plate or incoming cable.
All main cable boxes shall be air insulated for the termination of all types of cable
at voltages up to and including 33 kV nominal system voltage, unless otherwise
specified elsewhere in this Specification. Compound-filled cable boxes may only
be used for paper insulated cables, where specified elsewhere.
The enclosure classification of main and auxiliary cable boxes on motors with the
cable(s) terminated shall not be less than that of the associated motor, subject to a
minimum classification of IP54.
Clearance and creepage distances shall be adequate to withstand the specified
alternating current voltages and impulse voltages for service under the prevailing
site conditions. Means shall be provided for preventing accumulation of dirt, dust,
moisture, vermin or insects such as to maintain the anticipated life of the
equipment.
The terminals for 3 phase cables shall be clearly marked with the specified phase
designations to enable the cables to be terminated in the correct sequence.
Flexible connections shall be provided between cable lugs and bushings for all
cables of 300 mm2 section and greater.
There shall be no possibility of oil entering the cable box from an associated oil
filled compartment.
Inner sheaths shall be arranged to project at least 25mm above the gland plate to
avoid moisture collecting in the crutch.
All cable boxes shall be designed to withstand the high voltage d.c. cable tests
prescribed in IEC 60055, IEC 60502 or other applicable standard.
Cable lugs and terminations for the receipt of all power, control and
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instrumentation cable cores shall be provided.
Where air insulated terminations are used, the cable crutch within a cable box or
equipment panel shall be protected by the use of a heat-shrink plastic trifurcating
sleeve or equivalent placed over the cores and crutch.
The Contractor shall provide full information and instruction for his proposed
method of terminating HV cables.
Removable gasketted steel gland plates shall be provided for multicore cables. The
cable entry into the cable box shall be arranged so that there is adequate space to
manipulate the cable for glanding and termination.
When single core cables are used, particularly for currents in excess of 500A,
adequate steps must be taken to minimise the effects of eddy currents in the gland
and bushing-mounted plate.
Gland plates for externally mounted marshalling boxes shall be in the form of
removable gasketted steel plates, forming part of the underside of the box. Indoor
marshalling boxes may be fitted with gland plates on all four sides.
2.38.2
Additional Requirements for Compound-filled Cable Boxes
Cable boxes for paper insulated cables shall be complete with universal tapered
brass glands, insulated from the box in an approved manner and including an island
layer for testing purposes, together with removable shorting links.
Filling and venting plugs, where required, shall be positioned so as to avoid the
possibility of air being trapped internally and adequate arrangements shall be made
for expansion of compound, etc.
Compound-filled chambers shall be clean and dry and at such a temperature before
filling that the compound does not solidify during the filling process. Filling
orifices shall be sufficiently large to permit easy and rapid filling.
2.38.3
Cable Glands
Cable glands for extruded solid dielectric insulated cables (PVC, EPR, XLPE) shall
be of the compression type and as specified in BS 6121 Part 1.
All glands shall be provided with an earthing tag or equal facility. For cables
having conductors not larger than 4mm2 serrated washers may be used in place of
earthing tags to provide earth continuity.
Glands for armoured or screened cables greater than or equal to 240 mm2 and all
insulated glands for power cables shall be provided with an integral earthing lug.
On cable glands up to and including 40 mm nominal size, the earthing connection
shall have a short circuit rating of at least 25 kA for 1 second, and of at least 40 kA
for 1 second on larger sizes.
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Insulated glands shall be provided with removable connections for bonding across
the gland insulation. The gland insulation shall withstand a wet insulation voltage
withstand test of at least 2 kV a.c. for 1 minute.
Under conditions of severe corrosion, corrosion-resistant cable glands complying
with BS 6121 Part 3 may be used, or the Contractor may use an alternative solution
with the approval of the Engineer.
Polymeric cable glands complying with BS 6121 Part 2 may be used, but only
when terminating unarmoured cables.
Glands for MICS cables shall be to the approval of the Engineer.
2.39
BOX-FILLING COMPOUNDS
The type of compound shall be to the approval of the Engineer, who shall be
supplied with sufficient information by the Contractor. The Contractor shall supply
all compound required together with an additional quantity of not less than 10% of
normal requirements.
Where hot-pouring compounds are employed the pouring temperature shall be
verified by use of thermometers or similar instruments and the metallic case of all
joints and terminal boxes shall be adequately pre-warmed to drive off moisture.
The Contractor shall take particular care to adhere to the recommended topping-up
procedures and to ensure that no leakage or migration of the filling compound
occurs. Should leakages occur during the maintenance period the Engineer will
require the joint to be re-made at the Contractor's expense.
2.40
OIL OR COMPOUND-FILLED CHAMBERS
All joints of oil- or compound-filled fabricated chambers, other than those which
have to be broken, shall be welded and care shall be taken to ensure that the
chambers are oil-tight. Defective welded joints shall not be repaired but maybe
re-welded subject to the written approval of the Engineer.
Insulating compound shall comply with BS 1858.
The correct oil or compound filling level shall be indicated on the inside and
outside of chambers.
2.41
JOINTS AND GASKETS
All joint faces are to be flat and parallel to the approval of the Engineer and
arranged to prevent the ingress of water or leakage of oil with a minimum of gasket
surface exposed to the action of oil or air.
Oil-resisting synthetic rubber gaskets are not permissible, unless the degree of
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compression is accurately controlled. For gaskets of cork or similar, oil resisting
synthetic rubber may be used as a bonding medium.
2.42
VALVES ON ELECTRICAL EQUIPMENT FLUID LINES AND
VESSELS
Valves shall comply with the requirements of Clause 2.19.
All drain and filter valves shall be provided with gun metal adaptors suitable for
connecting a flexible hose having a screwed coupling of approved size.
Captive-screwed caps shall be provided for all such adaptors.
2.43
JUNCTION AND MARSHALLING BOXES
Junction and marshalling boxes for use in non-hazardous areas shall be of
substantial sheet aluminium anodised coating construction to prevent corrosion,
having an enclosure classification in accordance with the requirements of clause
2.27.2. They shall be fitted with external fixing lugs and finished in accordance
with the requirements of the specification for cleaning, painting and finishing. The
boxes shall allow ample room for wiring, with particular regard to the routing of
wires from the point of entry. Boxes made from aluminium shall be subject to
agreement with the Engineer.
Outdoor boxes shall have an anti-condensation finish and all boxes shall be
designed such that any condensed water cannot affect the insulation of the terminal
boards or cables. No cables shall be terminated into the top of outdoor boxes unless
specifically approved by the Engineer.
All outdoor kiosks, cubicles and panels shall be provided with sun/rain shades. All
kiosks, cubicles and panels not in air-conditioned rooms shall be provided with
thermostat controlled anti-condensation heaters.
All kiosks, and cubicles shall be fitted with door operated internal illumination
lamps.
All necessary gland plates shall be provided undrilled.
Boxes shall be complete with suitably inscribed identification labels.
Boxes for use in hazardous areas shall have all entries factory pre-drilled. Every
unused screwed entry shall be sealed by means of a tamperproof screwed plug in
accordance with IEC 60079.
Hazardous area boxes with bolted or screwed lids shall require the use of special
keys or spanners, for lid removal.
Where weatherproof types of hazardous area boxes are not available, the gaps
should be protected against the ingress of moisture, by an approved means,
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/52
compliant with local standards.
All box covers are to be arranged for padlocking and padlocks with keys shall be
supplied.
All boxes shall be provided with adequate earthing bars and terminals.
2.44
CONDUIT AND ACCESSORIES
Conduit installations shall comply with IEC standards 60364, 60621 and60981.
Installations shall also be compliant with local regulations, unless otherwise
approved by the Engineer.
All conduit and conduit fittings shall comply with IEC 60423. Unless otherwise
approved, all conduit and conduit fittings shall be threadable steel conduit with
minimum enclosure classification IP55, heavy mechanical protection and high
resistance to corrosion inside and outside.
No conduit smaller than 20mm diameter shall be used.
Standard circular boxes or machined face heavy duty steel adaptable boxes with
machined heavy type lids shall be used throughout. For outdoor mounting all boxes
shall be galvanised, weatherproof and fitted with external fixing lugs.
Where conduit is terminated so that the bare end of the conduit is exposed the
conduit end shall be fitted with a brass bush.
The use of running threads, solid elbows and solid tees will not be permitted.
Conduit ends shall be carefully reamed to remove burrs. Draw-in boxes shall be
provided at intervals not exceeding 10m in straight-through runs.
Conduit runs shall be in either the vertical or horizontal direction, unless otherwise
approved, and shall be arranged to minimise accumulation of moisture. Provision
for drainage shall be made at the lowest points of each run.
Conduits shall be supported on heavy galvanised spacer saddles so as to stand off
at least 6mm from the fixing surface.
All conduits run in any circuit are to be completed before any cables are pulled in.
Flexible metallic conduit shall be used where relative movement is required
between the conduit and connected apparatus, and a separate earth continuity
conductor shall be provided.
2.45
TRUNKING
Steel trunking may be used for running numbers of insulated cables or wires in
certain positions to the approval of the Engineer. The trunking thickness shall not
be less than 1.2 mm.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/53
Connection of conduit to trunking shall be with socket and male bush. All trunking
shall be manufactured from hot-dip zinc coated steel sheet and conform to IEC
1084.
2.46
ELECTRIC MOTORS
2.46.1
General
Motors shall comply with the requirements of IEC 60034 and IEC 60072 as
amended and supplemented by this specification.
2.46.2
Type and Rating
Except where specified otherwise or economically justified, all a.c. motors shall be
of the constant speed, cage induction type with windings adequately braced for
direct-on-line starting at the rated voltage. They shall be suitable for control by
either circuit breaker or fused contactor.
Motors shall be continuously rated, Duty Type S1. Exceptions shall be permitted
only when the intermittent or short time duty cycle can be accurately defined by
the Contractor.
Three phase a.c. motors shall be rated for the voltages specified elsewhere in the
Specification. The minimum rated output of HV motors shall comply with IEC
34-1. The maximum rated output of LV motors shall not exceed 150 kW, except
where approved by the Engineer.
2.46.3
Insulation
Motors shall be insulated with materials complying with IEC 85. All motors shall
have Class F insulation but the temperature rise shall not exceed the limits
applicable to Class B.
2.46.4
Conditions of Operation
A.C. motors shall be capable of continuous operation under the service conditions
within the Zone A voltage and frequency variations specified in IEC 34-1 Figure
13 or as covered in Clause 4.1 whichever is the most onerous.
Unless otherwise specified, the motors shall be capable of continued operation at
75% rated voltage and rated frequency for a period of 5 minutes without injurious
heating. In the event of loss of supply, all motors shall be suitable for restarting
against the full residual voltage in the motor winding during motor run-down.
2.46.5
Starting Performance
Unless otherwise specified or required, cage induction motors up to and including
40 kW shall have a starting performance better than or equal to Design N in
accordance with IEC 34 (External inertias for 50 and 60 Hz motors shall be in
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/54
accordance with BS 4999 Part 112). Cage induction motors above 40 kW shall
have a starting performance better or equal to Design D in accordance with BS
4999 Part 112. The starting current at full voltage shall not exceed 6 times full load
current.
The starting torque at 80% voltage shall be adequate for starting the driven load
under the most arduous conditions, such as open fan vane or open pump discharge
valve. The accelerating torque at any speed and 80% rated voltage shall be not less
than 10% of motor rated torque. In any event the motor starting torque at 100%
rated voltage, and at all speeds between standstill and the speed at which
breakdown torque occurs, shall be not less than 1.7 times the torque obtained from
a load curve which varies as the square of the speed and is equal to 100% motor
rated torque at rated speed.
The margins between the torques of the motors and driven plant shall include
suitable allowances for impeller wear, fouling etc. during the life of the plant.
Electric motors shall be suitable for two successive starts with the motor already at
full load working temperature, subject to the motor being permitted to decelerate to
rest under operating conditions between successive starts.
After a cooling period of 30 minutes at rest another starting sequence of two
successive starts shall be permissible.
2.46.6
Bearings
The type of bearings used in the motor shall be fully compatible with those used in
the driven equipment.
The type of bearing, bearing numbers and regressing interval shall be stamped on
each motor rating plate.
Bearings shall comply with the applicable ISO standards.
Bearings shall be designed to exclude the ingress of dust and water and sealed to
prevent leakage of lubricant along the shaft.
2.46.7
Enclosures and Methods of Cooling
The degree of enclosure protection for motors shall be as follows unless otherwise
specifically approved by the Engineer:
- IP54 for indoor locations not subject to hosing.
- Not less than IP 55W for outdoor locations, and indoor locations subject to hosing.
- Where motors are exposed to solar radiation, sunshades shall be fitted, if
required by the manufacturer to meet his guarantees.
The cooling classification for motors shall be as follows unless otherwise
specifically approved by the Engineer:
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/55
- IC4AlA1 or IC5AIA1 for LV motors, or IC4AIAO for small power LV motors.
-IC4AlAl, IC5AlAI, IC6A1A1 or IC7AlW7 for HV motors.
-Ferrous metals should be used for the frames and end shields of all ratings of
motors.
Aluminium and its alloys shall only be used when the manufacturer can
demonstrate that such materials are entirely suitable for the particular application at
its installation location.
Fans of identical motors shall be interchangeable without affecting motor balance.
2.46.8
Anti-condensation Heaters
To minimise condensation in all outdoor 400V and intermittently used 400 V
motors when out of service, heaters of an approved type and rating, suitable for
operation from a 230 V a.c. single phase supply, shall be fitted inside the lower
half of the stator frame.
The control of anti-condensation heaters shall be so arranged that they are normally
energised when the motor is not running.
2.46.9
Terminals and Terminal Boxes
Winding terminations shall generally comply with BS 4999 Part 145. Separate
non-compound filled, terminal boxes shall be provided for each of the following,
as applicable:
(a) Main (line) connections.
(b) Star point connections.
(c) Anti-condensation heater connections.
(d) Instrumentation and alarm devices.
All terminal boxes with the cables terminated shall have an enclosure classification
not less than that of the motor itself. All terminal boxes shall be of an adequate size
for the satisfactory termination of the cable(s) required or specified, including all
applicable termination components.
All HV terminal boxes shall be provided with a desiccant indicator, externally
sealed.
Terminals and terminal leads shall be to approval and shall be substantially
designed for connection to a system having the symmetrical short circuit rating of
the source switchboard, as limited by fuses, where applicable.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/56
The clearances and creepage distances shall apply also to insulated terminals and
connectors.
Porcelain terminal bushings and insulators shall not be used.
Main and star point terminal boxes of HV motors shall be of steel. Cast iron may
only be used for LV motor terminal boxes and auxiliary terminal boxes.
Star point terminal boxes shall only be provided where required to accommodate
neutral end current transformers and shall be positioned opposite the main terminal
box.
Main HV terminal boxes at voltages exceeding 7.2 kV (Um) shall be of a type
which restricts internal faults to earth faults only. Where pressure relief terminal
boxes are used, they shall be designed to relieve the products of an internal fault
safely to the outside, and not into the interior of the motor.
Provision shall be made for earthing the cable armour and the cable insulation
screens, where applicable, in accordance with the cable termination method being
used.
In auxiliary cable boxes either stud terminals or clamp terminals shall be provided.
The anti-condensation heater terminal box shall have a warning label adjacent to it,
stating "Motor heater - terminals live".
2.46.10
Earth Terminal
All motors shall be provided with a means of earthing the frame, which shall be to
the approval of the Engineer.
2.46.11
D.C. Motors
D.C. motors which are to operate from batteries shall be capable of operating under
the service conditions at any voltage in the range of 80% to 110% of the nominal
value.
Motors of the constant speed type shall be designed to operate with a permanent
series resistor of suitable rating and with a contactor such that starters with tagged
resistors are not required.
All d.c. motors shall be provided with brushgear which does not require to be
moved to suit load conditions.
2.47
Motors connected to rectifier equipment shall meet the conditions of supply
voltage and frequency specified for a.c. motors. Where necessary, rectifier
equipment shall be fitted with a current limiting device.
MOTOR STARTERS AND CONTACTORS FOR SEPARATE
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/57
MOUNTING
In special cases for motors below 30 kW, and non-essential non-plant auxiliaries,
such as roller shutter doors, and where approved by the Engineer, separately
mounted starters for motors may be provided. Each such motor starter shall be
equipped with two or three pole control gear, as appropriate, for direct-on-line
starting and shall be complete with a fully shrouded lockable isolating switch,
mechanically interlocked with the means of access.
All starters shall be supplied by one manufacturer, except where otherwise
approved by the Engineer.
Contactors shall be of robust design and shall comply with IEC 60947.
All contactors and their associated apparatus for minor motors shall be capable of
operating without overheating for all specified motor operating conditions, and
including for a period of five minutes at normal frequency if the supply voltage
falls to 80% of nominal voltage.
For motors up to 30kW rating motor starters shall be provided with direct
connected thermal overload and phase failure industrial pattern protection tripping
devices, integral with the motor contactor. Phase failure protection shall operate
with out-of-balance currents not exceeding 85% of motor full load current.
Separate contacts for a remote trip alarm shall be provided, and connected up if
required.
For motors above 30kW starters shall not be wall mounted but included in a
switchboard, except with the approval of the Engineer. For such circuits motor
protection relays with a more accurate and easily adjustable overload setting shall
be used, which are sensitive to out-of-balance currents not exceeding 20% of full
load, and shall include instantaneous earth fault elements. Alternatively,
instantaneous earth fault protection may be incorporated in the motor circuit
breaker. The earth fault protection shall not operate for unbalanced current surges
during motor starting.
2.48
PUSHBUTTONS
STATIONS
AND
SEPARATELY
MOUNTED
PUSHBUTTON
Pushbuttons, which may be of the illuminated or non illuminated type, shall be
shrouded or well recessed in their housings in such a way as to minimize the risk of
inadvertent operation.
In instances where "enable" pushbuttons are required they shall be electrically
interlocked with the normal control such that deliberate operation of the "enable"
push-button is required before the normal control can take place.
The colour of pushbuttons shall be as follows:
- When mounted on pushbutton stations adjacent to running plant the stop button
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/58
shall be coloured red and the start button coloured green.
- When mounted on the front of the contactor panel the stop button shall be
coloured red and the start button coloured green.
- When mounted on panels or desks with adjacent indication lights both buttons
shall be coloured black, unless required otherwise by the Engineer.
Loose pushbutton stations, unless supplied as weatherproof free standing
enclosures, shall be of the metalclad weatherproof type suitable for wall or bracket
mounting with a minimum enclosure classification of IP55. All outdoor mounted
pushbutton stations shall incorporate a protective cover or guard (e.g. toughened
glass door) to prevent inadvertent operation.
Control stations shall be clearly labeled showing the duty or drive to which they
are applicable. Location of ammeters shall be agreed with the Engineer.
Pushbuttons used on covered desks, panels etc. may of necessity require to be of
special types (e.g. miniature, illuminated). The specifications and requirements for
these special pushbuttons shall be agreed with the Engineer.
Emergency stop pushbuttons shall be provided adjacent to all motors and
machinery with exposed moving parts, couplings etc. to prevent danger, and on
main and local control panels. These pushbuttons shall have a large "mushroom"
head, be coloured red and incorporate a protective cover or guard to avoid
accidental operation. These buttons shall automatically lock in the depressed
position, requiring twist or key resetting. Contacts shall be provided to cause
tripping of the associated circuit, prevent restart of the circuit and bring up an
alarm in the Central Control Room.
Stop pushbuttons mounted local to motors shall trip the associated circuit breaker
or contactor regardless of the control position selected.
The contacts of all pushbuttons shall be shrouded to minimize the ingress of dust,
and accidental contact, and shall be amply rated for voltage and current for the
circuits in which they are used.
2.49
MINIATURE CIRCUIT BREAKERS, FUSES AND LINKS
Facilities shall be provided for protection and isolation of circuits associated with
protection, control and instruments. They shall be of approved type and grouped, as
far as possible, according to their functions. They shall be clearly labeled, both on
the panels and the associated wiring diagrams.
Facilities shall be provided to enable the control circuits for any circuit-breaker to
be individually isolated for maintenance purposes.
Facilities for protection and isolation of control and tripping circuits are preferably
to be mounted on the outside of control panels in approved positions.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/59
All fuses shall incorporate HRC cartridges to BS 88 or IEC 60269.
Fuse holders shall be designed to lock the cartridges firmly into position without
the use of screw clamping devices.
Miniature circuit-breakers (MCB's) shall comply with IEC 60898.
Where MCB's are used on control, protection and alarm supplies, tripping shall
cause an alarm to be displayed.
2.50
EARTHING AND BONDING
The main earthing conductors for connection to all electrical equipment, cables,
motors, panels, etc., shall be provided for connection to the main earthing system.
All non-current carrying metal parts of electrical equipment shall be bonded to an
earth terminal or terminals mounted on the equipment and readily accessible.
All equipment terminals provided for an external earth connection shall be
identified by indelible means unless such terminals are directly and visibly
mounted on metallic equipment frames or earth bars, when such marking may be
omitted.
Identification marks for earth terminals shall comprise the colours green/yellow in
combination or a reproduction of the symbol no. 5019 in IEC 60417.
Assemblies containing electrical equipment, including switchboards, control
boards and control desks, shall be provided with a separate copper earth bar
running the length of the assembly. All metal parts and the earth terminal or
terminals shall be bonded to this earth bar. Earthing connections shall not depend
upon the bolting of steel/steel joints between adjacent panels or cubicles.
Earth bars shall be of adequate size and suitably supported and braced to carry the
rated short circuit current for the associated electrical circuits for the rated shortcircuit current duration, without damage or excessive heating likely to damage
joints, associated or adjacent components.
Switchgear and control gear assemblies shall be provided with two or more earth
terminals unless otherwise specified. The copper earth bar shall be sized to
withstand the maximum system earth fault current for three seconds without
deterioration.
The size of the copper earth bar in control panels, control desks or similar
enclosures containing low voltage apparatus shall be such as to comply with the
specified requirements for withstanding prospective short-circuit currents. The size
of this bar shall be a minimum of 100 mm2 cross-sectional area, providing that
sufficient mechanical integrity is provided by adequate supports and terminals, and
also providing this size is not less than the size of the largest incoming power
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/60
supply conductor.
The metal cases of all instruments, relays and the like shall be connected to the
panel earth bars by copper conductors of not less than 1.5 mm2 cross-sectional
area, or by other means to the approval of the Engineer.
If the plant contains electronic equipment which is vulnerable to possible
conductive interference, or if the equipment generates electrical noise, which could
interfere with other plant or equipment, then separate earths may be supplied and
the actual means of interconnecting with the station earth system shall be agreed
with the Engineer.
SEC 02: ANCILLARY MECHANICAL AND ELECTRICAL APPARATUS
2/61
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 3
HV AIR INSULATED SWITCHGEAR EQUIPMENT
HV AIR INSULATED SWITCHGEAR EQUIPMENT
TABLE OF CLAUSES
3.1
SCOPE .......................................................................................................... 3
3.2
REFERENCES ............................................................................................. 3
3.2.1
IEC STANDARDS ........................................................................................................ 3
3.2.2
BRITISH STANDARDS ................................................................................................. 4
3.3
DESIGN PRINCIPLES ................................................................................ 4
3.3.1
GENERAL REQUIREMENT .......................................................................................... 4
3.3.2
AVAILABILITY FOR MAINTENANCE, REPAIR, EXTENSIONS, TESTING ........................ 5
3.4
OUTDOOR HV SWITCHGEAR .................................................................. 5
3.4.1
SWITCHGEAR - DESIGN AND PERFORMANCE ............................................................. 5
3.4.2
CURRENT RATINGS .................................................................................................... 6
3.4.3
CORONA ..................................................................................................................... 6
3.4.4
LOCAL, REMOTE AND SUPERVISORY CONTROL ......................................................... 7
3.4.5
HVAC CIRCUIT-BREAKERS ....................................................................................... 7
3.4.5.1
GENERAL .................................................................................................................. 7
3.4.5.2
OPERATING DUTY AND PERFORMANCE .................................................................... 7
3.4.5.3
CONSTRUCTIONAL FEATURES ................................................................................... 8
3.4.5.4
SULPHUR HEXAFLUORIDE GAS (SF6 GAS) ............................................................. 10
3.4.5.5
INSULATORS............................................................................................................ 10
3.4.5.6
MANDATORY MAINTENANCE EQUIPMENT .............................................................. 11
3.4.5.7
OPERATING MECHANISM AND CONTROL ................................................................ 11
3.4.5.8
SUPPORT STRUCTURES ........................................................................................... 13
3.4.5.9
TERMINAL PADS ..................................................................................................... 13
3.4.5.10
FITTINGS AND ACCESSORIES .................................................................................. 13
3.4.5.11
TESTS ...................................................................................................................... 13
3.4.5.12
TECHNICAL PARAMETERS ....................................................................................... 14
3.4.6
DISCONNECTORS AND EARTH SWITCHES ................................................................ 14
3.4.6.1
GENERAL ................................................................................................................ 14
3.4.6.2
OPERATING DUTY AND PERFORMANCE .................................................................. 14
3.4.6.3
CONSTRUCTIONAL FEATURES ................................................................................. 15
3.4.6.4
OPERATION ............................................................................................................. 17
3.4.6.5
TESTS ...................................................................................................................... 19
3.4.6.6
TECHNICAL PARAMETERS ....................................................................................... 19
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/1
3.4.7
INSTRUMENT TRANSFORMERS ................................................................................. 19
3.4.7.1
GENERAL ................................................................................................................ 19
3.4.7.2
TECHNICAL AND CONSTRUCTIONAL REQUIREMENTS ............................................. 19
3.4.7.2.1
COMMON FOR ALL INSTRUMENT TRANSFORMERS .................................................. 19
3.4.7.2.2 CURRENT TRANSFORMERS (CT) ...................................................................................... 20
3.4.7.2.3
VOLTAGE TRANSFORMERS ...................................................................................... 21
3.4.7.3
TYPE TESTS ............................................................................................................ 22
3.4.7.4
ROUTINE TESTS ...................................................................................................... 22
3.4.7.5
TECHNICAL PARAMETERS ....................................................................................... 22
3.4.8
SURGE ARRESTERS .................................................................................................. 23
3.4.8.1
GENERAL ................................................................................................................ 23
3.4.8.2
OPERATING DUTY AND PERFORMANCE .................................................................. 23
3.4.8.3
CONSTRUCTIONAL FEATURES ................................................................................. 23
3.4.8.4
FITTINGS AND ACCESSORIES .................................................................................. 24
3.4.8.5
TESTS ...................................................................................................................... 25
3.4.8.6
TECHNICAL PARAMETERS ....................................................................................... 25
3.4.9
NEUTRAL GROUNDING RESISTORS .......................................................................... 25
3.4.10
BUSBARS, CONDUCTORS AND CONNECTIONS ......................................................... 25
3.4.10.1
TUBULAR BUS CONDUCTORS .................................................................................. 26
3.4.10.2
FLEXIBLE BUS-BARS AND EARTHWIRE ................................................................... 26
3.4.10.3
CLAMPS & CONNECTORS ........................................................................................ 28
3.4.10.4
SPACERS ................................................................................................................. 30
3.4.11
INSULATORS, BUSHINGS, BUSES AND HARDWARE.................................................. 30
3.4.11.1
BUSHINGS AND SUPPORT INSULATORS ................................................................... 30
3.4.11.2
STRING INSULATORS & HARDWARE........................................................................ 32
3.4.12
INTERLOCKING FACILITIES ..................................................................................... 36
3.4.13
AUXILIARY SWITCHES AND CONTACTORS ............................................................... 37
3.6
INTERFERENCE WITH EXISTING EQUIPMENT ............................... 38
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/2
SECTION 3
HV AIR INSULATED SWITCHGEAR EQUIPMENT
3.1
SCOPE
These clauses describe the General Technical Requirements for the new, 132kV
and 33kV outdoor, open terminal circuit breakers & general switchyard equipment,
and shall be read in conjunction with the Project Requirements, Schedules and
Drawings in the specification.
The Contractor shall demonstrate that the switchgear has been designed, built and
installed in accordance with the relevant international standards and the
specification. It shall also operate and perform on a site in accordance with the
requirements of the specification and in the environment defined therein.
The design shall be proven by the submission of test certificates at the time of
Bidding covering all specified tests deemed to be pertinent to the plant and to the
conditions in which it will operate.
The requirement for switchgear spares, tools and appliances, including test,
maintenance and handling equipment shall be as stated in the Bid document. All
devices necessary for operation and earthing shall be provided within the Contract
Price.
Installation, testing and Commissioning of all switchgears shall be done by the
Switchgear Engineer(s) of the switchgear(s) manufacturer(s).
3.2
REFERENCES
Any international standards referenced in the specifications and our outdated shall
be replaced with the corresponding replacement.
3.2.1
IEC Standards
IEC 60060
High Voltage test techniques
IEC 60071
Insulation Co-ordination
IEC 60099
Surge arresters
IEC 60044-1
Instrument Transformer-Part 1: Current transformers
IEC 60044-2,
Instrument Transformer-Part 2: Voltage transformers
IEC 60044-5
Instrument Transformer-Part
transformers
IEC 60273
Characteristics of indoor and outdoor post insulators for
systems withnominal voltages greater than 1000V.
IEC 60305
Insulators for overhead lines with a nominal voltage above
1000V - Ceramic or glass insulator units for ac systems Characteristics of insulator units of the cap and pin type.
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
5:
Capacitive
Voltage
3/3
IEC60376
Specification of technical grade sulfur hexafluoride (SF6) for use
inelectrical equipment
IEC 60383
Insulators for overhead lines with a nominal voltage above
1000V
IEC 62155
Hollow pressurized and unpressurized ceramic and glass
insulators for use inelectrical equipment with rated voltages
greater than 1000 V
IEC 62271-1
HV switchgear and controlgear-part1: common specifications
IEC 62271-100
HV switchgear and controlgear–part100: AC circuit breakers
IEC 62271-102
HV switchgear and controlgear-part102: AC disconnectors
and earthing switches
IEC 62271-200
A.C. metal-enclosedswitchgear and controlgear for rated
voltages above 1 kVand up to and including 52 kV
3.2.2
British Standards
BS 7884
Specifications for hard-drawn copper and copper cadmium
conductors for overhead power transmission purposes
BS EN 60383-2
Insulators for overhead lines with voltage greater than 1000V.
BS 159
Specifications for HV busbars and busbar connections
BS 215S
Specifications for aluminium conductors for overhead
transmission
BS EN 13600
Specifications for high conductivity copper tubes for electrical
purposes
BS 2898
Specifications for wrought aluminium for electrical purposes.
Strip withdrawn or rolled edges.
BS 3288
Insulator and conductor fittings for overhead power lines.
BS 3938
Current Transformers
BS 6651
Lightning Protection
BS 7354
Code of practice for design of HV open terminal stations.
3.3
DESIGN PRINCIPLES
3.3.1
General Requirement
The normal operations will be effected from the Naional Load Dispatching Centre
(NLDC) atAftabnagar. The bidder shall take into consideration the unmanned
operation of the substation in his design (No operators are necessary in the new
substation control rooms where Substation Automation System considered).
Control facilities shall be simple and clearly designated with the respective
function and instructions on operation and maintenance shall be unambiguous.
The following provisions shall be made for control and indications:-
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/4
Control cubicle local to equipment - control of circuit breakers, disconnectors and
earthing switches where power operated, complete with electrical indications,
mimic diagram, gauges and alarm annunciator.
Remote panel in the control room on each Substation Site - control of circuit
breakers, disconnectors and line side earthing switches where power operated with
position indication in each instance.
Supervisory control from NLDC-provision of control of circuit breakers and
disconnectors switches where power operated, with position indication in each
instance.
All necessary local/remote and remote/supervisory control relays, interposing
relays and selector switches are to be provided as part of this Contract.
Circuit identifying labels shall be fitted at the front and rear of each individual
circuit assembly and on the local control cubicle.In case of labels not visible when
standing on the floor, additional name plate shall be fixed at a suitable location.
A single line diagram shall be marked along each bay showing the location of all
items of switchgear.
In the event of leakage from any compartment, equipment shall withstand rated
voltage with SF6 at atmospheric pressure.The insulation levels shall be able to
withstand basic test voltages in accordance with the relevant standards for
Synchronising Operation for Breakers.
Busbar connections and enclosures shall be designed to absorb the effects of
thermal expansion without application of stress to the supporting structure.
3.3.2
Availability for Maintenance, Repair, Extensions, Testing
Maintenance, Repair or Extension (MRE) and HV Testing on one busbar with
directly connected apparatues shall be possible with the other busbar in normal
operation.
MRE Testing on one swithgear bay shall be possible with all other switchgear bays
in normal operation on one busbar.
MRE Testing on/of buscoupler bay shall be possible with one busbar at the time in
normal operation and all switchgear bays in normal operation.
Maintenance access to each module shall be possible without necessitating the
outage of adjacent modules.
3.4
OUTDOOR HV SWITCHGEAR
3.4.1
Switchgear - Design and Performance
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The switchgear shall be suitable for outdoor location and capable of continuous
operation under the climatic conditions existing on site. It shall be designed to
comply with this Specification and relevant IEC and British Standards where
applicable.
In all cases the ancillary plant necessary to complete installation of the equipment
shall be included in the Contract.The disposition of plant in any substation is to be
such that the operation of any item of plant under the specified service conditions,
shall in no way create a condition that could adversely affect the performance of
adjacent circuit breakers or any associated equipment.
The Contractor is to ensure that the complete substation installation will satisfy the
requirements of this Specification and the appropriate Standards in respect of
insulation, fault levels, mechanical stress etc., and any additional equipment found
to be necessary to meet these requirements shall be deemed to have been included
in the Contract Price.
The layout and design of plant and equipment on substation sites shall make
provision for the future extensions shown on the layout drawings and shall provide
for ready access for operation, maintenance and extension whilst the remaining
sections of equipment are alive. Electrical clearances provided between isolated
equipment and nearest live metal work shall not be less than the distance data as
mentioned in sub-clause 1.2.3 of Section -1 of this specification (vol 2 of
3).Insulation creepage distances shall not be less than 25mm per kV rated voltage
between phases.
The Contractor shall be responsible for ensuring that insulation co-ordination in
accordance with recommendation of IEC 60071 is achieved. Dynamic and
temporary over voltages shall be assumed to be in accordance with normally
accepted IEC levels and subject to approval of the Engineer.
3.4.2
Current Ratings
Every current-carrying part of the switchgear including current transformers,
busbars, connections, contacts and joints shall be capable of carrying its specified
rated current at rated frequency continuously, and in no part shall its temperature
rise exceed that specified in relevant standards.
Every part of the switchgear shall also withstand, without mechanical or thermal
damage, the instantaneous peak currents and rated short time current pertaining to
the rated breaking capacity of the circuit-breaker.
3.4.3
Corona
Equipment shall be designed so as to minimise corona or other electrical discharge
and radio interference. The Contractor is to confirm and ensure adequacy of design
in terms of corona performance. Ion current density shall be less than 20 na/sqm at
ground level. Tests for corona and radio interference shall be carried out by the
Contractor as per relevant IEC standard. The requirements regarding external
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corona and RIV as specified for any equipment shall include its terminal fittings
and the equipment shall be factory tested with the connectors in position. In case
the connector is not available then equivalent connector may be used. If corona
rings are required to
meet these requirements they shall be considered as part of that equipment and
included in the scope of Work.
3.4.4
Local, Remote and Supervisory Control
Circuit breakers and motorised disconnectors shall be electrically controlled
locally, remotely and by supervisory telecontrol.Position indication of these
devices shall be provided on their operating mechanisms and the Contractor shall
include the supply and fitting of the necessary auxiliary switches for remote
position indication.
For supervisory telecontrol, the interface between the telecontrol control equipment
and the control equipment being provided under this Contract shall be as specified
in Section 10.
3.4.5
HVAC Circuit-Breakers
3.4.5.1
General
The circuit breakers and accessories shall conform to relevant IEC: 62271-100,
IEC: 60694 and other relevant IEC standards except to the extent explicitly
modified in the Specification.
The circuit breakers shall be sulphur hexafluoride (SF6) type only. The 36kV
circuit breakers shall be vacuum type only.
The circuit breaker shall be complete with terminal connectors, operating
mechanism, control cabinets, piping, interpole cable, cable accessories like glands,
terminal blocks, marking ferrules, lugs, pressure gauges, density monitors (with
graduated scale), galvanised support structure for CB and control cabinets, their
foundation bolts and all other circuit breakers accessories required for carrying out
all the functions the CB is required to perform. All necessary parts to provide a
complete and operable circuit breaker installation such as main equipment,
terminals, control parts, connectors and other devices whether specifically called
for herein or not shall be provided. The support structure of circuit breaker as well
as that of control cabinet shall be hot dip galvanised. All other parts shall be
painted as per approved shade.
3.4.5.2
Operating Duty and Performance
a) The circuit breaker shall be rated for the switching, interrupting and current
carrying duty imposed upon them in their intended application.
b) The total interrupting time shall be 2 cycles or less (5 cycles or less in case of 36kV
CB) from energization of trip circuit of the circuit breaker to the extinction of the
arc. The total closing time shall be less than 150 msec from energization of closing
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circuit of the circuit breaker to closing of the breaker contacts. The operating duty
cycle shall be 0 - 0.3 sec - CO - 3 min - CO, with no de-rating for the first reclosure between operations over the voltage range from nominal to rated maximum
voltage and from zero to the maximum rated interrupting current without the
necessity of intermediate maintenance. The circuit breakers shall be capable of
withstanding the transient recovery voltage as per IEC-62271 (values to be
determined by the Contractor).
c) The circuit breaker shall be designed for M2C2 class (M2C1 in case of 36kV CB)
as per IEC 62271 under all duty conditions.
d) The circuit breaker shall meet the duty requirements for any type of fault or fault
location and for line switching when used on a 420kV, 245kV& 145kV effectively
grounded system and perform make and break operations as per the stipulated duty
cycles satisfactorily.
e) The circuit breaker shall be capable of performing their required duty as per
application including
i)
Interrupting steady and transient magnetizing current of transformers of
specified ratings or as the case may be.
ii)
Interrupting line charging current as per IEC.
iii)
Clearing short line faults (Kilometric faults) with source impedance behind
the bus equivalent to symmetrical fault current specified.
iv)
Clearing bus faults on 132kV AC switchyard.
v)
Clearing faults as second-in-line breaker in the event of failure of main
breaker.
vi)
Breaking small inductive currents of 0.5 A to 10 A without switching over
voltage exceeding 2.3 p.u.
vii) Breaking 25% of the rated fault current at twice rated voltage under phase
opposition condition.
viii) Breaking large capacitive currents considering the largest bank/sub-bank of
filters under most onerous condition causing maximum stress to the breaker.
The breakers shall satisfactorily withstand the high stresses imposed on them
during fault clearing, load rejection and re-energization with trapped charges.
The breakers shall also withstand the voltages specified.
f) The total break time as specified shall not be exceeded under any of the following
duties:
i)
Test duties 1,2,3,4,5 (TRV as per IEC:62271-100)
ii)
Short line fault L75, L90 (TRV as per IEC:62271-100)
g) The Bidder may please note that the total break time of the breaker shall not be
exceeded under any duty conditions specified.
3.4.5.3
Constructional Features
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The features and constructional details of the circuit breaker shall be in accordance
with requirements stated hereunder:
a)
The gap between the open contacts shall be such that it can withstand at least the
rated phase to ground voltage for 8 hours at zero gauge pressure of SF6 gas due to
leakage. The breaker should be able to withstand all dielectric stresses imposed on
it in open condition at lockout pressure continuously (i.e. 2 p.u. across the breaker
continuously).
b)
If multi break interrupters are used, these shall be so designed and augmented that
a uniform voltage distribution is developed across them. Calculations/test reports in
support of the same shall be furnished by the Contractor. The thermal and voltage
withstand capabilities of the grading elements shall be adequate for the service
conditions and duty specified.
c)
The SF6 circuit breaker shall meet the following additional requirements :
i)
The circuit breakers shall be of single pressure buffer type. The design and
construction of the circuit breaker shall be such that neither SF6 gas shall
leak to atmosphere and nor moisture shall enter in the breaker. There shall
not be any condensation of SF6 gas on the internal insulating surface of the
circuit breakers.
ii)
All gasket surfaces shall be smooth, straight and reinforced, if necessary, to
minimize distortion and to make a tight seal. The operation rod connecting
the operating mechanism to the arc chamber shall have adequate seals. The
SF6 gas leakage should not exceed 1% per year. In case the leakage under
specified conditions is more than 1% after one year of commissioning of the
circuit breaker, the manufacturer shall have to supply free of cost, the total
make up gas requirement for subsequent ten(10) years based on actual
leakage observed during first year of operation after commissioning. In the
interrupter assembly there shall be an absorbing product box to minimize the
effects of SF6 decomposition products and moisture. The material used in the
construction of the circuit breakers shall be such as to be fully compatible
with SF6 gas as well as its decomposition products.
iii)
Each pole shall form an enclosure filled with SF6 gas independent of two
other poles and the SF6 density of each pole shall be monitored. The SF6 gas
density monitor shall be provided on each of the individual poles.
iv)
The gas density in the SF6 circuit breaker shall never be less than the
minimum required insulating density of SF6. Gas density monitoring
equipment with two level alarms shall be provided.
v)
The dial type SF6 gas density monitor shall be adequately temperature
compensated to model the density changes due to variations in ambient
temperature within the body of the circuit breaker as a whole. The density
monitor shall meet the following requirements:
It shall be possible to dismantle the density monitor for checking/replacement
without draining the SF6 gas by using suitable interlocked non-return valve
coupling.
It shall damp the pressure pulsation while filling the gas so that the flickering
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of the pressure switch contacts does not take place. Filling of SF6 gas shall
not be performed in the closed position of breaker.
vi)
Suitable means for pressure relief shall be provided in the gas chamber of
circuit breaker to avoid the damages or distortion during the occurrence of
abnormal pressure increase or shock waves generated by internal electric
fault arcs. The position of vents, diaphragms and pressure relief devices shall
be so arranged to minimize danger to the operators in the event of gas or
vapour escaping under pressure.
vii) Each circuit breaker shall be capable of with standing a vacuum of 8 mill
bars without distortion or failure of any parts.
viii) Sufficient SF6 gas including that required for gas analysis during filling shall
be provided to fill all the circuit breakers installed. In addition 20% of total
gas requirement shall be supplied at respective station, in separate cylinders
as spare requirement for Employer’s later use.
d)
3.4.5.4
Provision shall be made for attaching an operational analyser after installation at
site to record contact travel, and making measurement of operating timing,
synchronization of contacts in one pole and dynamic contact resistance
measurement.
Sulphur Hexafluoride Gas (SF6 Gas)
a)
The SF6 gas shall comply with IEC-60376, 376A and 376B and shall be suitable in
all respects for use in the switchgear under the operating conditions.
b)
The high pressure cylinders in which the SF6 gas shall be shipped and stored at site
shall comply with requirements of relevant IEC/ British standards and regulations.
c)
SF6 gas shall be tested for purity, dew point, break down voltage, air, hydrolysable
fluorides and water content as per IEC-60376, 376A and 376B and test certificates
shall be furnished to Employer indicating all the tests as per IEC-60376 for each lot
of SF6 gas. Gas bottles shall be tested for leakage after receipt at site.
3.4.5.5
Insulators
a)
The porcelain of the insulators shall conform to the requirements stipulated under
Clause 3.4.11 of this section.
b)
The mechanical characteristics of insulators shall match with the requirements
specified.
c)
All insulators shall conform to IEC-61264(for pressurised hollow column
insulators) and IEC-233(for others). All routine and sample tests shall be
conducted on the hollow column insulators as per these standards with
requirements and procedures modified as under:
i)
Pressure test as a routine test
ii)
Bending load test as a routine test
iii)
Bending load test as a sample test on each lot.
iv)
Burst pressure test as a sample test on each lot.
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v)
d)
In addition to the above, ultrasonic test shall be carried out as additional
routine test.
Jointed porcelain shall not be accepted.
3.4.5.6
Mandatory Maintenance Equipment: deleted
3.4.5.7
Operating Mechanism and Control
General Requirements
a)
Circuit breaker shall be operated by spring charged mechanism, or a combination
of hydraulic and spring mechanism. The 36kV vacuum circuit breakers shall be
operated by motor spring stored energy mechanism only. The mechanism shall be
housed in a weather proof and dust proof control cabinet. Circuit Breakers with
Hydraulic mechanism only is not acceptable.
b)
The operating mechanism shall be strong, rigid, not subject to rebound and shall be
readily accessible for maintenance for a man standing on ground.
c)
The operating mechanism shall be suitable for high speed reclosing and other
duties specified. During re-closing operation the breaker operating mechanism and
control shall have capability to close fully and re-open if required. The mechanism
shall be anti-pumping and trip free (as per IEC definition) under every method of
closing.
d)
The mechanism shall be such that the failure of any auxiliary spring shall not
revent tripping and shall not cause trip or closing operation of the power operating
devices.
e)
A mechanical indicator shall be provided to show open and close position of the
breaker. It shall be located in a position where it shall be visible to a man standing
on the ground level with the mechanism housing closed. An operation counter shall
also be provided in the central control cabinet.
f)
Working parts of the mechanism shall be of corrosion resisting material. Bearings
which require grease shall be equipped with pressure type grease fittings. Bearing
pins, bolts, nuts and other parts shall be adequately pinned or locked to prevent
loosening or changing adjustment with repeated operation of the breaker.
g)
The Contractor shall provide software based condition based monitoring for life
assessment and maintenance of the Circuit Breaker.
Control
a)
The close and trip circuits shall be designed to permit use of momentary contact
switches and push buttons.
b)
Each breaker pole shall be provided with two (2) independent tripping circuits and
coils each being connected to different set of protective relays.
c)
The breaker shall normally be operated by remote electrical control. Electrical
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tripping shall be performed by shunt trip coils. However, provisions shall be made
for local electrical control. For this purpose a local/remote selector switches and
close and trip push buttons shall be provided in the breaker central control cabinet.
d)
The trip coils shall be suitable for trip circuit supervision. During both open and
close position of breaker. The trip circuit supervision relay would be provided.
e)
Closing coil & associated circuits shall operate correctly at all values of voltages
between 85% and 110 % of rated voltage. Shunt trip coil shall operate correctly
under all operating conditions of the circuit breaker up to the rated breaking
capacity of the circuit breaker and at all values of supply voltage between 70% and
110% of rated voltage.
f)
Density meter contacts and pressure switch contacts shall be suitable for direct use
as permissive in closing and tripping circuits. Separate contacts have to be used for
tripping and closing circuits. If contacts are not suitably rated and multiplying
relays/contactors are used for density, monitor and pressure switch contact
multiplication then fail safe logic/schemes shall be employed. DC supplies for all
auxiliary circuits shall be monitored and provision shall be made for remote
annunciation and operation lockout in case of failures. Density monitors are to be
so mounted that the contacts do not change on vibration during operation of circuit
breaker.
g)
The auxiliary switch of the breaker shall be positively driven by the breaker
operating rod.
Spring Operated Mechanism
a)
Spring operated mechanism shall be complete with motor, opening spring and
closing spring with limit switch for automatic charging and other necessary
accessories to make the mechanism a complete operating unit.
b)
As long as power is available to the motor, a continuous sequence of the closing
and opening operations shall be possible. The motor shall have adequate thermal
rating for this duty.
c)
After failure of power supply to the motor OCO operation shall be possible with
the energy contained in the operating mechanism.
d)
Breaker operation shall be independent of the motor which shall be used solely for
compressing the closing spring. Facility for manual charging of the closing spring
shall also be provided. The motor rating shall be such that it requires not more than
30 seconds for full charging of the closing spring.
e)
Closing action of circuit breaker shall compress the opening spring ready for
tripping.
f)
When closing springs are discharged after closing the breaker they shall be
automatically charged for the next operation and an indication of this shall be
provided in the local control cabinet.
g)
Provisions shall be made to prevent a closing operation of the breaker when the
spring is in partial charged condition. Mechanical interlocks shall be provided in
the operating mechanism to prevent discharging of closing springs when the
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breaker is already in the closed position.
h)
3.4.5.8
The spring operating mechanism shall have adequate energy stored in the operating
spring to close and latch the circuit breaker against the rated making current and
also to provide the required energy for the tripping mechanism in case the tripping
energy is derived from the operating mechanism.
Support Structures
a)
The structure design shall be such that during operation of circuit breaker
vibrations are reduced to a minimum.
b)
If required, the Contractor shall provide suitable platform with steps on both sides
of the circuit breaker for easy accessibility for monitoring the density/pressure of
gas.
3.4.5.9
Terminal Pads
The circuit breaker terminal pads shall be made up of high quality electrolytic
copper or aluminium. The terminal pad shall have protective covers which shall be
removed before interconnections.
3.4.5.10 Fittings and Accessories
Following is a partial list of some of the major fittings and accessories to be
furnished by Contractor in the central control cabinet. Number and exact location
of these parts shall be indicated in the drawing.
a)
Cable glands, lugs, ferrules, etc.
b)
Local/Remote changeover Switch
c)
Open/Close buttons and Operation counter
d)
Pressure gauges
e)
Control switches to cut off control power supply
f)
MCBs/MCCBs as required
g)
Anti-pumping relay
h)
DC auxiliary power supervision relay.
i)
Pole discrepancy relay
j)
Rating and diagram plate in accordance with IEC
k)
The number of terminals provided shall be adequate to wire out all contacts and
control circuits after leaving 24 terminals as spare for future use.
3.4.5.11 Tests
Type Tests
Each type of circuit breaker along with its operating mechanism shall conform to
the type tests as per IEC: 62271-100.
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Routine Tests
Routine tests as per IEC: 62271-100 shall be performed on all circuit breakers.
Site Tests
All routine tests except dielectrics shall be repeated on the completely assembled
breaker at site.
3.4.5.12 Technical Parameters
The Contractor shall determine the technical parameters of breakers to be provided.
Refer to Appendix-A3 of Schedule-A of volume 2 of 2 (Schedule of Requirements)
for the technical parameters of the circuit breakers generally used by the Employer
and are given for the information of the Contractor.
3.4.6
Disconnectors and Earth Switches
3.4.6.1
General
a)
The disconnectors (isolators), earth (ground) switches and accessories shall
conform in general to IEC-62271-102 except to the extent explicitly modified in
the Specification.
b)
The isolators shall be mechanically ganged only. Earth switch(es) shall be provided
on isolators wherever possible, otherwise free standing earth switch shall be
provided.
c)
Complete isolator with all the necessary items for successful operation shall be
supplied including, but not limited to, one central (common) control cabinet for
each 3 phase isolator/earth switch with all the required electrical devices mounted
therein, complete with base frame, linkages, complete operating mechanism etc.
3.4.6.2
Operating Duty and Performance
a)
Isolators and earth switches shall be capable of withstanding the dynamic and
thermal effects of the maximum possible short circuit current of the systems in
their closed position. They shall be constructed such that they do not open under
influence of short circuit current.
b)
The earth switch shall be capable of discharging trapped charges.
c)
The isolators shall be capable of making/breaking normal currents when no
significant change in voltage occurs across the terminals of each pole of isolator on
account of make/break operation.
d)
The isolator shall be capable of making/breaking magnetizing current of at least
0.7A at 0.15 power factor and capacitive current of at least 0.7A at 0.15 power
factor.
e)
The terminals of the isolator and earth switch(es) shall be able to withstand the
total forces including wind loading and electrodynamics forces on the attached
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conductor without impairing reliability or current carrying capacity in accordance
with IEC-62271-102.
f)
3.4.6.3
The earth switch should be able to carry the same fault current as the main blades
of the isolator and shall withstand dynamic stresses.
Constructional Features
The main features and constructional details of isolators with earth switches and
other accessories shall be in accordance with requirements stated hereunder:
General
Design of the isolator shall be such as to permit addition of earth switches at a
future date. It shall be possible to interchange position of earth switch to either side
of pole even at site.
Contacts
a)
The isolator shall be provided with high pressure current carrying contacts made of
copper on the hinge and jaw ends and all contact surfaces shall be silver plated.
The thickness of silver plating shall not be less than 25 microns. The contacts shall
be accurately machined and self aligned.
b)
The contacts shall be of sufficient pressure to ensure effective contact and low
contact resistance throughout the life of the switch. The contact pressure shall not
exceed a safe working value for the materials in contact and shall cause no
abrasion or scarring of the contacts.
c)
The contacts shall be of self-aligning and self- cleaning type and shall be so
designed that binding can not occur after remaining closed for prolonged periods.
d)
No undue wear or scuffing shall be evident during the mechanical endurance tests.
Contacts and springs shall be designed so that readjustments in contact pressure
shall not be necessary throughout the life of the isolator/earth switch. Each contact
or pair of contacts shall be independently sprung so that full pressure is maintained
on all contacts at all times. Provision shall be made to adjust the contact pressure.
e)
Contact springs shall not carry any current and shall not loose their characteristics
due to heating effects.
f)
The isolator shall be so designed that when operated within their specified rating,
the temperature of each part shall be limited to values consistent with a long life for
the material used. The temperatures shall not exceed the permissible limits given in
IEC-62271-102 under specified ambient conditions.
Base
a)
Each single pole of the isolator/earth switch shall be provided with a completely
galvanized steel base. The base shall be rigid and self supporting and shall require
no guying or cross bracing between phases.
b)
The frame of each isolator and earthing switch shall be provided with two ground
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terminals for connection to the ground mat.
Blades
a)
All metal parts shall be of non-rusting and non corroding material. All current
carrying parts shall be made from high conductivity electrolytic copper/aluminium.
Bolts, screws and pins shall be provided with lock washers. Keys or equivalent
locking facilities when provided on current carrying parts shall be made of copper
silicon alloy or equivalent. The bolts or pins used in current carrying parts shall be
made of nonferrous and non- corroding material. All castings except current
carrying parts shall be made of malleable cast iron or cast-steel. No grey iron shall
be used in the manufacture of any part of the isolator.
b)
The live parts shall be designed to eliminate sharp joints, edges and other corona
producing surfaces. Where this is impracticable adequate corona shields shall be
provided. Corona shields/rings etc. shall be made up of aluminium/aluminium
alloy.
c)
The isolator/earth switch shall be so constructed that the switch blade shall be
locked in the open/close position and shall not fall to the closed/opened position in
case the operating shaft gets disconnected.
d)
The isolator/earth switch including their operating parts shall be such that they
cannot be dislodged from their open or closed positions by short circuit forces,
gravity, wind pressure, vibrations, shocks, or accidental touching of the connecting
rods of the operating mechanism.
e)
The isolator/earth switch shall be designed such that no lubrication of any part is
required except at very infrequent intervals.
f)
The switch blade contact shall enter into the counter contact even if it is misaligned
by 45 mm in any direction.
Insulator
a)
The insulator shall conform to IEC-60168. The porcelain of the insulator shall have
minimum cantilever strength of 800kg. The insulators shall be of solid core type.
b)
Pressure due to the contact shall not be transferred to the insulators after the main
blades are fully closed.
c)
The insulators shall be so arranged that leakage current shall pass to earth and not
between terminals of same pole or between phases.
Earth Switches
a)
Wherever earth switch(es) are specified these shall include the complete operating
mechanism and auxiliary contacts.
b)
The earth switch shall form an integral part of the isolator and shall be mounted on
the base frame of the isolator, whenever possible.
c)
The earth switch shall be manual operated.
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d)
The earth switch(es) shall be constructionally interlocked, wherever provided with
the isolator, so that the earth switch(es) can be operated only when the isolator is
open and vice versa. The constructional interlocks shall be a built in feature in
construction of isolator and shall be in addition to the electrical and mechanical
interlock provided in the operating mechanism.
e)
In addition to the constructional interlock, isolator and earth switch(es) shall have
provision to prevent their electrical and manual operation unless the interlocking
conditions are met. All these interlocks shall be of fail-safe type. Suitable
individual interlocking coil arrangements shall be provided. The interlocking coil
shall be suitable for continuous operation from dc supply and within a variation
range as stipulated.
f)
Each earth switch shall be provided with flexible copper/aluminium braids for
connection to earth terminal. These braids shall have the same short time current
carrying capacity as the earth blade. The transfer of fault current through switch
connection shall not be accepted.
g)
The plane of movement and final position of the earth blades shall be such that
adequate electrical clearances are obtained from adjacent live parts including in the
course of its movement between Close and Open position.
Operating Mechanism
a)
145kV Isolators shall be ac motor operated, 36kV isolator and earth switches shall
be manual operated.
b)
Limit switch for control shall be fitted on the isolator/earth switch shaft, within the
cabinet to sense and ensure the open and close positions of the isolator and earth
switch.
c)
After final adjustment has been made it shall not be possible for any part of the
mechanism to be displaced at any point in the travel sufficient enough to allow
improper functioning of the isolator/earth switch whenever it is opened or closed at
any speed. All holes in cranks, linkage etc. having moving pins shall be drilled to
accurately fit so as to maintain the minimum of slack and loose motion in the entire
mechanism.
d)
A "Local/Remote” selector switch and a set of "Open/Close" push buttons shall be
provided in the control cabinet of the isolator to permit its operation. A
“Local/Remote" selector switch and "Open/Close" push buttons shall also be
provided in central control cabinet to permit simultaneous operation of all three
phase.
e)
Provision shall be made in the control cabinet to disconnect power supply to
prevent local/remote power operation.
f)
Suitable reduction gearing shall be provided between the motor and the drive shaft
of the isolator. The mechanism shall stop rapidly when motor supplies are switched
off.
g)
Each motor operated mechanism shall be subjected to blocked rotor test.
3.4.6.4
Operation
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a)
The isolator and earth switch shall have individual drives for main blades. The
operating mechanism of the three poles shall be well synchronized and interlocked.
b)
The design shall be such as to provide maximum reliability under all service
conditions. All operating linkages carrying mechanical loads shall be designed for
negligible deflection. The length of operating rods shall be capable of adjustments,
by means of screw thread which can be locked with a lock nut after an adjustment
has been made. The isolator & earth switches shall be provided with "over centre"
device in the operating mechanism to prevent accidental opening by wind or
vibration or short circuit forces or movement of the support structures.
c)
Each isolator and earth switch shall be provided with a manual operating handle
enabling one man to open or close the isolator or earth switch with ease in one
movement while standing at ground level. The manual operating handle shall have
provision for padlocking. The operating handle shall be located at 1000 mm from
the base of isolator support structure.
d)
The isolator/earth switch shall be provided with positive continuous control
throughout the entire cycle of operation. The operating rods shall be sufficiently
rigid to maintain positive control under the most adverse conditions and when
operated in tension or compression for closing. They shall also be capable of
withstanding all torsional and bending stresses due to operation of the isolator/earth
switch. Wherever supported the operating rods shall be provided with bearings on
either ends. The operating rods shall be provided with suitable universal couplings
to account for any angular misalignment.
e)
The transmission of motion from the electrical operating mechanism shall be by
rigid members. It is required that, in the event of over torque of the switch
mechanism, no part of the main switch mechanism shall bend, twist or shear and so
allow the auxiliary switch contacts to operate erroneously.
f)
All rotating parts shall be provided with grease packed roller or ball bearings in
sealed housings designed to prevent the ingress of moisture, dirt or other foreign
matter. Bearings pressure shall be kept low to ensure long life and ease of
operation. Locking pins wherever used shall be rustproof.
g)
The position of movable contact system (main blades) of each of the isolators and
earth switches shall be indicated by a mechanical indicator at the lower end of the
vertical rod of shaft for the isolators and earth switch. The indicator shall be of
metal and shall be visible from operating level.
h)
Signalling of closed position shall not take place unless it is certain that the
movable contacts shall reach a position in which rated normal current, peak
withstand current and short time withstand current can be carried safely. Signalling
of open position shall not take place unless movable contacts have reached a
position such that clearance between contacts is at least 80% of the isolating
distance.
i)
Counter balance spring if required shall be provided for counter balancing the
isolator and earth switch to prevent impact at the end of the travel both on opening
and closing. The spring shall be made of non rusting type alloy.
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3.4.6.5
Tests
Each type of isolator and earth switch alongwith their operating mechanism shall
be subjected to the type tests and routine tests in accordance with IEC-62271-102.
The radio interference voltage and corona extinction voltage test shall also be
conducted as type test.
3.4.6.6
Technical Parameters
The Contractor shall determine the technical parameters of the isolators/earth
switches. Refer to Appendix-A3 of Schedule-A of volume 2 of 2 (Schedule of
Requirements) for the technical parameters of the isolators/Earthing switch
generally used by the Employer and are given for the information of the Contractor
3.4.7
Instrument Transformers
3.4.7.1
General
The AC Instrument Transformers and accessories shall conform to the latest
version of IEC 60044. The instrument transformers provided for control, metering
and protective relaying functions shall have accuracy ratings and burden
capabilities adequate to provide their designated functions within the overall
accuracy requirements of the systems.
3.4.7.2
Technical and Constructional Requirements
The following requirements shall apply:
3.4.7.2.1 Common for all Instrument Transformers
Bushing Insulators
a)
The instrument transformers shall be oil filled with porcelain/silicone rubber
housing bushings suitable for outdoor service and upright mounting on steel
structures.
b)
Bushing/Insulators shall conform to requirements of Clause 3.4.11.
c)
Bushings shall be provided with oil filling and drain plugs, oil sight glass for CT
and for electromagnetic unit of CVT etc.
d)
Instrument transformers shall be hermetically sealed units. The Bidder/Contractor
shall furnish details of the arrangements made for the sealing of instrument
transformers.
e)
Polarity shall be marked on each instrument transformer and at the lead terminals
at the associated terminal block.
Box
Each single phase instrument transformers shall be complete with its terminal box.
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The terminal box shall meet the requirements of IP 55 relevant IECStandard. A
marshalling box for a set of 3 instrument transformers shall be provided, wherever
required.
Tank
The Instrument transformer tank alongwith top metallics shall be hot dip
galvanised or painted.
Lifting Arrangements
Instrument transformer shall be provided with suitable lifting arrangement, to lift
the entire unit. The lifting arrangement shall be clearly shown in the general
arrangement drawing.
3.4.7.2.2 Current Transformers (CT)
a)
Current transformers shall have single primary either ring type, or bar type (live
tank) , or hair pin type (dead tank) and suitably designed for bringing out the
secondary terminals in a weather proof terminal box at the bottom. These
secondary terminals shall be terminated to stud type non disconnecting terminal
blocks inside the terminal box.
b)
Different ratios, as specified/required shall be achieved by secondary taps only and
primary reconnection shall not be acceptable.
c)
Core lamination shall be of cold rolled grain oriented silicon steel or other
equivalent alloys.
d)
The expansion chamber at the top of the insulators shall be suitable for expansion
of oil.
e)
Facilities shall be provided at terminal blocks for star/delta formation, short
circuiting and grounding of CT secondary terminals.
f)
The guaranteed burdens and accuracy class are to be simultaneous for all cores.
The accuracy class for measuring cores shall be met upto the rated extended
primary current.
g)
The rated extended primary current of the CT's shall be 120% of rated primary on
all except (one) highest tap ratio.
h)
The current transformer shall be suitable for horizontal transportation.
i)
The instrument security factor of metering core at all ratios shall be less than 5. If
any auxiliary CTs/reactor are used in the current transformers than all parameters
specified/required shall have to be met treating auxiliary CTs as an integral part of
the current transformer. The auxiliary CTs/reactor shall preferably be inbuilt
construction of the CT. In case these are to be mounted separately these shall be
mounted in the central marshalling box suitably wired up to the terminal blocks.
j)
The current transformers shall be suitable for high speed auto-re-closing, if
required.
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k)
Special Technical Requirements
i)
Through Fault Capability The current transformers shall be capable of
withstanding with the secondary short circuited, a fully offset primary current
having an ac (i.e. symmetrical) component with an rms value equal to the
specified short-circuit capacity of the system. The CT’s shall withstand the
discharges of filter banks after ground fault.
ii)
Transient Performance (If applicable) The current transformers shall meet the
requirements for transient performance and tests shall be conducted
accordingly.
3.4.7.2.3 Voltage Transformers
a)
Voltage transformers shall be Inductive Type.
b)
Each core of secondary winding to be used for protection purpose shall be
protected by MCB’s of suitable rating. NO and NC contacts shall be provided on
the MCB for monitoring purposes. The secondary terminals of the IVT’s shall be
terminated to the stud type non-disconnecting terminal blocks in the individual
phase secondary boxes via the MCB’s.
c)
The accuracy of metering winding shall be maintained through out the entire
burden range upto total burden simultaneously on all the three windings without
any adjustments during operation.
d)
It shall be ensured that access to secondary terminals is without any danger of
access to high voltage circuit.
e)
A protective surge arrester shall be provided to prevent breakdown of insulation by
incoming surges and to limit abnormal rise of terminal voltage of shunt capacitor,
tuning reactor/RF choke etc. due to short circuit in transformer secondaries.
f)
Special Technical Requirements
i)
Transient Response
The transient response (at rated frequency and beyond) shall be such that ,
after sudden removal of the primary voltage, the transient secondary voltage
in the voltage transformer shall not exceed 10 (Ten) percent of the peak
value of the secondary voltage existing before the collapse of the primary
voltage to zero nor it shall exceed value required to meet the performance.
This value shall be measured (oscillograms) following the primary short
circuit when the capacitor voltage transformer is loaded with 25% and 100%
of rated burden at 0.8 power factor lagging.
ii)
Ferro-resonance
The Ferro-resonance requirement shall be met as per the relevant standards.
iii)
Protective Device
A protective device shall be incorporated in the voltage transformer for the
purpose of limiting over voltages which may appear across one or more of its
components. The device shall include a heavy duty class spark gap with
adjustable setting and drain coil. The setting of the protective device shall be
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determined by the Contractor, however, it shall be adjustable and shall not
introduce distortion in the secondary voltage wave shape at rated frequency
and at an applied voltage up to 1.2 per unit of nominal voltage. Should the
protective device operate on switch surge or atmospheric over voltages, the
secondary voltage shall recover to its correct wave shape within 4 ms when
the applied voltage is 1.2 per unit of nominal voltage.
iv)
Power Line Carrier
Coupling Application If required, the capacitor voltage transformers shall be
equipped with power line carrier coupling components, and the capacitance
value shall be that required for PLCC coupling purposes.
v)
Reproduction of Harmonics
Harmonics with frequency 100 Hz to 650 Hz superimposed on the
fundamental frequency shall be reproduced within an accuracy of amplitude
error of 10% & phase angle error (for each separate harmonic) of 10 degree
elect.
vi)
Reproduction of Transients
A step of 10% of rated voltage (rms) superimposed on the primary voltage
shall be reproduced at maximum burden with a delay (time constant) of less
than 100 microsecond and within +10% of correct value within 400
microsecond.
3.4.7.3
Type Tests
The current transformers shall be type tested as per the requirements of IEC:
60044-1 and the voltage transformers shall be type tested as per IEC-60044-5.
3.4.7.4
Routine Tests
The current transformers shall be subject to routine tests as per IEC: 60044-1 and
the voltage transformers shall be routine tested as per IEC- 60044-5. Additional
routine tests as specified below shall also be conducted on each unit:
Current Transformers
a)
Measurement of capacitance
b)
Measurement of tan delta at 0.3, 0.7, 1.0 and 1.1 Um/[3
c)
Oil leakage test
Voltage Transformers
a)
Capacitance and loss angle measurement before and after dielectric tests as per IEC
b)
Sealing test as per IEC
3.4.7.5
Technical Parameters
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The technical parameters shall be determined by the Contractor. Refer to
Appendix-A3 of Schedule-A of volume 2 of 2 (Schedule of Requirements) for the
technical parameters for Instrument Transformers generally used by the Employer
and are furnished for the information of the Contractor.
3.4.8
Surge Arresters
3.4.8.1
General
Surge arresters shall be of the type employing non-linear metal oxide resistors
without spark gaps. The Contractor shall demonstrate by calculations that the surge
arresters will adequately protect the switchgear arrangement proposed.
3.4.8.2
Operating Duty and Performance
The protective characteristics and discharge duties shall be determined by the
Contractor. The arresters shall give consistent protection to their associated
equipment against over voltages produced by lightning, switching, station internal
or external faults, and other system disturbances.
The arresters shall be rated and tested such that they are able to discharge a
specified maximum energy due to the application of temporary voltages of form
and magnitude which can occur in service as determined by insulation coordination
studies to be carried out by the Contractor, without coming into the temperature
region where thermal runaway could result upon subsequent application of
maximum transient and steady state voltage conditions.
Particular attention shall be given to the high discharge currents which some of the
arresters may experience in service due to the requirements to discharge the energy
of the, shunt capacitors and reactive compensating equipment or in other
circumstances.
The design of the arresters shall take into account and shall maximize the degree of
current sharing between complete arresters. Similarly the design shall also take into
account and shall maximize the degree of current sharing between parallel columns
of the same arrester.
The reference current of the arresters shall be high enough to eliminate the
influence of grading and stray capacitance on the measured reference voltage. The
Bidder/Contractor shall furnish the values and supporting calculations along with
the Bid. The arresters shall be fully stable thermally under site conditions and shall
take care of the effect of direct solar radiation.
3.4.8.3
Constructional Features
Surge arresters shall be housed in porcelain insulators designed to withstand
extremes of the environment described. The insulation shall have a minimum
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creepage distance of 25 mm/kV rated system phase to phase voltage. The method
of sealing against the ingress of moisture shall be of a type well proven in service
and the manufacturing procedures shall include an effective leak test which can be
demonstrated to the inspecting engineer if required.
The internal components of arresters shall be arranged to minimize radial voltage
stresses, internal corona and to ensure minimal capacitive coupling with any
conducting layer of pollutant on the outside of the porcelain housing. Except where
approved, organic materials are not permitted.
Good electrical contact shall be maintained between resistor blocks taking account
of any thermal expansion and contraction of the block or mechanical shock during
transport and erection, by installing a well proven clamping system.
Metal oxide arresters installed outdoors shall be able to dissipate, when new, twice
the energy generated in the resistor blocks when energized at their maximum
continuous operating voltage immediately having been subjected to the discharge
duties specified in IEC 60099-4 and assuming that the porcelain housing and the
surrounding air is at least 5˚C higher than the maximum ambient air temperature
specified.
Good quality control of the manufacturing process of the resistors shall be ensured
by rigorous testing procedures. The procedures shall ensure that the characteristics
of the blocks are, and will remain, within the specified limits when new and
throughout the anticipated life of the arresters. Samples may be selected at random
by the Engineer for special tests to be agreed with the manufacturer.
All surge arresters shall be fitted with a pressure relief diaphragm which shall
prevent explosive shattering of the porcelain housing in the event of an arrester
failure and the arrester shall have been tested according to the high and low current
tests specified in IEC 60099-1.
3.4.8.4
Fittings and Accessories
Arresters shall be supplied complete for installation in an outdoor switchyard,
including insulating bases and surge counters, one per phase, and, if applicable,
grading rings. The material used for terminals shall be compatible with that of the
conductors to which they are to be connected.
Each arrester shall be identified by a rating plate in accordance with the
requirements of IEC 60099-4. In addition an identification mark shall be
permanently inscribed on each separately housed unit of a multi-unit arrester so
that units can be replaced in the correct position in the event of them being
dismantled.
Surge counters shall have an internal assembly which is matched to the line
discharge capability of the arrester and shall include a leakage current meter with a
bi-linear scale for ease of reading. Auxiliary contacts are to be provided to signal
remote indication of counter operation.
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3.4.8.5
Tests
Arresters shall be designed and tested in accordance with the requirements of IEC
60099-4. Any departure shall be the subject of agreement between the Engineer
and the Contractor. Routine tests shall be carried out in accordance with the
requirements of Section 15 of this Specification.
3.4.8.6
Technical Parameters
The technical parameters shall be determined by the Contractor. Refer to
Appendix-A3 of Schedule-A of volume 2 of 2 (Schedule of Requirements) for the
technical parameters for surge arrestor generally used by the Employer and are
furnished for the information of the Contractor.
3.4.9
Neutral Grounding Resistors
The earthing resistors shall be of the metal grid type with enclosure having degree
of protection IP 33 and suitable for outdoor service on the neutral earthing system
as specified. The framework and enclosure shall be of galvanised steel. The grids
shall be adequately supported on steel rods and porcelain insulators and be
designed to withstand the currents flowing under fault conditions. Adequate
insulating barriers shall be provided to prevent internal flashover.
The resistor shall be complete with lifting and jacking lugs, access panels, holding
down bolts or clamps, earth terminals, connectors and connections.
The bushing shall have a minimum creepage distance of 25mm/kV of rated system
phase to neutral voltage.
The specified resistance shall be that at the design ambient temperature and it shall
be capable of passing the specified current for 10 seconds with a maximum
temperature rise as stated in the Schedule of Guarantees.
3.4.10
Busbars, Conductors and Connections
Busbars and electrical connections in outdoor substations shall be in accordance
with BS 215, 159 and 2898 and relevant IEC standards in respect of current rating
and material analysis.
Overhead conductors carried by the switchyard structures shall be erected with
such sags and tensions that when the conductors are subjected to the load
combinations in Section 11, the factor of safety will not be less than 3.5.
Materials used for busbars and connections shall be stressed to not more than
two-fifths of their elastic limit. Provision shall be made for expansion and
contraction with variation in conductor temperature and busbars shall be arranged
so they may be readily extended in length with a minimum of disturbance to
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existing equipment.
3.4.10.1 Tubular Bus Conductors
General
Aluminium used shall be of grade 63401 WP conforming to relevant IEC/BS
Standard.
Constructional Features
a)
For outside diameter (OD) & thickness of the tube there shall be no minus
tolerance. The other requirements shall be as per IEC 114.
b)
Corona bells shall be provided wherever the bus extends beyond the clamps and on
free ends for sealing the ends of the tubular conductor against rain and moisture
and to reduce the electrostatic discharge loss at the end points. There shall be small
drain hole at the end of each corona bell.
c)
The welds in the aluminium tubes shall be kept to the minimum and there shall not
be more than one weld per span. The procedure and details of welding shall be
furnished for approval of the Employer. Material for welding sleeve shall be same
as the Aluminium tube.
Parameters
The size and other parameters of tubular bus conductors suitable for the busbar
specification stated in Appendix A in Volume 3 of the bid document shall be
determined by the Contractor.
Tests
The tests shall be conducted on tubular bus conductors as per relevant IEC
Standard. Also the wall thickness and ovality of the tube shall be measured by
ultrasonic method. In addition to the above tests, 0.2% proof test on both parent
metal and aluminium to be after welding shall be conducted.
3.4.10.2 Flexible Bus-Bars and Earthwire
General
The conductors shall conform to relevant IEC/BS Standard. The number and
diameters of the individual wires forming the finished conductor shall be subject to
approval of Engineer.
Constructional Features
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a)
Workmanship
All the aluminium strands shall be smooth, uniform and free from all
imperfections, such as spills and splits, die marks, scratches, abrasions and kinks
after drawing and also after stranding. The finished conductor shall have a smooth
surface without any surface cuts, abrasions, scuff marks and shall be free from dirt,
grit etc.
b)
Joints in Wires
No joints shall be permitted in the individual wires in the outermost layer of the
finished conductor. However, joints in the inner layers of the conductor shall be
allowed but these joints shall be made by cold pressure butt-welding and shall be
such that no two such joints are within 15 metres of each other in the complete
stranded conductor.
c)
Materials
The aluminium strands shall be hard drawn from electrolytic aluminium rods
having purity not less than 99.5% and a copper content not exceeds 0.04%.
Parameters
The size, rating, number of conductors per phase and the configuration, etc. shall
be determined by the Contractor.
Tests
The following type, acceptance and routine tests and tests during manufacture shall
be carried out on the conductor in addition to the tests specified in relevant
applicable standards.
a)
Type Test
DC Resistance Test on Stranded Conductor On a conductor sample of minimum 5
m length two contact clamps shall be fixed with a predetermined bolt torque. The
resistance shall be measured by Kelvin double bridge by placing the clamps
initially zero meter and subsequently one meter apart. The test shall be repeated at
least five times and the average value recorded. The value obtained shall be
corrected to the value at 20 0C as per relevant IEC Standard.
b)
Acceptance Test
i)
Visual and Dimensions check on Drums
ii)
Visual Check for Joints, Scratches etc.
iii)
Dimensional check on Aluminium Strands
iv)
Check for lay-ratios of various Layers The following tests shall be conducted
once on sample/samples of conductor.
- Breaking load test on aluminium strands
- Wrap load test on aluminium strands
- DC resistance tests on aluminium strands
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All the above tests shall be carried out on aluminium strands after stranding only.
c)
d)
Routine Tests
i)
Check to ensure that the joints are as per specification.
ii)
Check that there are no cuts, fins, etc. on the strands.
iii)
Check that drums are as per specification.
iv)
All acceptance tests as mentioned above are to be carried out on each coil
Tests During Manufacture
Chemical Analysis of Aluminium used for making aluminium strands Samples
taken
from
the
aluminium
ingots/coils/
strands
shall
be
chemically/spectrographically analyzed. The same shall be in conformity to the
specified requirements.
e)
Packing
The conductor shall be supplied in strong wooden drums constructed to protect the
conductor against all damage and displacement during transit, storage and
subsequent handling and stringing operations in the field. The drums shall
generally conform relevant IEC/Standard. Only one length of conductor shall be
wound on each drum.
3.4.10.3 Clamps & Connectors
General
a)
Conductor clamps shall be compression type except for shield wire in accordance
with BS 3288 and shall be made of materials listed below :
For connecting ACSR conductors: Aluminium alloy casting
For connecting equipment terminals made of copper with ACSR conductors:
Bimetallic connectors made from aluminium alloy casting with 2mm thick
Bimetallic liner
For connecting G.I. Shield wire : Galvanised mild steel
Bolts, nuts & Plain washers: Electro galvanised for sizes below M12, for others hot
dip galvanised
Spring washers: Electro-galvanised mild steel suitable
b)
Equipment shall be supplied with the necessary terminals and connectors, as
required by the ultimate design for the particular installation. The conductor
terminations of equipment shall be either expansion, sliding or rigid type. The
requirements regarding external corona and RIV as specified for any equipment
shall include its terminal fittings and the equipment shall be factory tested with the
connectors in position. In case the connector is not available then equivalent
connector may be used. If corona rings are required to meet these requirements
they shall be considered as part of that equipment and included under this scope of
Work.
c)
Where copper to aluminium connections are required, bi-metallic clamps shall be
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used, which have been properly designed to ensure that any deterioration of the
connection is kept to a minimum and restricted to parts which are not current
carrying or subjected to stress. The design details of joint shall be furnished to the
Employer.
d)
Low voltage connectors, grounding connectors and accessories for grounding all
equipment as specified are also included in the scope of Work.
e)
No current carrying part of any clamp shall be less than 10 mm thick. All ferrous
parts shall be hot dip galvanised. Copper alloy liner of minimum 2mm thickness
shall be cast integral with aluminium body for Bi-metallic clamps. When copper
alloy is not cast integral with aluminium body, a bimetallic washer or strip shall be
used to meet the functional requirement.
f)
All casting shall be free from blow holes, surface blisters, cracks and cavities. All
sharp edges and corners shall be blurred and rounded off.
g)
Flexible connectors, braids or laminated straps made for the terminal clamps for
bus posts shall be suitable for both expansion or through (fixed/sliding) type
connection of IPS Aluminium tube as required. In both the cases the clamp height
(top of the mounting pad to centre line of the tube) should be same.
h)
Clamp shall be designed to carry the same current as the conductor and the
temperature rise shall be equal or less than that of the conductor at the specified
ambient temperature. The rated current for which the clamp/connector is designed
with respect to the specified reference ambient temperature, shall also be indelibly
marked on each component of the clamp/connector, except on the hardware.
i)
All current carrying parts shall be designed and manufactured to have minimum
contact resistance.
Constructional Feature
All casting shall be free from blow holes, surface blisters, cracks and cavities. All
sharp edges and corners shall be blurred and rounded off. Size of the
terminal/connector for which the clamp/ connector is suitable shall be
embossed/punched (i.e. indelibly marked) on each components of the
clamp/connector, except on the hardware. The clamp shall be designed to carry the
same current as the conductor and the temperature rise shall be equal or less than
that of the conductor at the specified ambient temperature. The rated current for
which the clamp/ connector is designed with respect to the specified reference
ambient temperature, shall also be indelibly marked on each component of the
clamp/connector, except on the hardware. All current carrying parts shall be
designed and manufactured to have minimum contact resistance. The Corona
extinction voltage for 400 kV and 230 kV class clamps shall not be less than 320
kV and 156 kV respectively.
Tests
The clamps and connectors shall be subject to type and routine tests as per relevant
IEC Standard. Type tests as per IEC Standard shall be carried out on one sample of
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each type and design. One sample of each type and design shall also be type tested
for:
a)
Temperature rise test
b)
Short time current test
c)
Dry corona and RIV test
d)
Resistance test and tensile test
3.4.10.4 Spacers
General
The spacers shall conform to relevant IEC/ BS Standard.
Constructional Features
No magnetic material should be used in the fabrication of the spacers except for the
GI bolts and nuts. Spacer design shall be made to take care of fixing and removing
during installation and maintenance. The design of spacer shall be such that the
conductor does not come in contact with any sharp edge.
Tests
The spacers shall be subjected to the type tests, acceptance tests and routine tests in
accordance with relevant IEC/BS Standard.
3.4.11
Insulators, Bushings, Buses and Hardware
3.4.11.1 Bushings and Support Insulators
General
Bushings shall be manufactured and tested in accordance with IEC-60137 while
hollow column insulators shall be manufactured and tested in accordance with
IEC-60233. The support insulators shall be manufactured and tested as per IEC60168, IEC-60273. The insulators shall also conform to IEC-60815 as applicable.
All bushings shall be one piece only and no joints shall be accepted.
Constructional Features
a)
Porcelain used shall be homogeneous and free from imperfections that might affect
the mechanical or dielectric quality.
b)
Glazing of the porcelain shall be of uniform brown colour, free from blisters, burns
and other similar defects. The ground surface shall not be glazed.
c)
Condenser type bushing shall be provided with :
i)
Oil level gauge.
ii)
Oil filling plug and drain valve if not hermetically sealed.
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iii)
Tap for capacitance and tan delta test.
d)
When bushings have an under-oil end of re-entrant form, the pull through lead
shall be fitted with a gas bubble deflector.
e)
Where current transformers are specified, the bushings shall be removable without
disturbing the current transformers.
f)
Bushings of identical rating shall be interchangeable.
g)
No arching horns shall be provided on the bushings.
h)
All ferrous parts shall be hot dip galvanized or zinc plated and passivated. All
joints shall be air tight. Insulator/bushing design shall be such as to ensure a
uniform compressive pressure on the joints.
i)
Support insulators/bushings/hollow column insulators shall be designed to have
ample insulation, mechanical strength and rigidity for the conditions under which
they shall be used.
j)
When operating at rated voltage there shall be no electric discharge between
conductor and insulators which would cause damage to conductors or insulators by
the formation of substances produced by chemical action. No radio interference
shall be caused when operating at rated voltage.
k)
The design of the insulator shall be such that stresses due to expansion and
contraction in any part of the insulator shall not lead to deterioration.
l)
The Bidder/Contractor shall define the type of insulator (type A or B) as per IEC60168.
m)
Bushing porcelain shall be robust and capable of withstanding the internal
pressures likely to occur in service. The design and location of clamps and the
shape and the strength of the porcelain flange securing the bushing to the tank shall
be such that there is no risk of fracture. All portions of the assembled porcelain
enclosures and supports other than gaskets, which may in any way be exposed to
the atmosphere shall be composed of completely non hygroscopic material such as
metal or glazed porcelain.
n)
Special precaution shall be taken to exclude moisture from paper insulation during
manufacture, assembly, transport and erection. The surface of all paper insulation
shall be finished with non-hygroscopic varnish which can not be damaged easily.
o)
Each porcelain insulator shall have marked upon it the manufacturer's name or
identification mark and year of manufacture. These marks shall be clearly legible
after assembly of fittings and shall be imprinted before firing, not impressed. Each
complete bushing shall be marked with the manufacturer's name or identification
mark, year of manufacture, serial number, electrical and mechanical characteristics
in accordance with IEC 60137:1973.
Parameters
The parameters shall be determined by the Contractor, however the minimum
performance parameters for the 132kV class post insulator shall be as per the
stipulation of Schedule-A of Volume 2 of 2(Schedule of Requirements).
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/31
Tests
Each type of bushing and insulator shall be subjected to type and routine tests in
accordance with applicable standards and acceptance test shall include one minute
dry power frequency withstand test and ultrasonic test (except for hollow
insulator). The ultra sonic test shall be done on the porcelain before assembly. All
sample tests and special tests shall also be conducted.
3.4.11.2 String Insulators & Hardware
General
The insulators for suspension and tension strings shall conform to relevant
IEC/Standard. Insulator hardware shall conform to relevant IEC/Standard. The
insulation levels shall be determined by the Contractor but the minimum
performance characteristics shall be as specified in Schedule A of Volume 2 of 2.
Constructional Features
a)
Requirements specified in Clause 3.4.11.1 above shall also be applicable equally to
string (disc) insulators.
b)
Suspension and tension insulators shall be wet process porcelain with ball and
socket connections. Insulators shall be interchangeable and shall be suitable for
forming either suspension or tension strings. Each insulator shall have rated
strength markings on porcelain printed and applied before firing.
c)
Insulator hardware shall be uniform to the requirements stipulated for clamps and
connectors under Clause 3.4.10.3.
d)
Insulator hardware shall be of forged steel. Malleable cast iron shall not be
accepted except for insulator disc cap. The surface of hardware must be clean,
smooth, without cuts, abrasion or projections. No part shall be subjected to
excessive localized pressure. The metal parts shall not produce any noise
generating corona under operating condition.
e)
Insulator hardware assembly shall be designed as per the design requirement but
for at least 4000 Kg. tensile load per phase for the switchyard with a factor of
safety two (2). Similarly ground wire tension clamp shall be designed for at least
3500 kg tensile load with a factor of safety of two (2).
f)
Tension string assembly shall be supplied along with suitable turn buckle (one turn
buckle per string).
g)
All hardware shall be bolted type.
h)
As an alternative to disc insulator string, the Bidder/Contractor can provide a
combination of long rod insulators, with suitable hardware. This combination shall
be suitable for application specified and should offer the same equivalent
parameters as would be available from the insulator string composed of specified
disc insulators and hardware combination. Further the complete long rod insulator
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/32
string shall be subject to the specified tests and the insulator shall also be subject to
all tests as per relevant standards. All other constructional features specified above
shall also apply to the long rod insulator string.
Parameters
The minimum parameters of insulator discs/complete insulator strings shall be as
per the stipulation of Schedule-A of Volume 2 of 2(Schedule of Requirements).
Tests
The insulators for suspension and tension strings and hardware shall be subjected
to the following type tests, acceptance tests and routine tests.
a)
b)
Type Tests on Insulator Strings:
i)
Dry and Wet Power Frequency Voltage withstand test with corona control
rings and arcing horns
ii)
Dry and Wet Switching surge voltage withstand test with corona control
Ring
iii)
Dry and Wet Impulse Voltage Withstand test with corona control rings
iv)
Voltage distribution test
v)
Corona and RIV test (Dry Condition)
vi)
Mechanical strength test
Type Tests on Disc Insulators:
i)
Thermal and Mechanical performance tests
ii)
Power frequency puncture withstand voltage
iii)
Steep front wave test to be conducted as follows:
- This test shall be performed on five samples taken at random
- The insulators shall be subjected to five(5) positive and five (5) negative
impulses with wave fronts of at least 2500 kV/microsecond
- In the case of low flashover values of porcelain puncture, the number of
samples shall be doubled or another test shall be performed.
iv)
c)
Results of the second test should not show porcelain puncture
Acceptance Tests for Disc Insulators:
i)
Visual examination
ii)
Verification of Dimensions
iii)
Temperature Cycle Test
iv)
Puncture Test
v)
Galvanizing Test
vi)
Mechanical performance Test
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/33
vii) Test on locking device for ball and socket coupling
viii) Porosity test
ix)
d)
Type Test on Hardware Fittings Only:
i)
e)
Electromechanical test
Magnetic power loss test for suspension assembly (For both suspension and
drop clamps)
Acceptance Test on Hardware Fitting:
i)
Visual Examination
ii)
Verification of Dimensions
iii)
Galvanizing/Electroplating tests
iv)
Slip strength test
v)
Shore hardness test for Elastometer (if applicable)
vi)
Mechanical strength test for each component (including corona control rings
and arcing horns)
vii) Mechanical strength test on corona control rings
viii) Test on locking devices for ball and socket coupling
f)
g)
h)
i)
Routine Test on Disc Insulator/Long Rod Insulator:
i)
Visual Inspection
ii)
Mechanical Routine Test
iii)
Electrical Routine Test
Routine Test of Hardware Fittings:
i)
Visual examination
ii)
Mechanical strength test
Test During Manufacture on all Components as Applicable on Disc Insulator:
i)
Chemical analysis of zinc used for galvanizing
ii)
Chemical analysis, mechanical hardness tests and magnetic particle
inspection for malleable casting
Test During Manufacture on all Components as Applicable on Hardware Fittings:
i)
Chemical analysis of zinc used for galvanizing
ii)
Chemical analysis, mechanical hardness tests and magnetic particle
inspection for forgings.
iii)
Chemical analysis and mechanical hardness tests and magnetic particle
inspection for fabricated hardware.
Test Procedures
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/34
a)
Voltage Distribution Test(Dry)
The string shall be energised with 100 kV power frequency voltages. The voltage
across each insulator unit shall be measured by using a high impedance voltmeter.
The voltmeter shall be calibrated before and after the measurement. The voltage
across any disc shall not exceed 9% of the applied voltage for single and double
suspension insulator string and 10% for double tension insulator strings.
b)
Corona Extinction Voltage Test (Dry)
The sample assembly when subjected to power frequency voltage shall be as per
relevant IEC standard. There shall be no evidence of corona on any part of the
sample when all possible sources of corona are photographed in a darkened room.
c)
RIV Test (Dry)
Under the conditions as specified under b) above the insulator string along with
complete hardware fittings, RIV test shall be done and the test procedure shall be
in accordance with IEC-60437-1973.
d)
Mechanical Strength Test
The complete insulator string along with its hardware fittings shall be subjected to
a load equal to 50% of the specified minimum ultimate tensile strength (UTS)
which shall be increased at a steady rate to 67% of the minimum UTS specified.
The load shall be held for five minutes and then removed. After removal of the
load, the string components shall not show any visual deformation and it shall be
possible to disassemble them by hand. Hand tools may be used to remove cotter
pins and loosen the nuts initially. The string shall then be reassembled and loaded
to 50% of UTS and the load shall be further increased at a steady rate till the
specified minimum UTS and held for one minute. No fracture should occur during
this period. The applied load shall then be increased until the failing load is reached
and the value recorded.
e)
Magnetic Power Loss Test for suspension assembly (for both drop and suspension
clamp)
Two hollow aluminium tubes of 32 mm dia. shall be placed 450 mm or 250 mm
apart depending upon the voltage level at which test is to be done. An alternating
current in the range of 200 to 600 Amps. shall be passed through each tube. The
reading of the wattmeter with and without two suspension assemblies along with
the line side yoke plate clevis eye shall be recorded. Not less than three suspension
assemblies shall be tested. The average power loss for the suspension assembly
shall be plotted for each value of current. The value of loss corresponding to 300
Amps shall be read from the graph. The magnetic power loss of the clamp
assembly with entire line fitting shall not exceed 4 watts at 600 Amps current
(rms).
f)
Mechanical Strength Test of each component
The load shall be so applied that the component is stressed in the same way as it
would be in actual service and the procedure as given in f) above should be
followed.
g)
Chemical Analysis of Zinc used for galvanizing
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/35
Samples taken for the zinc ingot shall be chemically analyzed as per relevant
IECStandard. The purity of zinc shall be not less than 99.5%.
h)
Test for Forgings, Castings & Fabricated Hardware
The chemicals analysis, mechanical hardness tests and magnetic particle
inspection, shall be as per the internationally recognized procedures for these tests.
The sampling shall be based on heat number and heat treatment batch. The details
regarding test shall be mutually agreed to by the Contractor and the Employer.
3.4.12
Interlocking Facilities
Disconnectors, earthing switches, circuit breakers, etc., shall be provided with an
interlocking system which ensures safe operation of the equipment under all
service conditions.
The interlocking scheme shall be designed for the final substation arrangement.
The items of plant supplied under this Contract shall be complete with all
interlocking facilities needed for the final arrangement, avoiding the need for
future modifications.
Where mechanical key interlocks are employed, they shall be effective at the point
where hand-power is applied so that stresses cannot be transferred to parts remote
from that point.
Tripping of the circuit-breaker shall not occur if any attempt is made to remove a
trapped key from the mechanism. Emergency tripping devices shall be kept
separate and distinct from any key interlocking system and shall be clearly
labelled, suitably protected from inadvertent operation but readily accessible.
Circuit-breakers shall be interlocked so that, except under maintenance conditions,
it is not possible to close a circuit-breaker unless the selected busbar and circuit
disconnectors are closed.
Except as stated below, disconnectors shall be so interlocked that they cannot be
operated unless the associated circuit-breaker is open. Where power transformers
are banked together, the individual transformer disconnectors shall be interlocked
so that it is not possible to make or break load current at the disconnectors.
Provision for on load transfer of feeder circuits from one busbar to another shall be
made possible by interlocks which ensure that the section disconnectors, bus
coupler and its disconnectors are closed.
All electrical interlocks shall so function as to interrupt the operating supply, and
an approved system of interlocks shall be provided which shall cover the
emergency hand operation of apparatus which is normally power operated. Failure
of supply (or its restoration after an outage) or of connections to any electrical
interlock shall not produce or permit faulty operation. Electrical bolt interlocks
shall be energised only when the operating mechanism is being operated. Visible
indication shall be provided to show whether the mechanism is locked or free.
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/36
Approved means, normally padlocked, shall be provided whereby the bolt can be
operated in the emergency of a failure of interlock supplies.
3.4.13
Auxiliary Switches and Contactors
Circuit-breakers, disconnectors and earthing devices and circuit selector
disconnectors shall be provided with suitably rated auxiliary switches and
contactors, where permitted, to relay circuit information for the purpose of control,
protection, indication and metering at the substation site as required by the relevant
section of the Specification. In addition they shall be provided with auxiliary
contacts for position indication to the central system control room via the remote
supervisory system. Disconnector auxiliary switches are not to be used for current
transformer switching circuits.
Auxiliary contactors shall be provided only where the circuit requirement cannot
be met by the auxiliary switch arrangements and multiple contactors and relays
will not be accepted in lieu of the auxiliary switches except as specifically
approved by the Engineer. Auxiliary switches and contactors shall comply with the
requirements of this Specification and in particular shall be capable of operation
within the same voltage limits as specified for the associated circuit-breaker close
and trip coils.
The connections of all auxiliary switches, including spares, and contactors as well
as the associated coil connections and interconnections between auxiliary switches,
shall be wired to a terminal board located in the operating cubicle or other
approved position.
Auxiliary switches and contactors shall be mounted in an approved accessible
position clear of the main operating mechanism but with a minimum of additional
mechanical linkages and housed in a substantial weatherproof enclosure. Where
adjustable linkages are provided to facilitate the timing of the auxiliary switches
with respect to the main equipment, approved locking devices shall be fitted.
Auxiliary switch contacts shall be positively operated, make with a wiping action
and, where necessary, discharge resistors shall be provided to prevent arcing when
breaking inductive circuits.
Except for the contacts employed for control and interlocking, the requirements for
auxiliary switches in respect of timing shall be as follows:For Circuit-Breakers
Normally open contacts, with the exception of two sets of this type, shall close in
about 10 milliseconds after the making of the main circuit-breaker contacts and
shall open in about 10 milliseconds before the separation of the main
circuit-breaker contacts whilst the two remaining sets shall close in about 5
milliseconds before the making of the main circuit breaker contacts and open
simultaneously with the main circuit contacts.
Normally closed contacts shall close 10 milliseconds after the opening of the main
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/37
circuit-breaker contacts and open at least 10 milliseconds before the making of the
main circuit-breaker contacts.
For Busbar Disconnectors
The operating sequence of any disconnector auxiliary switches used in D.C.
circuits for high impedance busbar zone protection shall be such that the auxiliary
switches operate:a)
before reaching the pre-arcing distance on closing the disconnector.
b)
after the pre-arcing distance has been exceeded on the opening of the disconnector.
Auxiliary switches shall be adjustable from normally-open to normally-closed or
vice-versa.
For Line Disconnectors
As for Busbar disconnector auxiliary switches.
For Earthing Switches
As for Busbar disconnector auxiliary switches.
3.5
Indoor Metal Clad Switchgear and Construction Requirement
3.5.1
deleted
3.6
Interference with Existing Equipment
Work carried out on site in extending equipment or modifying the existing
substation shall be so arranged as to cause minimum interference with existing
plant and equipment and interruption to supplies. The Contractor shall include in
his price for the provision, erection, commissioning and subsequent dismantling
and removal from site of any temporary structures, insulators and connections that
may be necessary to maintain continuity of supply whilst certain sections of the
plant are out of service to permit the execution of the Works.
If it is necessary to reposition any of the existing substation plant in order to
incorporate the specified works or to comply with specific requirements, all costs
incurred in dismantling, removing, modifying, repositioning, existing and
commissioning of such equipment shall be deemed to have been included in the
Bid Price.
The repositioning of any plant is subject to the specific approval of the Employer.
Existing plant rendered redundant by this Contract shall remain the property of the
Employer and shall be returned to the Employer's store.
Permission for access to existing substations to execute the Works shall be
obtained in writing from the Employer. The Contractor shall conform to the
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/38
Employer's Safety Rules in all respects when working in or near existing plant.
Extensions at the existing substation shall be carried out maintaining the same
busbar centres, heights etc., other essential dimensions and interlocking schemes.
Where stated in the Schedule of Requirements, equipment for existing substations
shall be of the same type and manufacture as that already in service.
SEC 03: HV AIR INSULATED SWITCHGEAR EQUIPMENT
3/39
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 4
TRANSFORMER
SECTION 4
TRANSFORMERS
TABLEOF CLAUSES
4.1SCOPE
4/5
4.2 REFERENCES ....................................................................................................................... 4/5
4.2.1 IEC STANDARDS .................................................................................................................... 4/5
4.2.2 BRITISH STANDARDS ............................................................................................................. 4/5
4.2.3 BS EUROPEAN STANDARDS ................................................................................................... 4/6
4.3 POWER TRANSFORMERS ................................................................................................... 4/6
4.3.1 TYPE OF TRANSFORMER AND OPERATING CONDITION .......................................................... 4/6
4.3.2 CONTINUOUS MAXIMUM RATING .......................................................................................... 4/7
4.3.3 ELECTRICAL CONNECTIONS .................................................................................................. 4/7
4.3.4 ABILITY TO WITHSTAND SHORT CIRCUIT .............................................................................. 4/7
4.3.5 LOSSES AND EVALUATION OF LOSSES ................................................................................... 4/8
4.3.6 IMPEDANCE ........................................................................................................................... 4/9
4.3.7 NOISE
4/9
4.3.8 HARMONIC SUPPRESSION...................................................................................................... 4/9
4.4 MAGNETIC CIRCUIT AND WINDINGS ............................................................................. 4/9
4.4.1 MAGNETIC CIRCUIT............................................................................................................... 4/9
4.4.2 FLUX DENSITY..................................................................................................................... 4/10
4.4.3 WINDINGS ........................................................................................................................... 4/10
4.4.4 INTERNAL EARTHING .......................................................................................................... 4/11
4.5 TANK AND ANCILLARY .................................................................................................... 4/12
4.5.1 TRANSFORMER TANKS......................................................................................................... 4/12
4.5.2 CONSERVATOR TANKS, BREATHERS AND AIR DRYERS ........................................................ 4/13
4.5.3 VALVES 4/13
4.5.4 JOINTS AND GASKETS.......................................................................................................... 4/14
4.5.5 PRESSURE RELIEF DEVICE .................................................................................................. 4/15
4.5.6 EARTHING TERMINALS ........................................................................................................ 4/15
4.5.7 RATING, DIAGRAM AND VALVE PLATES............................................................................... 4/15
4.5.8 NUTS & BOLTS OF TRANSFORMER TANKS........................................................................... 4/16
4.6 COOLING PLANT ................................................................................................................ 4/16
4.6.1 COOLING PLANT GENERAL .................................................................................................. 4/16
4.6.2 RADIATORS CONNECTED DIRECTLY TO TANK ..................................................................... 4/16
4.6.3 COOLER BANKS ................................................................................................................... 4/16
SEC 04: Transformer
4/1
4.6.4 FORCED COOLING ............................................................................................................... 4/16
4.6.5 OIL PIPES AND FLANGES ..................................................................................................... 4/17
4.6.6 AIR BLOWERS ...................................................................................................................... 4/17
4.6.7 COOLER CONTROL ............................................................................................................... 4/17
4.7VOLTAGE CONTROL .......................................................................................................... 4/18
4.7.1 GENERAL4/18
4.7.2 ON-LOAD TAP CHANGERS .................................................................................................... 4/19
4.7.3 AUTOMATIC VOLTAGE CONTROL ......................................................................................... 4/20
4.7.4 VOLTAGE REGULATING RELAYS .......................................................................................... 4/21
4.7.5 REMOTE CONTROL PANEL................................................................................................... 4/21
4.7.6 OFF-LOAD TAP CHANGERS .................................................................................................. 4/22
4.8 SUPERVISORY CONTROL ................................................................................................. 4/23
4.8.1 REQUIREMENTS ................................................................................................................... 4/23
4.9 TERMINAL BUSHING AND CONNECTIONS ................................................................. 4/24
4.9.1 BUSHINGS............................................................................................................................ 4/24
4.9.2 OIL/SF6 GAS BUSHINGS...................................................................................................... 4/24
4.9.3 CABLE BOXES ...................................................................................................................... 4/24
4.9.4 OPEN AIR TERMINAL BUSHINGS ......................................................................................... 4/25
4.9.5 TERTIARY AND NEUTRAL TERMINATIONS ........................................................................... 4/26
4.9.6 MOUNTING OF BUSHINGS.................................................................................................... 4/26
4.9.7 BUSHING CURRENT TRANSFORMER (BCT) ......................................................................... 4/27
4.10 AUXILIARY POWER AND CONTROL CABLES ............................................................. 4/27
4.10.1 SCOPE OF SUPPLY ............................................................................................................. 4/27
4.10.2 GENERAL ........................................................................................................................... 4/27
4.11 TEMPERATURE AND ALARM DEVICES ...................................................................... 4/27
4.11.1 TEMPERATURE INDICATING DEVICES AND ALARMS .......................................................... 4/27
4.11.2 GAS AND OIL-ACTUATED RELAYS ..................................................................................... 4/28
4.12SHIPMENT AND DRYING OUT CASTING ..................................................................... 4/29
4.12.1 SHIPMENT ......................................................................................................................... 4/29
4.12.2 DRYING OUT...................................................................................................................... 4/29
4.13TRANSFORMER OIL AND TREATMENT ....................................................................... 4/30
4.13.1 TRANSFORMER OIL............................................................................................................ 4/29
4.13.2 OIL PURIFIER EQUIPMENT ................................................................................................ 4/30
4.13.3 OIL STORAGE..................................................................................................................... 4/30
4.13.4 COLLAPSIBLE OIL CONTAINERS ........................................................................................ 4/30
4.14EARTHING/AUXILIARY TRANSFORMER ..................................................................... 4/30
4.14.1 GENERAL ........................................................................................................................... 4/31
4.14.2 ELECTRICAL AND SHORT CIRCUIT CHARACTERISTICS ...................................................... 4/32
SEC 04: Transformer
4/2
4.14.3 TANKS AND FITTINGS ........................................................................................................ 4/32
4.14.4 SECONDARY WINDINGS ..................................................................................................... 4/32
4.14.5 TERMINAL CONNECTIONS ................................................................................................. 4/33
4.15 INSPECTION AND TESTING .......................................................................................... 4/33
4.16 FIRE PROTECTION SYSTEM .......................................................................................... 4/33
4.16.1GENERAL ............................................................................................................................ 4/33
4.16.2 NITROGEN FIRE FIGHTING ................................................................................................ 4/34
4.16.3FIRE WALL ......................................................................................................................... 4/40
SEC 04: Transformer
4/3
SEC 04: Transformer
4/4
SECTION 4
POWER TRANSFORMERS
4.1
SCOPE
These clauses describe the General Technical Requirements for Power
Transformers and shall be read in conjunction with the Requirements in Volume
1 of 2.
“Installation, testing & commissioning of power transformer shall be done by
the transformer engineer(s) of the power transformer manufacturer(s).”
4.2
4.2.1
REFERENCES
Any international standards referenced in the specifications and our outdated shall be
replaced with the corresponding replacement.
IEC Standards
IEC 60044
Instrument transformers-Part 1: Current transformers
IEC 60044
Instrument transformers-Part 2: Inductive volatage Transformers
IEC 60060
High voltage testing techniques (Part 1 & 2)
IEC 60099
Surge arrestors (Part 4 & 5)
IEC 60076Power transformers (Parts 1, 2, 3, 4, 5, 6, 7, 8 & 10)
IEC 60137
Insulated bushings for alternating voltages above 1000V
IEC 60214
Tap changers (Parts 1 & 2)
IEC 60228
Conductors of insulated cables
IEC 60270
Recommendation for partial Discharge measurements
IEC 60296
Specification for unused mineral insulating oils for transformers and
switchgear
IEC 60422
Supervision and maintenance guide for mineral insulating oils in electrical
equipment
IEC 60439
Low voltage switchgear and controlgear assemblies (Parts 1 & 2)
IEC 60529
Degrees of protection provided by enclosures
IEC 60815
Guide to the selection of insulators in respect of polluted condition
4.2.2
British Standards
BS 61
Specification for threads for light gauge copper tubes and fittings
BS 381C-1996 Color Standards for General Purpose
BS 729
Hot Dip Galvanizing
BS 2569-2
Cleaning Before Painting
BS 3600
Specification for dimensions and masses per unit length of welded and
seamless steel pipes and tubes for pressure purposes
BS 4504
Circular flanges for pipes, valves and fittings (PN designated)
BS 5493
Code of practice for protective coating of iron and steel structures against
corrosion
BS 6121
Mechanical cable glands
BS 6346:1989 Specification for PVC insulated cables for electricity supply
SEC 04: Transformer
4/5
BS 6435
Specification for unfilled enclosures for the dry termination of HV cables for
transformers and reactors
BS 7354
Code of practice for design of HV open terminal stations
4.2.3
BS European Standards
BS EN 10029 Specification for tolerances on dimensions, shape and mass for hot rolled steel
plates 3mm thick and above
4.3
4.3.1
POWER TRANSFORMERS
Types of Transformer and Operating Conditions
i) General
The transformers shall be oil immersed and suitable for outdoor installation and
shall comply with IEC 60076, Parts 1 to 8 & 10 inclusive.
Electrical clearances shall not be less than as stated in the Project Requirements
in Volume 1, whichever is the greater.
ii) Cooling
The types of cooling shall be as stated in the Schedule A of Requirements and the
letters relating to the method of cooling used in this Specification and Schedules
shall be in accordance with IEC 60076.
Where a combination of three/two methods of cooling is applied to one
transformer, as for ONAN/ONAF units for 230/132/33kV transformer and
ONAN/ONAF units for 132/33 kV transformer, the transformer shall be capable
of operating under the ONAN condition as stated in the Schedule of
Requirements, after which the cooling equipment is to come into operation and
the Transformer will operate as an ONAF unit.
Failure of one fan shall not reduce the continuous maximum rating of the
transformer.
iii)Parallel Operation
Transformers supplied against each item shall be designed to operate satisfactory,
one with the other, when operating on the same tap position.
iv) Handling on Site
For installation purposes and to permit the moving of transformer, the
transformers are to be equipped with castors (rail wheels). A permanent rail
transfer track system shall be provided, integrated with the transformer
foundations. The castors should be able to swivel in both the longitudinal and
transverse directions.
SEC 04: Transformer
4/6
A system of wedges shall be included to stop any unwanted movement of the
transformer during its operating life. The distance between rails must be
compatible with the transformer dimensions and also the rail gauge prevailing at
existing substation sites.
4.3.2
Continuous Maximum Rating
Transformers shall have the rating stated in the Schedule of Requirements and
shall comply with the requirements as regards temperature rise and overloads on
all tappings, irrespective of the direction of power flow and with the voltage of
the lower voltage winding at the normal voltage stated in the Schedule of
Requirements. To allow for high atmospheric temperatures, the allowable
temperature rises shall be reduced in accordance with IEC 60076-2.
The overload capability shall be in accordance with IEC 60076-7.
4.3.3
Electrical Connections
Transformer windings shall be connected in accordance with the Vector group
symbol specified in the Schedule of Requirements and as per IEC 60076.The
neutral point of star connected winding shall be brought out for grounding.
All electrical connections within windings shall be brazed but, subject to
approval, mechanically crimped joints may be used for round stranded conductors
on tapping, bushing or earthing connections and on bundle conductors where
design has been proved by type test and application is subject to rigorous quality
control.
4.3.4
Ability to Withstand Short Circuit
i)General
All transformers shall be capable of withstanding, on any tappings and without
damage, the thermal and dynamic effects of external short circuits under the
conditions stated in IEC 60076 Part 5. For this purpose the design short circuit
level for each system voltage is stated in the Schedule of Requirements.
ii) Calculations and Tests
Evidence shall be submitted with the Bid as to the extent to which the
manufacturer has proved, or is able to prove, either by calculation or test, the
ability of the specified Transformers to withstand short circuit.
The Bidder shall provide with his Bid a brief description of those transformers, or
parts thereof, which have been subjected to short circuit test or for which short
circuit calculations are available. It is preferred that this information relates to
designs comparable with the transformers tendered but, in the event this is not so,
the Engineer reserves the right to require calculations to prove that the design of
transformers tendered will satisfactorily comply with this Clause.
SEC 04: Transformer
4/7
4.3.5
Losses and Evaluation of Losses
Guaranteed values for component losses of the total loss which shall be as low as
is consistent with transport restrictions, reliability and economic use of materials,
shall be as stated in the Schedule E of Particulars and Guarantees.
Bids will be assessed on the basis of the least 'Present Worth' of capital cost plus
guaranteed losses, being the sum of the installed Bid Price of the transformers
plus a sum which shall be:For each unit of the three-phase 230/132/33kV, 225/300 MVA (ONAN/ONAF)
power transformer,
Evaluated price of transformer loss = N.a + L.b + M.c
Where
N
L
=
=
M
=
a
b
c
=
=
=
No load loss (core-loss) at rated voltage in kW
Load loss (copper-loss) at 75°C, 50 Hz maximum continuous
rating in kW
Total load of transformer cooling fans at transformer maximum
continuous rating in kW (when all the cooling fans are in
operation)
Cost/kW of no load loss (core-loss) valued at Taka 112,000.00
Cost/kW of load loss (copper-loss) valued at Taka 58,000.00
Cost/kW of auxiliary power valued at Taka 58,000.00
For each unit of the three-phase 132/33 kV, 50/75 MVA (ONAN/ONAF) power
transformer,
Evaluated price of transformer loss = N.a + L.b + M.c
Where
N
L
=
=
M
=
a
b
c
=
=
=
No load loss (core-loss) at rated voltage in kW
Load loss (copper-loss) at 75°C, 50 Hz maximum continuous
rating in kW
Total load of transformer cooling fans at transformer maximum
continuous rating in kW (when all the cooling fans are in
operation)
Cost/kW of no load loss (core-loss) valued at Taka 112,000.00
Cost/kW of load loss (copper-loss) valued at Taka 58,000.00
Cost/kW of auxiliary power valued at Taka 58,000.00
The acceptance of transformers yielding component losses higher than the
guaranteed values shall be governed by either of the following:(a) Component losses in excess of guaranteed values but within the tolerance
permitted under IEC 60076 Part 1.
Transformers shall be acceptable subject to full compliance with all technical
SEC 04: Transformer
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particulars, including temperature rises at CMR and subject to the Bidder
accepting deduction from the Contract Price of charges for each kW or part
thereof of component losses in excess of the guaranteed values, at the above
evaluation rates.
(b) Component losses in excess of guaranteed values and exceeding the tolerance
permitted under IEC 60076 Part 1.
The acceptance of transformers shall be entirely at the discretion of the Employer
and subject to the Bidder accepting the deduction from the Contract Price of
charges for each kW or part thereof of component losses in excess of the
guaranteed values, at the above loss evaluation rates.
In the event of transformers yielding component and total losses which are either
equal to or below the guaranteed values, the Bidder will not be entitled to any
premium in respect of reduction in losses below the guaranteed values.
4.3.6
Impedance
The value of impedance measured on various tapping’s shall be as stated in the
Schedule and minimum and maximum values where stated in the Schedule A of
Requirements shall be guaranteed by the Contractor.
4.3.7
Noise
The transformer noise levels shall be measured as a type test and in accordance
with IEC 60076-10. The acceptance level of the transformers shall be as stated in
the Schedule of Requirements.
4.3.8.
Harmonic Suppression
Transformers shall be designed with particular attention to the suppression of
harmonic voltages, especially the third, fifth and seventh harmonics, and to
minimize the detrimental effects resulting therefrom.
4.4
MAGNETIC CIRCUIT AND WINDINGS
4.4.1. Magnetic Circuit
The core winding structure and major insulation shall be such as to permit an
unobstructed flow of cooling oil over the core and through the core cooling ducts
to ensure efficient cooling of the core and where required of flux shunts and tie
rods/bars.
The magnetic circuit shall be insulated from core bolts and supporting frame
work and be capable of withstanding a test voltage to core bolts and to the frame
of 2.5 kV r.m.s for one minute. Two separate insulated removable bolted earthing
links shall be provided for earthing of the core and of the core-supporting
SEC 04: Transformer
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framework to the exterior of the tank. These links shall be located in a covered
box at the top of the transformer and arranged so they are accessible for testing
purpose without opening up the transformer. Alternatively connection to both the
core and the frame may be made via two externally bolted links within an access
box fitted with an oil tight cover near the base of the tank.
The core shall be earthed via copper straps inserted in each group of core packets
separated by oil ducts or other insulating materials: and at a minimum of four (4)
points distributed evenly across the width of the core.
4.4.2
Flux Density
Cores shall be constructed from cold rolled grain oriented steel sheets. Design
shall be such that there will be no adverse effects due to core or stray flux heating
with the quality of steel employed, and that when operating under the most
onerous conditions envisaged in IEC 60076 and IEC 60354, flux density in any
part of the magnetic circuit does not exceed 1.9 Tesla.
4.4.3
Windings
i) Construction of Windings
Transformer star connected windings shall have graded insulation as defined in
IEC 60076. For 33kV and below they shall have uniform insulation as defined in
IEC 60076. All neutral points shall be insulated to withstand the applied test
voltage specified in the Schedule of Requirements.
The windings shall be located in a manner which will ensure that they remain
electromagnetically balanced and that their magnetic centers remain coincident
under all conditions of operation.
The windings shall also be thoroughly dried and shrunk by the application of
axial pressure for such length of time as will ensure that further shrinkage will not
occur in service.
The windings and leads of all transformers shall be braced to withstand the
shocks which may occur through rough handling and vibration during transport,
switching and other transient service conditions including external short circuit.
If the winding is built up of sections or of disc coils separated by spacers, the
clamping arrangements shall ensure that equal pressures are applied to all
columns of spacers.
ii) Tertiary Windings
The tertiary winding of 230/132/33kV power transformer shall be adequately
rated for the specified load and its average and hot spot winding gradients at the
specified load shall not exceed the specified temperature rise for winding average
and winding hot spot when added to the mean oil and top oil temperature rises
SEC 04: Transformer
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measured during the temperature rise test on the HV and LV temperature rise
tests.
The tertiary winding shall further have adequately conductor cross sectional area
and mechanical strength to withstand a through fault on the tertiary terminals and
the fault current present in that winding during line to ground fault on the HV and
LV phase terminals and without exceeding the maximum permitted current
density and temperature rise limits calculated in accordance with IEC 60076-5
Clause 4.1.4.
4.4.4
Internal Earthing
i) General
All metal parts of the transformer, with the exception of the individual core
laminations, core bolts and associated individual clamping plates, shall be
maintained at some fixed potential.
ii) Earthing of Core Clamping Structure
The top main core clamping structure shall be connected to the tank body by a
copper strap. The bottom main core clamping structure shall be earthed by one or
more of the following methods:(a)by connection through vertical tie rods to the top structure;
(b)by direct metal-to-metal contact with the tank base maintained by the weight
of the core and windings;
(c)by connection to the top structure on the same side of the core as the main
earth connection to the tank.
iii) Earthing of Magnetic Circuits
The magnetic circuit shall be earthed to the clamping structure at one point only
through a removable link placed in an accessible position just beneath an
inspection opening in the tank cover and which, by disconnection, will enable the
insulation between the core and clamping plates, etc., to be tested at voltages up
to 2.5 kV. The link shall have no detachable components and the connection to
the link shall be on the same side of the core as the main earth connection. These
requirements are compulsory.
All insulating barriers within magnetic circuits shall be bridged by means of
aluminium or tinned copper strips, so inserted as to maintain electrical continuity.
iv) Earthing of Coil Clamping Rings
Where coil clamping rings are of metal at earth potential, each ring shall be
connected to the adjacent core clamping structure on the same side of the
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Transformer as the main earth connection.
v) Size of Earthing Connections
Main earthing connections shall have a cross-sectional area of not less than 80
sq.mm but connections inserted between laminations may have cross-sectional
areas reduced to 20 mm2 when in close thermal contact with the core.
4.5
TANKS AND ANCILLARY EQUIPMENT
4.5.1
Transformer Tanks
Each transformer shall be enclosed in a suitably stiffened welded steel tank such
that the transformer can be lifted and transported without permanent deformation
or oil leakage. The construction shall employ weldable structural steel of an
approved grade to BS EN 10029. The final coat colour of transformers shall be to
Munsell 5Y-7/1. The On-load tap changer tank shall be separated from the main
tank of the transformer.
Lifting lugs shall be provided, suitable for the weight of the transformer,
including core and windings, fittings, and with the tank filled with oil. Each tank
shall be provided with at least four jacking lugs, and where required, with lugs
suitably positioned for transport on a beam transporter. Haulage lugs should also
be provided to enable a cable to be used safely for haulage in any direction.
The transformer tank shall be capable of withstanding a full vacuum when empty
of oil, without any significant permanent deformation or damage.
All joints, other than those which may have to be broken, shall be welded.
The tank and cover shall be designed in such a manner as to leave no external
pockets in which water can lodge no internal pockets in which oil can remain
when draining the tank or in which air can be trapped when filling the tank, and
to provide easy access to all external surfaces for painting.
Where cooling tubes are used, each tube shall be of heavy gauge steel welded into
the tank sides, top and bottom.
Each tank cover shall be of adequate strength, must not distort when lifted and
shall be provided with suitable flanges having sufficient and properly spaced
bolts. Inspection openings shall be provided to give access to the internal
connections of bushings, winding connections and earthing links. Each opening
shall be correctly located and must be of ample size for the purpose for which it is
intended. All inspection covers shall be provided with lifting handles.
It must be possible to remove any bushing without removing the tank cover.
SEC 04: Transformer
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Pockets shall be provided for a stem type thermometer and for the bulbs of
temperature indicators where specified. These pockets shall be located in the
position of maximum oil temperature and it must be possible to remove any bulb
without lowering the oil level in the tank. Captive screwed caps shall be provided
to prevent the ingress of water to the thermometer pockets when they are not in
use.
A ladder shall be provided on one side of the tank as a means for inspection and
access to the top of the transformer. The lower section of the ladder shall be
equipped with a barrier complete with provision for locking with a padlock.
4.5.2
Conservator Tanks, Breathers and Air Dryers
Each transformer shall be provided with an overhead conservator tank formed of
substantial steel plates and arranged above the highest point of the oil circulating
system (see also Clause 4.6.1). Connections into the main tank shall be at the
highest point to prevent the trapping of air or gas under the main tank cover.
The capacity of conservator tank shall be adequate for the expansion and
contraction of oil in the whole system under the specified operating conditions.
Conservator tanks shall also be provided with a cleaning door, filling cap, drain
valve with captive cap and an oil level indicator with minimum and maximum
levels indicated. The normal level at an oil temperature of 25°C shall be indicated
and the minimum and maximum levels shall also be correlated with oil
temperature markings. The temperature markings shall preferably be integral with
the level indicating device.
The pipework between the conservator and the transformer tank shall comply
with the requirements of Clause 4.6.1 and a valve shall be provided at the
conservator to cut off the oil supply to the tank.
The conservator shall be fitted with an air cell which shall be connected to a silica
gel breather of a type which permits the silica gel content to be removed for
drying. Due to the climatic conditions at site, this breather shall be larger than
would be fitted for use in a temperate climate. All breathers shall be mounted at a
height of approximately 1400 mm above ground level.
A completely separate conservator shall be provided for the OLTC. This
conservator shall be fitted with: an oil level gauge, a desiccant breather, isolating
valves shall be provided for connection from OLTC conservator connection pipe
to OLTC and to connection breather, an oil sump drain valve for sump, a filling
cap and a removable end plate for inspection and repainting.
4.5.3
Valves
Each transformer shall be fitted with the following valves as a minimum
requirement:Main Tank
SEC 04: Transformer
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(A)One 50mm bore filter valve located near to the top of the tank.
(B)One 50 mm bore filter valve located near to the bottom of the tank and
diagonally opposite to the filter valve required against (A). Where design
permits, this valve may be combined with item (C).
(C)One 50mm drain valve with such arrangements as may be necessary inside the
tank to ensure that the tank can be completely drained of oil as far as
practicable. This valve shall also be provided with an approved oil sampling
device.
(D)One valve between the main tank and gas actuated relay, complete with
bypass facility to facilitate removal of relay and maintain oil flow.
Conservator
(E)One valve between the conservator and gas actuated relay for the main tank
and, where appropriate, for the tap change diverter switch tank complete with
bypass pipe work for Buchholz relay to facilitate maintenance of the relay.
(F) One drain valve for oil conservator tank so arranged that the tank can be
completely drained of all oil.
Tap Changer
(G)50mm filter and 50mm drain valve where selector switches are contained in a
separate tank.
Diverter Switch Tank
(H)One drain valve to be fitted to each tank.
Radiators and Cooler Banks
(I) Valves at each point of connection to the tank and in accordance with
Clauses 4.6.2 and 4.6.3.
The two valves (D) and (E) arrangement across the gas actuated relay are to be
connected with a oil pipe work bypass facility to facilitate removal of the relay,
due to failure etc, and still maintain the oil flow system between the conservator
and main tank.
Blank flanges, plates or captive screw caps shall be fitted to all valves and pipe
ends not normally connected in service.
The omission of any, or the provision of alternative arrangements to the above
requirements, will not be accepted unless approved in writing by the Employer
before manufacture.
SEC 04: Transformer
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4.5.4
Joints and Gaskets
All joint faces shall be arranged to prevent the ingress of water or leakage of oil
with a minimum of gasket surface exposed to the action of oil or air.
Oil resisting synthetic rubber gaskets are not permissible except where the
synthetic rubber is used as a bonding medium for cork, or similar material, or
where metal inserts are provided to limit compression.
Gaskets shall beas thin as possible consistent with the provision of a good seal
and full details of all gasket sealing arrangements shall be shown on the Plant
drawings.
4.5.5
Pressure Relief Device
An approved pressure relief device of sufficient size for the rapid release of over
pressure that may be generated in the tank, and designed to operate at a static
pressure lower than the hydraulic test pressure, shall be provided. It shall be of
the spring operated valve type ("Qualitrol" or equivalent) and shall be provided
with one set of normally open signaling contacts which will be used for trip alarm
purposes.
The relief device is to be mounted on the tank cover and is to be provided with a
skirt to project at least 25mm into the tank to prevent gas accumulation.
Discharge of oil shall be directed away from the transformer top cover and clear
of any operating position.
4.5.6
Earthing Terminals
Two substantial steel flag type terminals having two 14mm diameter holes on
55mm centers shall be located one on either side and near to the bottom of the
transformer to facilitate connection to the local earthing system.
4.5.7
Rating, Diagram and Valve Plates
The following plates, or an approved combined plate, shall be fixed to each
transformer tank at an average height of 1500mm above the ground level:(A)A rating plate bearing the data specified in IEC 76 Part 1. This plate shall also
include the short-circuit current rating and time-factor for each winding.
(B)A diagram plate showing in an approved manner the internal connections and
the voltage vector relationship of the several windings, in accordance with IEC 76
Part 1 with the transformer voltage ratio for each tap and, in addition, a plan view
of the transformer giving the correct physical relationship of the terminals.
(C)A plate showing the location and function of all valves and air release cocks or
plugs. This plate shall also if necessary warn operators to refer to the
SEC 04: Transformer
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Maintenance Instructions before applying vacuum.
Plates are to be of stainless steel or other approved material capable of
withstanding the rigours of continuous outdoor service at site.
4.5.8
Nuts & Bolts of Transformer Tanks
All nuts & bolts of transformer shall be stainless steel.
4.6
COOLING PLANT
4.6.1
Cooling Plant General
Radiators and coolers shall be hot-dip galvanized, designed so that all painted
surfaces can be thoroughly cleaned and easily painted in situ with brush or spray
gun. The design shall also avoid pockets in which water can collect and shall be
capable of withstanding the pressure tests specified in Section 15 for the
transformer main tank.
The clearance between any oil or other pipework and live parts shall be not less
than the minimum clearances stated in the Schedule of Requirements.
4.6.2
Radiators Connected Directly to Tank
Where built-on radiators are used, each radiator shall be connected to the main
tank through flanged valves. Plugs shall be fitted at the top of each radiator for air
release and at the bottom for draining.
A valve shall be provided on the tank at each point of connection to the tank.
4.6.3
Cooler Banks
Each cooler bank shall be provided with:(A)A valve at each point of connection to the tank.
(B)A valve at each point of connection of radiators.
(C)Loose blanking plates for blanking off the main oil connections.
(D)A 50mm filter valve at the top of each cooler bank.
(E)A 50mm drain valve at the lowest point of each interconnecting oil pipe.
(F) A thermometer pocket, fitted with captive screw cap, in the inlet and in the
outlet oil pipes.
(G)Air release and drain plugs on each radiator.
The omission of any or the provision of alternative, arrangements to the above
requirements will not be accepted unless approved in writing by the Engineer
before manufacture.
4.6.4
Forced Cooling
The type of forced cooling shall be as stated in the Schedule of Requirements.
SEC 04: Transformer
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Forced cooling equipment for transformers of similar rating and design shall be
completely interchangeable, one with the other, without modification on Site.
4.6.5
Oil Pipes and Flanges
All oil piping necessary for the connecting of each transformer to its conservator,
cooler banks etc. shall be supplied and erected under this Contract.
The oil piping shall be of approved material with machined flanged joints.
Copper pipework is to comply with BS 61.
Dimensions of steel pipes shall be in accordance with BS 3600 and the drilling of
all pipe flanges shall comply with BS 4504.
An approved expansion piece shall be provided in each oil pipe connection
between the transformer and each oil cooler bank.
All necessary pipe supports, foundation bolts and other attachments are to be
provided.
It shall be possible to drain any section of pipe work independently of the rest and
drain valves or plugs shall be provided as necessary to meet this requirement.
4.6.6
Air Blowers
Air blowers for forced air cooling shall be of approved make and design and be
suitable for continuous operation out-of-doors. They shall also be capable of
withstanding the stresses imposed when brought up to speed by the direct
application of full line voltage to the motor.
To reduce noise to the practical minimum, motors shall be mounted
independently from the coolers or, alternatively, an approved form of antivibration mounting shall be provided.
It shall be possible to remove the blower, complete with motor, without
disturbing or dismantling the cooler structure framework.
Blades shall be of material subject to approval.
Blower casings shall be made of galvanized steel of thickness not less than
2.6mm (14 S.W.G.) and shall be suitably stiffened by angles or tees.
Galvanized wire guards with mesh not exceeding 12.5mm shall be provided to
prevent accidental contact with the blades. Guards shall also be provided over all
moving parts. Guards shall be designed such that blades and other moving parts
can not be touched by test fingers to IEC 60529.
4.6.7
Cooler Control
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Where forced cooling using multiple small single-phase motors is employed, the
motors in each cooling bank shall be grouped so as to form a balanced threephase load.
Each motor or group of motors shall be provided with a three-pole electrically
operated contactor and with control gear of approved design for starting and
stopping manually.
Where forced cooling is used on transformers, provision shall be included under
this Contract for automatic starting and stopping from contacts on the winding
temperature indicating devices as specified. The control equipment shall be
provided with a short time delay device to prevent the starting of more than one
motor, or group of motors in the case of multiple cooling, at a time.
Where motors are operated in groups, the group protection shall be arranged so
that it will operate satisfactorily in the event of a fault occurring in a single motor.
The control arrangements are to be designed to prevent the starting of motors
totaling more than 15kW simultaneously, either manually or automatically. Phase
failure relays are to be provided in the main cooler supply circuit.
All contacts and other parts which may require periodic renewal, adjustment or
inspection shall be readily accessible.
All wiring for the control gear accommodated in the marshalling kiosk, together
with all necessary cable boxes and terminations and all wiring between the
marshalling kiosk and the motors, shall be included in the Contract.
An alarm of indicating“Transformer Cooling Fault” is to be provided and
initiated in the event of any ventilation/cooling motor trip, or failure of either
main or control supplies.
4.7
VOLTAGE CONTROL
4.7.1
General
Transformers shall be provided with tap changers for varying the effective
transformation ratio. Control schemes of on load tap change shall utilize 110V ac
centre tap earthed voltage derived from the 415V, 3 phase, 4 wire system. Phase
failure relays shall be provided to ensure a secure supply.
Number and range of taps shall be as called for in the Schedule A of
Requirements.
All terminals shall be clearly and permanently marked with numbers
corresponding to the cables connected thereto.
Tap positions shall be numbered consecutively, ranging from one upwards. The
SEC 04: Transformer
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tap positions shall be numbered so that by raising the tap position the LV voltage
is increased.
4.7.2
On-Load Tap Changers
i) General
On-load tap changers shall be MR Germany or ABB Sweden make and comply
with IEC 60214 and shall be suitable for power flow in both directions. Only
designs which have been type tested in accordance with these standards will be
accepted.
Current making and breaking switches associated with the tap selectors or
otherwise where combined with tap selectors shall be contained in a tank in
which the head of oil is maintained by means completely independent of that on
the transformer itself. Details of maintaining oil separation, oil levels, detection of
oil surges and provision of alarm or trip contacts will be dependent on the design
of tap-changer and be to the approval of the Engineer.
ii) Mechanisms
The tap change mechanism shall be designed such that when a tap change has
been initiated, it will be completed independently of the operation of the control
relays and switches. If a failure of the auxiliary supply during tap change or any
other contingency would result in that movement not being completed an
approved means shall be provided to safeguard the transformer and its auxiliary
equipment.
Limit switches shall be provided to prevent over-running of the tap changing
mechanism. These shall be directly connected in the operating motor circuit. In
addition, mechanical stops shall be fitted to prevent over-running of the
mechanism under any conditions. For on-load tap change equipment these stops
shall withstand the full torque of the driving mechanism without damage to the
tap change equipment.
Thermal devices or other approved means shall be provided to protect the motor
and control circuit.
A permanently legible lubrication chart shall be provided and fitted inside the tap
change mechanism chamber.
iii) Local and Remote Control
Equipment for local, manual and electrical operation shall be provided in a
cubicle complying with Section 2. A thermostat controlled anti-condensation
heater is to be provided in the cubicle. Electrical remote control equipment shall
also be supplied as specified in the Schedule A - Scope of Work.
The following operating conditions are to apply to the on-load tap changer
SEC 04: Transformer
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controls:(A)It must not be possible to operate the electric drive when the manual operating
gear is in use.
(B)It must not be possible for two electric control points to be in operation at the
same time.
(C)Operation from the local or remote control switch shall cause one tap
movement only, unless the control switch is returned to the off position
between successive operations.
(D)It must not be possible for any transformer operating in parallel with one or
more transformers in a group to be out of step with the other transformers in
the group. Any deviation in the position of tap changers has to stop further
function of the AVR. (Out of step protection)
(E)All electrical control switches and local manual operating gear shall be clearly
labeled in an approved manner to indicate the direction of tap changing, i.e.
raise and lower tap number.
(F) Emergency stop push-button at local and remote control positions.
iv) Indications
Apparatus of an approved type shall be provided on each transformer:(A)To give indication mechanically at the transformer and electrically at the
remote control point of the number of the tapping in use.
(B)To give electrical indication, separate from that specified above, of tap
position at the remote supervisory point.
(C)To give indication at the remote control point and at the supervisory control
point that a tap change is in progress; this indication to continue until the tap
change is completed.
(D)To give indication at the remote control point and at the supervisory control
point when the transformers operating in parallel are operating out of step.
(E)To indicate at the tap change mechanism the number of operations completed
by the equipment.
4.7.3
Automatic Voltage Control
Automatic Control shall be suitable for control of transformers in parallel.
In addition to the methods of control covered by Clause 4.7.2, the following
methods shall also be provided.
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(A)Automatic Independent - It shall be possible to select automatic independent
control for each transformer irrespective of the method of control selected for
any other of the associated transformers.
(B)Automatic parallel - It shall be possible to select any transformer for master or
follower control.
It must not be possible to operate any tap changer by supervisory, remote or local
electrical hand control while the equipment is switched for automatic operation.
4.7.4
Voltage Regulating Relays
Automatic voltage control shall be initiated by a voltage regulating relay of an
approved type and suitable for flush mounting. The relay shall operate from the
nominal reference voltage stated in the Schedule of Requirements derived from a
circuit mounted LV voltage transformer having Class 1.0 or 0.5 accuracy
toIEC 60186 and the relay voltage reference balance point shall be adjustable.
The relay bandwidth shall preferably be adjustable to any value between 1.5
times and 2.5 times the transformer tap step percentage, the nominal setting being
twice the transformer tap step percentage.
The relay shall be insensitive to frequency variation between the limits of 47Hz
and 51Hz. The relay shall be complete with a time delay element adjustable
between 10 and 120 seconds. The relay shall also incorporate an under voltage
blocking facility which renders the control inoperative if the reference voltage
falls below 80 percent of the nominal value with automatic restoration of control
when the reference voltage rises to 85 percent of nominal value.
On each transformer the voltage transformer supply to the voltage regulating
relay shall be monitored for partial or complete failure. The specified indicating
lamp and alarm will be inoperative when the circuit- breaker controlling the lower
voltage side of the transformer is open and also that when the tap changer is on
control other than automatic control.
Parallel operation and Master/follower facilities shall have to be provided in the
AVR relay.The AVR relay shall be fully integrated into the substation automation
system and all AVR related operations shall be securely performed from the
Substation Automation System. The Substation Automation supplier shall be
responsible for integrating the AVR relay.
4.7.5
Remote Control Panels
The remote control panels specified in the Schedule A of Requirements shall be
floor mounted sheet steel cubicles of approved type, layout and colour to Munsell
5Y-7/1 and shall be provided for each transformer. Each shall form a complete
enclosure with lockable rear doors and shall be fitted with interior lamp, door
switch, heaters, cable gland plates for bottom entry of cables and all other
SEC 04: Transformer
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equipment to provide the features specified, the standard requirements (which
may be varied to suit manufacturer's design) being as follows:
Instruments:
Voltmeter (voltage at the low voltage terminals of the transformer).
Tap position indicator with integral or separate scale to indicate the no-load LV
voltage in kV appropriate to each winding tap.
Relays:
Automatic voltage control.
Controls:
Automatic/Non-automatic voltage control selector switch
Remote/Supervisory tap change control selector switch
Pistol grip selector switch with centre zero
Independent/Master/Follower selector switch
AVR voltage reference adjuster
Indications and Alarms:
Tap change in progress - white lamp
Tap change out of step - amber lamp
Tap change incomplete - amber
Tap change control on "local"
Tap change control on auto/manual
Group 1 Air forced cooling equipment running - white
Group 1 Air forced cooling overcurrent alarm - amber
Group 2 Air forced cooling equipment running - white
Group 2 Air forced cooling overcurrent alarm - amber
Forced cooling failure-amber lamp
VT Fail alarm - amber
Supply voltage to OLTC failure - amber lamp
Remote control schemes shall be entirely suitable for operation with the distance
between the transformer and remote control panels as shown on the Specification
drawings.
4.7.6
Off-Load Tap Changers
The off-circuit tapping’sfor Auxiliary transformer shall be provided on the higher
voltage windings for variation of no-load primary voltage as specified in the
Schedule of Requirements.
Off-load tap-changing shall be carried out by means of an external hand-operated
tapping switch mounted on the side of the tank. All phases of the tapping switch
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must be operated by one hand wheel.
The tapping switch shall have a spring-loaded captive bolt or other approved
means on the moving part which positively locates the switch correctly at each
tapping position. This bolt must be lockable at each tapping position and shall be
provided with a suitable padlock and keys. Moving the switch from one tapping
position to another shall require that the bolt be withdrawn by hand from its
locating socket on the transformer tank against the spring pressure.
Tap-position numbers corresponding to the tapping switch bolt-locating sockets
shall be cast or engraved in a metal indication plate fixed to the tank and a keyed
metal pointer on the tapping switch operating handle shall show clearly at which
tapping number the transformer is operating.
All tap-position indicators shall be marked with one integer for each tap position,
beginning at number 1. Adjacent taps shall be numbered consecutively in such a
manner that when moving a tap to a new tapping position which has a higher
number, the no-load output voltage of the untapped winding increases.
4.8
SUPERVISORY CONTROL
4.8.1
Requirements
Transformer tap change control will be effected from the substation control room
with facilities for remote control from the Load Dispatch Centre. All necessary
connections, indications, auxiliary switches, relays and changeover switches to
meet supervisory control requirements shall be provided and connected under this
Contract to terminal blocks in the remote control panels. The supply and
installation of the multicore control cables between the remote control panels and
the Plant/Telecontrol Interface Cubicle shall be provided under the Contract.
The following supervisory facilities are required:
Controls:
i) Supervisory selection of auto/non auto voltage control.
ii) Tap change raise/lower by direct operation of tap changer.
iii) Tap change blocking on/off.
iv) Remote/Supervisory selection "Override".
v) Parallel/Independent control.
Indications and Alarms:
i) Tap position indication
ii) Tap change out of step alarm
iii) Buchholz and winding temperature non-trip alarm
iv) Tap change control on Local/Supervisory
v) Parallel/Independent, master/follower
vi) Tap change blocking on/off
SEC 04: Transformer
4/23
vii)Tap change control on Automatic/Manual
All contacts for supervisory alarms and indications shall be potential free.
4.9
4.9.1
TERMINAL BUSHINGS AND CONNECTIONS
Bushings
Where stated in the Schedule of Requirements, transformers are to be provided
with outdoor type porcelain bushing insulators.
All bushings shall comply with IEC 60137 and the minimum creepage distance
for outdoor bushings shall not be less than 25mm per kV of rated voltage
between phases.
Outdoor bushing insulators shall be provided with adjustable arcing horns and for
rated voltages of 36kV and lower these shall be of the duplex gap type.
Bushings shall be of sealed construction suitable for service under the very
humid conditions at
Site and, addition, for the very rapid cooling of equipment exposed to direct
sunlight when this is followed by sudden heavy rainstorms.
Typical sections of bushing insulators showing the internal construction, method
of securing the top cap and methods of sealing shall be included in the Bid.
The 230kV and 132kV outdoor immersed bushings shall be oil impregnated
paper insulated condenser type and have no communication with the oil in the
transformer. An oil gauge shall be provided to indicate that the correct level is
maintained. 33kV bushings shall be oil filled or solid type.
Completely immersed bushings and lower voltage outdoor immersed bushings
may be of other type of construction, subject to the approval of the Engineer but
bushings of resin bonded paper construction are not permitted.
On all condenser bushings a tapping shall be brought out to a separate terminal
for testing purposes on Site.
Special precautions shall be taken to exclude moisture from paper insulation
during manufacture, assembly, transport and erection.
4.9.2
Porcelain
Hollow porcelain shall meet the test requirements of IEC 60233 and shall be
sound, free from defects and thoroughly verified. Designs based on jointed
porcelains will not be acceptable. The glaze must not be depended upon for
insulation. The glaze shall be smooth, hard, of a uniform shade of brown and
shall cover completely all exposed parts of the insulator. Outdoor insulators and
fittings shall be unaffected by atmospheric conditions producing weathering,
acids, alkalis, dust and rapid changes in temperature that may be experienced
under working conditions.
SEC 04: Transformer
4/24
The porcelain must not engage directly with hard metal and, where necessary,
gaskets shall be interposed between the porcelain and the fittings. All porcelain
clamping surfaces in contact with gaskets shall be accurately ground and free
from glaze.
All fixing material used shall be of suitable quality and properly applied and
must not enter into chemical action with the metal parts or cause fracture by
expansion in service. Cement thicknesses are to be as small and even as possible
and proper care is to be taken to centre and locate the individual parts correctly
during cementing.
All porcelain insulators shall be designed to facilitate cleaning.
4.9.3
Marking
Each porcelain insulator shall have marked upon it the manufacturer's name or
identification mark and year of manufacture. These marks shall be clearly legible
after assembly of fittings and shall be imprinted before firing, not impressed.
When a batch of insulators bearing a certain identification mark has been
rejected, no further insulators bearing this mark shall be submitted and the
Contractor shall satisfy the Engineer that adequate steps will be taken to mark or
segregate the insulators constituting the rejected batch in such a way that there
can be no possibility of the insulators being re-submitted for the test or supplied
for the use of the Employer.
Each complete bushing shall be marked with the manufacturer's name or
identification mark, year of manufacture, serial number, electrical and
mechanical characteristics in accordance with IEC 60137:1973.
4.9.4
Deleted
4.9.5
Tertiary and Neutral Terminations
Terminations of delta connected tertiary windings and neutral ends of windings
shall be as follows;
a) Delta Connected Tertiary Windings
Delta connected tertiary windings for local AC distribution shall be terminated as
open air terminal bushings.
Where current transformers are specified in the Schedule of Requirements or on
the Drawings, these shall be included on this Contract.
b) Neutral Ends of Windings
Neutral ends of the three phase windings shall be connected at a point accessible
from a handhole at the transformer tank top cover. Where current transformers
are specified at the neutral ends before the neutral connection of the windings, to
be used in conjunction with a protection, they shall be installed such that access is
SEC 04: Transformer
4/25
possible through the same handhole and maintenance of these CT, if need be, can
be carried out without lowering the transformer oil below the core and winding.
The star connection shall then be brought out via one outdoor bushing insulator
capable of withstanding an AC power frequency test.
4.9.6
Mounting of Bushings
Bushing insulators shall be mounted on the tank in a manner such that the
external connections can be taken away clear of all obstacles. Neutral bushings
shall be mounted in a position from which a connection can be taken to a neutral
current transformer mounted on a bracket secured to the transformer tank.
The clearances from phase to earth must not be less than those stated in the
Schedule A of Requirements.
A flexible pull-through lead suitably sweated to the end of the winding copper
shall be provided for the bushings and is to be continuous to the connector which
is housed in the helmet of the bushings.
When bushings with an under-oil end of a re-entrant type are used the associated
flexible pull-through lead is to be fitted with a suitably designed gas bubble
deflector.
The bushing flanges must not be of re-entrant shape which may trap air.
Clamps and fittings made of steel or malleable iron shall be galvanized and all
bolt threads are to be greased before erection.
4.9.7
Bushing Current Transformer (BCT)
BCT particulars are stated in the Schedule A of Requirements.
4.10
AUXILIARY POWER AND CONTROL CABLES
4.10.1 Scope of Supply
This Contract includes the supply, installation and termination of the necessary
auxiliary power and control cables within items of plant supplied under the
Contract.
The Contractor shall produce, during the currency of the Contract and in any case
before shipment of plant commences, detailed cable core schedules for each
transformer.
4.10.2 General
Auxiliary power and control cables shall have copper conductors, PVC insulated,
armoured and PVC sheathed overall. The cable design shall generally be in
SEC 04: Transformer
4/26
accordance with BS 6346:1989and Section 6 of this Specification.
All cables installed under the Contract shall utilize compression glands of type E1
to BS.6121 or otherwise designed to secure armour wires and bond them to
earthed metal and to provide seals between sheath and gland and between inner
sheath and threaded fixing component.
The Contractor shall supply and fit the compression gland and make off
individual cores on to the terminal boards, including the supply and fitting of
numbered markers on each core.
4.11
TEMPERATURE AND ALARM DEVICES
4.11.1 Temperature Indicating Devices and Alarms
The transformers shall be provided with approved devices of Kilhstrom or
equivalent for indicating the top oil temperature and hottest spot winding
temperatures. The devices shall have a dial type indicator and, in addition, a
pointer to register the highest temperature reached. Each winding temperature
device shall have three separate contacts fitted, one of which shall be used to
control the cooling plant motors, one to give an alarm and one to trip the
associated circuit-breakers.
To simulate indication of the hottest spot temperature of the winding the device
shall comprise a current transformer associated with one phase only and a heating
device designed to operate continuously at 130 percent of transformer CMR
current and for 30 minutes at 150 percent of CMR current, associated with a
sensing bulb installed in an oil tight pocket in the transformer top oil.
The winding temperature indicators (WTI) shall be housed in the marshalling
cubicle. The tripping contacts of the winding temperature indicators shall be
adjustable to close between 80oC and 150oC and to re-open when the temperature
has fallen by not more than 10oC.
The alarm contacts and the contacts used to control the cooling plant motors on
the above devices shall be adjustable to close between 50oC and 100oC and to reopen when the temperature has fallen by a desired amount between 10oC and
15oC.
All contacts shall be adjustable to a scale and must be accessible on removal of
the relay cover. Alarm and trip circuit contacts shall be suitable for making or
breaking 150 VA between the limits of 30 volts and 250 volts AC or DC and of
making 500 VA between the limits of 110 and 250V DC. Cooler motor control
contacts shall be suitable for operating the cooler contactors direct or, if
necessary, through an interposing relay.
The temperature indicators in the marshalling kiosk shall be so designed that it is
possible to move the pointers by hand for the purpose of checking the operation
of the contacts and associated equipment.
SEC 04: Transformer
4/27
The working parts of the instrument shall be made visible by the provision of cutaway dials and glass-fronted covers and all setting and error adjustment devices
shall be easily accessible.
Connections shall be brought from the device to terminal boards placed inside the
marshalling cubicle.
Terminals, links and a 63mm moving iron ammeter shall be provided in the
marshalling kiosk for each WTI for:(A)Checking the output of the current transformer.
(B)Testing the current transformer and thermal image characteristics.
(C)Disconnecting the bulb heaters from the current transformer secondary circuit
to enable the instrument to be used as an oil temperature indicator. Links
shall be provided as shown on the drawing enclosed with this Specification.
4.11.2
Gas and Oil-Actuated Relays
Each transformer shall be fitted with gas and oil-actuated relay equipment having
alarm contacts which close on collection of gas or low oil level, and tripping
contacts which close following oil surge conditions.
Each gas and oil-actuated relay shall be provided with a test cock to take a
flexible pipe connection for checking the operation of the relay.
Each relay shall be fitted with a calibrated glass window for indication of gas
volume.
To allow gas to be collected at ground level, a small bore pipe shall be connected
to the gas release cock of the gas and oil-actuated relay and brought down to a
point approximately 1400mm above ground level, where it shall be terminated by
a cock which shall have provision for locking to prevent unauthorized operation.
The design of the relay mounting arrangements, the associated pipe work and the
cooling plant shall be such that maloperation of the relay will not take place under
normal service conditions, including starting or stopping of oil circulating pumps,
whether by manual or automatic control under all operating temperatures.
The pipe work shall be so arranged that all gas arising from the transformer will
pass into the gas and oil-actuated relay. The oil circuit through the relay must not
form a delivery path in parallel with any circulating oil pipe, nor is it to be teed
into or connected through the pressure relief vent. Sharp bends in the pipe work
shall be avoided.
For two conservators piped separately to the transformer, one Gas and Oil
actuated relay shall be installed in the main tank and an Oil-flow relay shall be
SEC 04: Transformer
4/28
installed in the OLTC conservator.
4.12
SHIPMENT AND DRYING OUT
4.12.1 Shipment
Each transformer, when prepared for shipment, shall be fitted with a shock
indicator or recorder which shall remain in situ until the transformer is delivered
to site. In the event that the transformer is found to have been subjected to
excessive shock in transit, such examination as is necessary shall be made in the
presence of the Engineer.
Where practicable, transformers shall be shipped with oil filling to cover core and
windings but, when shipped under pressure of gas, shall be fitted for the duration
of delivery to site and for such time thereafter as is necessary, with a gauge and
gas cylinder adequate to maintain internal pressure above atmospheric.
4.12.2 Drying Out
All transformers shall be dried out by an approved method at the manufacturer's
works and so arranged that they might be put into service without further drying
out on Site.
Clear instructions shall be included in the Maintenance Instructions regarding any
special precautionary measures (e.g. strutting of tap changer barriers or tank
cover) which must be taken before the specified vacuum treatment can be carried
out. Any special equipment necessary to enable the transformer to withstand the
treatment shall be provided with each transformer.
4.13
TRANSFORMER OIL AND TREATMENT
4.13.1 Transformer Oil
The Contractor shall supply the first filling of all insulating oil required for the
operation of the Plant and, after treatment, a test shall be made in the Engineer's
presence to prove that the breakdown voltage is at least 60kV at 2.5mm electrode
gap.The transformer oil shall be new, inhibited, naphthenic based mineral oil, free
from additives. It shall be acid-refined and pre-treated and shall have properties
complying with IEC 60296-class II.
4.13.2
Oil Purifier Equipment
The oil purifier equipment is to be mounted on a steerable trailer equipped with pneumatic
types, over-run and parking brakes and weatherproof canopy. The equipment shall be
capable of purification of oil to IEC 60296 and IEC 60422, shall be of the replaceable
paper filter type and shall have the following facilities:(A) Oil treatment rate not less than 6000 litres per hour.
(B) Water extraction capability down to 5 ppm.
SEC 04: Transformer
4/29
(C) Reduction of dissolved gas content to 1% by volume or less.
(D) Filtration level less than 1 micron.
(E) Oil transfer, vacuum pumps and heaters suitable for 40OV, 3 phase 50Hz, 4 wire,
supply.
(F) Vacuum capability approximately 1 Torr.
(G) Facility to apply vacuum to transformer tank during oil filling.
(H) Two 15m lengths of wire reinforced hose coloured differently for clean and dirty oil.
(I)Facility for "closed loop" operation.
(J) One 20m length of power supply cable with plug and socket at the filter end only.
4.13.3
Oil Storage
As required by Clause 4.13.1, the Contractor shall supply the first filling of transformer
oil. It is envisaged that the oil will be supplied to site in 200kg drums and filtered by use
of the plant described in the preceding paragraph into a storage tank prior to transfer
again via filter plant into the transformer.
Storage tanks shall be painted internally and externally and shall be equipped with:
4.13.4
-
50mm top inlet and bottom outlets with blank flanges.
-
50mm drain valve.
-
Oil level indicator.
-
Hand hole.
-
Silica gel breather.
Collapsible Oil Containers
This section covers the design, manufacture and supply of 10000 litre and 20000 litre
capacity two collapsible oil container suitable for on-site storing, transferring and
transporting transformer oil associated with the transformers being supplied under the
Contract.
Each container shall be made up of one or several layers (and securely bonded
together) of tough polymer and textile material which can be folded with ease for
transportation purposes. The outer surface of the container shall be coated with a tough
abrasion resistant compound and on the inner face with a polymer compatible with the
transformer oil.
The containers shall be provided with the following fittings:(A) Controllable inlet and outlet valves constructed from brass or aluminium alloy and a
gun metal outlet plug.
SEC 04: Transformer
4/30
(B) Air vent plug(s) for air release during oil filling and located at the centre and top of
eachcontainer.
(C) Two sets of special tools, gauges and spanners necessary to operate and maintain
thevalves, plugs etc.
The guarantee period is 36 months from the date certified in the Final Acceptance
Certificate.
The following details are to be submitted with the proposal to supply the oil container.
i)
Descriptive literature and technical specification of the container design.
ii)
Manufacturer's production capability and supply record for at least 5 years
serviceexperience.
iii) Test certification record.
iv) Type reference number, capacity, weight and dimensions (laid flat unfilled and
maximumfilled height).
4.14
EARTHING/AUXILIARY TRANSFORMERS
4.14.1
General
Earthing transformers shall comply with IEC 60076-6 and shall be of the oil
immersed ONAN type suitable for outdoor installation. They are to have a main
interconnected star winding brought out via oil/air terminal bushings, which will
be directly connected to the lower voltage terminals of the associated system
transformer.
The neutral point of the interconnected star winding shall be brought out of the
tank through a bushing insulator. This point maybe isolated or connected to earth
directly or through a resistance in order to provide an earthing point for the
neutral of the system.
The earthing transformers shall have a secondary winding to supply the
substation auxiliary load. The voltage ratio shall be 33/0.415kV. The
star-connected secondary windings shall be arranged to give a three-phase, four
wire supply with the star point solidly earthed. The secondary winding shall have
a continuous rating as stated in the Schedule of Requirements and shall conform
to IEC 60076.
4.14.2
Electrical and Short Circuit Characteristics
Earthing transformers will normally have their neutral points connected to earth
via a resistance which limits earth fault current to the full load current at the
associated power transformer. However, provision is made for solidly earthing
the neutral points and, under this condition, the earthing transformers shall be
capable of withstanding, both thermally and mechanically without damage, for a
period of 5 seconds the application of normal three phase line voltage to the
SEC 04: Transformer
4/31
terminals of the interconnected star winding with one line terminal earthed. The
current density of the winding under this condition shall not exceed 50A/mm2.
In addition, the interconnected star winding of each earthing transformer, when at
its maximum temperature due to continuous full load on the auxiliary winding,
shall be designed to carry for 10 seconds without injurious heating an earth fault
current in the neutral connection as specified. The current density under such
conditions shall not exceed 23A/mm2.
4.14.3
Tanks and Fittings
Earthing transformers shall be provided with the following fittings:
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H)
(1)
(J)
4.14.4
Conservator vessel with removable end cover and prismatic oil gauge.
Buchholz relay.
One thermometer pocket with captive screw cap.
Silica gel breather of the oil seal type.
Pressure relief device.
Filter valve and combined filter and drain valves.
Oil sampling device.
Rating plate.
Tank earth terminals.
Lifting lugs.
Secondary Windings
The three-phase, four-wire secondary windings shall be terminated at a three-pole
MCCB unit with bolted neutral link and gland entry for a four-core solid
dielectric cable. This shall be accommodated in a lockable, fully weatherproof
compartment together with a neutral earthing link. The purpose of the neutral
earthing link is to connect the 400V system neutral to earth. It shall be connected
between the transformer winding end and a suitably located earthing terminal to
which the system earth can be connected.
The windings shall be fitted with off-load tap changer to vary the voltage ±5
percent of the nominal open circuit value in 2.5 percent steps.
4.14.5
Terminal Connections
The 33 kV side of the earthing transformers shall be fitted with oil/air terminal
bushings. The earth point connection to the neutral earthing resistor shall be via a
33 kV conductor.
4.15
INSPECTION AND TESTING
Inspection and testing of transformers during manufacture and after installation
on site shall be in accordance with Section 15 of this Specification.
SEC 04: Transformer
4/32
4.16
FIRE PROTECTION SYSTEM
4.16.1 General
This Sub-clause covers the design and performance requirements of :
Nitrogen Gas Injection Fire Fighting for the transformer ONAN/ONAF.
It is not intended to completely specify all details of design and construction.
Nevertheless, the system design and equipment shall conform in all respects to high
standard of engineering, design and workmanship and shall be capable of performing in
continuous commercial operation in a manner acceptable to the Employer. The system
design shall also conform to TAC/ NFPA norms.
The system offered shall comply with the relevant International Standards, conforming to
any other approved international standards shall meet the requirements called for in the
latest revision of relevant International Standard.
Ambient temperature for design of all equipment shall be considered as 45°C.
The system shall be reliable without making any mal operation. Even if undesirable
nitrogen gas injection is made into the transformer tank under normal transformer
condition without the internal faults, restoration of transformer by vacuum oil purification
up to re-energizing shall complete as soon as possible after the undesiredgas injection.
In case of an event of the control power failure, the system shall be able to be operated
manually.
Various equipment to performthe required fire protection shall be provided under this
Contract.
Reference of standards is listed below. Relevant International Standards other than BS
standards shall be subject to approval by the Employer:
BS Standards
BS 381 C
Colours for Identification, Coding & Special Purpose
BS 7629-1
Specification for 300/500 V fire resistant electric cables having low emission
of smoke and corrosive gases when affected by fire.
BS 8434-1
Methods of test for assessment for power integrity of electric cables
BS 5839-1
Code
of
practice
system
design,
installation,
commissioning
and
maintenance for fire detection and fire alarm system
BS EN50267-2-1 Common Test Methods for Cables Under Fire Conditions
4.16.2 Nitrogen Fire Fighting
(1) Nitrogen Fire Fighting
SEC 04: Transformer
4/33
The detail description of fire protection system is given below. Accordingly the
Contractor has to make necessary provisions in consultation with supplier of NIFPS for
satisfactory operation without affecting the overall performance of transformer.
Oil filled transformer / reactor shall be provided with a dedicated Nitrogen Injection Fire
Protection System (NIFPS) for the ratings, mentioned in SLD which shall use nitrogen
as
fire
quenching
medium.
The
fire
protective
system
shall
prevent
transformer/Reactor oil tank explosion and possible fire in case of internal faults. In the
event of fire by external causes such as bushing fire, OLTC fires, fire from surrounding
equipment etc, it shall act as a fast and effective fire fighter. It shall accomplish its role
as fire preventer and extinguisher without employing water and / or carbon dioxide.
Fire shall be extinguished within 3 minutes (maximum) of system activation and within
30 seconds (maximum) of commencement of nitrogen injection. The fire protection
system shall have been in successful operation in for at least last three years for
protection of transformers of 230/132/33 kV and higher voltage class. The list of past
supplies in local market along with performance certificate from users of the system
shall be submitted for approval.
(2)
Activation of the fire protective system
Mal-functioning of fire prevention/ extinguishing system could lead to interruption in
power supply. The bidder shall ensure that the probability of chances of malfunctioning
of the fire protective system is practically zero. To achieve this objective, the bidder
shall plan out his scheme of activating signals which should not be too complicated to
make the fire protective system inoperative in case of actual need. The system shall
be provided with automatic control for fire prevention and fire extinction. Besides
automatic control, remote electrical push button control at Control box and local
manual control in the fire extinguishing cubicle shall also be provided. The following
electrical-signals shall be required for activating the fire protective system under
prevention mode / fire extinguishing mode.
(3)
Auto Mode
(a)
For prevention of fire:
Differential relay operation
Buchholz relay paralleled with pressure relief valve or RPRR (Rapid Pressure Rise
Relay)
Tripping of all circuit breakers (on HV &LV/IV side) associated with transformer /
reactor is the pre-requisite for activation of system
(b)
For extinguishing fire
Fire detector
Buchholz relay paralleled with pressure relief valve or RPRR (Rapid Pressure Rise
Relay)
SEC 04: Transformer
4/34
-
Tripping of all circuit breakers (on HV &LV/IV side) associated with transformer /
reactor is the pre-requisite for activation of system.
(4)
Manual Mode (Local / Remote)
Tripping of all circuit breakers (on HV &LV/IV side) associated with transformer /
reactor is the pre-requisite for activation of system
(5)
Manual Mode (Mechanical)
The system shall be designed to be operated manually in case of failure of power
supply to fire protection system
(6)
Description
Nitrogen injection fire protection system should be a dedicated system for each oil
immersed transformer / reactor. It should have a Fire Extinguishing Cubicle (FEC)
placed on a plinth at a distance of 5-10 m away from transformer / reactor or placed
next to the fire wall (if fire fighting wall exists). The FEC shall be connected to the top
of transformer/reactor oil tank for depressurization of tank and to the oil pit (capacity
is approximately equal to 10% of total volume of oil in transformer/reactor tank) from
its bottom through oil pipes. The fire extinguishing cubicle should house a pressurized
nitrogen cylinder(s) which is connected to the transformer oil tank at bottom. The
Transformer Conservator Isolation Valve (TCIV) is fitted between the conservator
tank and Buchholz relay. Cable connections are to be provided from signal box to the
control box in the control room, from control box to fire extinguishing cubicle and from
TCIV to signal box. Fire detectors placed on the top of transformer/reactor tank are to
be connected in parallel to the signal box by Fire survival cables. Control box is also
to be connected to relay panel in control room for receiving system activation signals.
(7)
Operation
On receipt of all activating signals, the system shall drain pre-determined volume of
hot oil from the top of tank (i.e. top oil layer), through outlet valve, to reduce tank
pressure by removing top oil and simultaneously injecting nitrogen gas at high
pressure for stirring the oil at pre-fixed rate and thus bringing the temperature of top
oil layer down. Transformer conservator isolation valve blocks the flow of oil from
conservator tank in case of tank rupture / explosion or bushing bursting. Nitrogen
occupies the space created by oil drained out and acts as an insulating layer over oil
in the tank and thus preventing aggravation of fire.
(8)
System components
Nitrogen injection fire protection system shall broadly consist of the following
components. However, all other components which are necessary for fast reliable
and effective working of the fire protective system shall deemed to be included in the
scope of supply.
(a) Fire Extinguishing Cubicle (FEC)
SEC 04: Transformer
4/35
The FEC shall be made of CRCA sheet of 3 mm (minimum) thick complete with the base
frame, painted inside and outside with post office red colour (shade to be in line with BS:
381 C : 1988 – Colors for Identification, Coding and Special Purposes). It shall have
hugged split doors fitted with high quality tamper proof lock. The degree of protection
shall be IP55. The following items shall be provided in the FEC.
-
Nitrogen gas cylinder with regulator and falling pressure electrical contact manometer.
-
Oil drain pipe with mechanical quick drain valve.
-
Electro mechanical control equipment for draining of oil of pre-determined volume and
injecting regulated volume of nitrogen gas
-
Pressure monitoring switch for back-up protection for nitrogen release
-
Limit switches for monitoring of the system
-
Butterfly valve with flanges on the top of panel for connecting oil drain pipe and
nitrogen injection pipes for transformer/reactors
-
Panel lighting (CFL Type)
-
Oil drain pipe extension of suitable sizes for connecting pipes to oil pit.
-
Space heater
-
Others if necessary
(b) Control box
Control box is to be placed in the control room for monitoring system operation,
automatic control and remote operation. The following alarms, indications, switches,
push buttons, audio signal etc. shall be provided.
-
System on
-
TCIV open
-
Oil drain valve closed
-
Gas inlet valve closed
-
TCIV closed*
-
Fire detector trip *
-
Buchholz relay trip
-
Oil drain valve open*
-
Extinction in progress *
-
Cylinder pressure low *
-
Differential relay trip
-
PRV / RPRR trip
-
Transformer/reactor trip
SEC 04: Transformer
4/36
-
System out of service *
-
Fault in cable connecting fault fire detector
-
Fault in cable connecting differential relay
-
Fault in cable connecting Buchholz relay
-
Fault in cable connecting PRV / RPRR
-
Fault in cable connecting transformer /reactor trip
-
Fault in cable connecting TCIV
-
Auto/ Manual / Off
-
Extinction release on / off
-
Lamp test
-
Visual/ Audio alarm*
-
Visual/ Audio alarm for DC supply fail *
-
Space heater
-
Others if necessary
* Suitable provision shall be made in the control box, for monitoring of the system
from remote substation using the substation automation system.
(c)
Transformer Conservator Isolation Valve
Transformer conservator isolation valve (TCIV) to be fitted in the conservator pipe line,
between conservator and buchholz relay which shall operate for isolating the conservator
during abnormal flow of oil due to rupture / explosion of tank or bursting of bushing. The
valve shall not isolate conservator during normal flow of oil during filtration or filling or
refilling, locking plates to be provided with handle for pad locking. It shall have proximity
switch for remote alarm, indication with visual position indicator.
(d) Fire Detectors
The system shall be complete with adequate number of fire detectors (quartz bulb) fitted
on the top cover of the transformer / reactor oil tank.
(e) Signal Box
It shall be mounted away from transformer / reactor main tank, preferably near the
transformer marshalling box, for terminating cable connections from TCIV & fire
detectors and for further connection to the control box. The degree of protection shall be
IP55
(f)
Cables
Fire survival cables (capable to withstand 750° C.) of 4 core x 1.5 sq. mm size for
connection of fire detectors in parallel shall be used. The fire survival cable shall conform
to BS 7629-1, BS 8434-1 and BS 5839-1, BS EN 50267-2-1 or relevant International
standards.
SEC 04: Transformer
4/37
Fire Retardant Low Smoke (FRLS) cable of 12 core x 1.5 sq. mm size shall be used for
connection of signal box / marshalling box near transformer/reactor and FEC mounted
near transformer/reactor with control box mounted in control room.
Fire Retardant Low Smoke (FRLS) cable of 4 core x 1.5 sq. mm size shall be used for
connection between control box to DC and AC supply source, fire extinguishing cubicle
to AC supply source, signal box/ marshalling box to transformer conservator isolation
valve connection on transformer/reactor.
(g) Pipes
Pipes complete with connections, flanges, bends and tees etc. shall be supplied along
with the system.
(9) Other items
(a) Oil drain and nitrogen injection openings with gate valves on transformer / reactor tank
at suitable locations.
(b) Flanges with dummy piece in conservator pipe between Buchholz relay and
conservator tank for fixing TCIV.
(c) Fire detector brackets on transformer / reactor tank top cover.
(d) Spare potential free contacts for activating the system i.e. in differential relay, Buchholz
relay, Pressure Relief Device / RPRR, Circuit Breaker of transformer/reactor
(e) Pipe connections between transformer / reactor and FEC and between FEC and oil pit
required for collecting top oil.
(f)
Cabling for fire detectors mounted on transformer /reactor top cover
(g) Inter cabling between signal box, control box and Fire Extinguishing Cubicle (FEC).
(h) Butterfly valves /Gate valves on oil drain pipe and nitrogen injection pipe which should
be able to withstand full vacuum.
(i)
Supports, signal box etc. which are to be painted with enameled paint.
(10) Technical Particulars
Fire extinction period from commencement of
nitrogen injection
: 30 s. (max.)
Total duration from activation of fire protection
system to complete cooling
: 30 minutes (Max.)
Fire detectors’ heat sensing temperature
: 141 .C
Heat sensing area per detector
: Up to a radius of 800 mm
Transformer Conservator Isolation valve setting
: 60 liter/ min (minimum)mm
Capacity of nitrogen cylinder
: 68 liter (maximum) water
capacity and shall hold
3
10 m (minimum)gas at
2
pressure of 150 kg/cm
o
SEC 04: Transformer
4/38
Power Supply
For control box
: 110 V DC
For fire extinguishing cubicle for lighting
: 240 V AC
(11) Mandatory Spare Parts
Cylinder filled with Nitrogen of required capacity per
substation
: 1 No.
Fire detectors per transformer
: 3 Nos.
Regulator assembly per substation
: 1 No.
(12) Tests
Reports of all type test conducted as per relevant IEC standards in respect of various bought
out items including test reports for degree of protection for FEC / control box / signal box shall
be submitted for approval.
The supplier shall demonstrate the functional test associated with the following:
-
Fire Extinguishing Cubicle, Control Box.
-
Fire Detector.
-
Transformer Conservator Isolation Valve
The performance test of the complete system shall be carried out after erection of the system
with transformer at site. Detailed layout drawings, equipment drawing along with 4 sets of
Operation and maintenance manual along with soft copies (in CDs) shall be submitted by the
Contractor along with the consignment.
4.16.3 Fire Wall
The fire wall having suitable height shall be installed between transformers toprevent the
health transformer from the spread fire.
The wall shall be constructed by thereinforced
concrete.
SEC 04: Transformer
4/39
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 5
PROTECTION, CONTROL, METERING AND SUBSTATION AUTOMATION
SECTION5
PROTECTION, CONTROL, METERING AND SUBSTATION AUTOMATION
TABLE OF CLAUSES
5.1GENERAL .......................................................................................................................... 5/3
5.2 FAULT CLEARANCE TIMES ............................................................................................... 5/3
5.3 ARRANGEMENT OF FACILITIES ...................................................................................... 5/4
5.4 MULTICORE CABLE DIAGRAMS ....................................................................................... 5/4
5.5 TEST AND EARTHING FACILITIES .................................................................................. 5/4
5.6 PROTECTION DEVICES ...................................................................................................... 5/5
5.7RELAYS
............................................................................................................................... 5/5
5.7.1 GENERAL ............................................................................................................................... 5/5
5.7.2 ELECTROMAGNETIC COMPATIBILITY ..................................................................................... 5/7
5.8 UNDER GROUND LINE PROTECTION ............................................................................. 5/8
5.8.1 230 KV UNDER GROUND LINE PROTECTION ......................................................................... 5/8
5.8.2 132 KV UNDER GROUND LINE PROTECTION ....................................................................... 5/13
5.8.3 DISTANCE AND DIRECTIONAL EARTH FAULT PROTECTION................................................. 5/14
5.9 BUSBAR PROTECTION .............................................................................................................
5.9.1 DOUBLE BUSBAR PROTECTION ........................................................................................... 5/14
5.9.2 CONDITION OF ACCEPTANCE OF BUSBAR PROTECTION SYSTEM SUBMITTED ON THE BASIS OF
CALCULATED PERFORMANCE ....................................................................................................... 5/15
5.10 CIRCUIT BREAKER FAILURE PROTECTION .............................................................. 5/16
5.11OVERCURRENT AND EARTH FAULT PROTECTION .................................................. 5/17
5.12COUPLING BAY PROTECTION ....................................................................................... 5/18
5.13TRANSFORMER PROTECTION ....................................................................................... 5/19
5.13.1 BIASED DIFFERENTIAL PROTECTION ................................................................................ 5/19
5.13.2 RESTRICTED OR BALANCED EARTH FAULT PROTECTION .................................................. 5/20
5.13.3 GAS PRESSURE (BUCHHOLZ) PROTECTION ....................................................................... 5/21
5.13.4 OIL AND/OR WINDING TEMPERATURE ............................................................................... 5/21
5.13.5 LOW OIL LEVEL AND PRESSURE RELIEF DEVICES ............................................................ 5/21
5.13.6 TAP CHANGER OIL SURGE................................................................................................. 5/22
5.13.7 TRIPPING RELAYS.............................................................................................................. 5/22
5.14D.C. AUXILIARY VOLTAGE OPERATING RANGE........................................................ 5/23
5.15TELEPROTECTION SIGNALLING .................................................................................. 5/23
5.16TRIPPING RELAYS ............................................................................................................ 5/23
SEC 05: Protection, Control SAS
5/1
5.17PROTECTION SETTINGS ................................................................................................. 5/23
5.18SUBSTATION AUTOMATION SYSTEM .......................................................................... 5/23
5.18.1 SCOPE OF SUPPLY ............................................................................................................. 5/23
5.18.2 COMPLIANCE WITH STANDARDS ........................................................................................ 5/24
5.18.3 DESIGN AND OPERATING REQUIREMENTS ........................................................................ 5/25
5.18.4 GENERAL SYSTEM DESIGN ................................................................................................ 5/28
5.18.5 FLEXIBILITY AND SCALABILITY ......................................................................................... 5/30
5.18.6 SYSTEM HARDWARE .......................................................................................................... 5/30
5.18.7 SOFTWARE STRUCTURE ..................................................................................................... 5/33
5.18.8 SYSTEM TESTING............................................................................................................... 5/34
5.18.9 SYSTEM FUNCTIONS .......................................................................................................... 5/35
5.19DIAGRAMS ......................................................................................................................... 5/44
5.20CURRENT TRANSFORMER CALCULATIONS .............................................................. 5/44
5.21 DIGITAL FAULT AND DISTURBANCE RECORDER [DFDR] .............. ...................... 5/44
SEC 05: Protection, Control SAS
5/2
SECTION 5
PROTECTION, CONTROL ,METERING AND SUBSTATION AUTOMATION
5.1
GENERAL
The protection and control facilities shall be suitable for the power system
arrangement as shown in the Drawings of this Technical Specifications.
From operational experience, including system stability, protection coordination,
integration with existing protection and control equipment,capitalizing of staff
experience and familiarization with equipment, protection settings calculation
mechanism and methodology of operation, standardization of operation
performance, facilities and spare requirements, the protection relays, control&
automation systems including complete panel are being rationalized to specific
types. The system operator is making every effort to avoid serious system maloperation and as such the types of relaying including complete panel to be
supplied for system expansion including this project shall comprise equipment
from the following manufacturers / countries of origin: 1) Alstom (France/UK),
2) ABB (Switzerland/Sweden), 3) Siemens (Germany) and 4) Schneider Electric
(France/UK). Acceptance of any other relays with similar characteristics will
have to undergo substantial field trials of at least one year to the satisfaction of
the chief engineer to ensure satisfactory operation.
The protection shall be sufficiently sensitive to cater for the minimum fault level
condition. This will be advised later. The protection shall also be suitable for a
system fault level equal to the switchgear rating as specified in clause 1.4.1 of
section-1 of this volume (2 of 2). All current transformer design shall be based on
these fault levels.
All relays shall operate correctly within system frequency limits of 47Hz to 51Hz.
5.2
FAULT CLEARANCE TIMES
230 kV, 132 kV and 33 kV systemsoverall fault clearance times (i.e. from fault
initiation to arc extinction) shall not exceed the following:
Type of Fault
Maximum Fault Clearance Time
Nominal system voltage between phases
kV
230
132
33
Substation and Transformer fault
msec
100
120
160
Up to 72% of the line length (ie. 90% msec
of a distance relay Zone 1 reach setting
of 80% of the line impedance)
100
120
160
Line fault
(a)
SEC 05: Protection, Control SAS
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(b)
72% to 100% of the line length
msec
where, (@) plus protection signalling time.
130
150
190
These requirements must be fulfilled under all system conditions including
maximum dc current offset and any time delay. Clearance within these times shall
be achieved for all types of faults except high resistance earth faults detected by
DEF protection or under circuit breaker failure conditions.
5.3
ARRANGEMENT OF FACILITIES
Control and relay equipment shall be mounted on panels and cubicles as specified
and shall be installed in permanent buildings on the substation sites. The order of
the panels shall follow the sequence shown on the drawings.
Control panels shall incorporate all necessary control and indication facilities for
the operation of the plant and equipment at the associated substation. In addition,
the plant may be remotely controlled and supervised from the National Load
Dispatch Centre (NLDC) in Dhaka.
The Gateway system for communication to the NLDC shall be supplied under
this contract including all necessary items like auxiliary switches, relays and
changeover switches, etc. Where specified for the mounting of, and connection
to, interposing relays and transducers, links shall be provided to enable
transducers to be isolated for test purpose and shortening facilities shall be
provided where transducers are used in the secondary of the current transformers.
All circuits provided under this contract whether or not they are subject to the
system control requirements at the present time, shall be designed and constructed
so that the standard facilities specified can be readily provided as required in the
future.
The employer will be responsible for carrying out system protection calculation
and determine relay setting value for the new substation including remote end
substation. The contractor shall review the protection setting calculation given by
the employer and shall be responsible for implementation of protection setting
that will be provided by employer including configuration, testing,
commissioning etc. The employer’s engineer shall witness the protection setting
& testing of the same. In case the proposed Protective relay is not suitable for the
proposed application the Contractor shall change to a suitable relay as
recommended by the manufacturer without any cost implications to the
Employer.
5.4
MULTICORE CABLE DIAGRAMS
This Contract includes the preparation of cabling schematic diagrams, showing
the approved routing of cores in the various cables, and detailed cable schedules
and connection diagrams for all the cables associated with each item of
equipment.
SEC 05: Protection, Control SAS
5/4
5.5
TEST AND EARTHING FACILITIES
Each control or relay panels shall be provided with a copper earth bar of not less
than 150 sq. mm Cross-section and arranged so that the bars of adjacent panels
can be joined together to form a common bus.
The common earthing busbar of control and relay panels shall be connected to the
main station earthing system via a copper earthing connection of not less than 150
sq. mm.
Software for testing the protection & control devices shall be included in the
scope of supply. In addition, for secondary injection testing of the protection &
control devices, provision shall be made in the panel for current & voltage
injection using standard test set and disconnecting type terminal blocks with
facility for short circuiting of current transformer secondary circuit etc. by means
of movement of links from their normal operating position, or any other testing
arrangement approved by the Employer.
5.6
PROTECTION DEVICES
Simplified arrangements of the main connections and protection for the various
items of plant are shown in the Drawings of this Technical Specifications.
Protection equipment shall be designed and applied to provide maximum
discrimination between faulty and healthy circuits. All equipment are to remain
inoperative during transient phenomena which may arise during switching or
other disturbances to the system.
Current transformers, where possible, are to be located so as to include the
associated circuit breaker within the protected zone and shall be located generally
as indicated on the schematic drawings included in this Specification.
Transformer Buchholz, winding temperature and tap changer protective devices
are to be supplied under this contract, and all necessary interposing relays,
tripping relays and cabling associated with these devices shall be supplied and
mounted under this Contract.
5.7
RELAYS
5.7.1
General
Relays shall conform to IEC 61850 standards, be of approved types complying
with IEC 60255 or BS 142 and 5992, parts 1, 2 and 3 as appropriate, fully
tropicalized, and shall have approved characteristics. Relays designed identical to
relays with a minimum of five years proven field experience will only be
accepted. Supply record of proposed relays shall be furnished for the last five
years. The Employer will reject any design he considers unsatisfactory or having
insufficient field experience. All the Protective relays shall be numerical type.
Numerical relays shall be configured in such a way that at least two(2) nos relays
SEC 05: Protection, Control SAS
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shall be provided for each feeder.
The protection relays, shall be located in conventional panels and shall be flush
mounted in dust and moisture proof cases and of the draw out type with rear
connections. The panel front side shall be covered by a transparent glass door.
Relays shall be of approved construction and shall be arranged so that
adjustments, testing and replacement can be effected with the minimum of time
and labour. Relays of the hand reset type shall be capable of being reset without
opening the case.
Electrically reset tripping relays shall be provided where necessitated by the
system of control, such as for those circuits subject to remote supervisory control.
Relay contacts shall be suitable for making and breaking the maximum currents
which they may be required to control in normal service but where contacts of the
protective relays are unable to deal directly with the tripping currents, approved
auxiliary contacts, relays or auxiliary switches shall be provided. In such cases
the number of auxiliary contacts or tripping relays operating in tandem shall be
kept to the minimum in order to achieve fast fault clearance times. Separate
contacts shall be provided for alarm and tripping functions. Relay contacts shall
make firmly without bounce and the whole of the relay mechanisms shall be as
far as possible unaffected by vibration or external magnetic fields.
Relays, where appropriate, shall be provided with LCD, LED or flag indicators,
phase coloured where applicable. LCD, LED or Flag indicators shall be of the
hand reset pattern and shall be capable of being reset without opening the case.
Where two or more phase elements are included in one case, separate indicators
shall be provided for each element.
All Relay settings shall be visible and readable without having to remove the
relay front cover. It shall not be possible to amend relay settings with the front
cover in place; other than over a serial link, if provided.
If a connector for local use is provided, this shall be accessible only after
removing the front cover. Where a port is provided for permanent connection to a
modem or other peripheral equipment, remote access shall be password protected.
Relays which rely for their operation on an external DC supply shall utilize for
this purpose the trip supply of the associated circuit-breaker trip coil. This supply
shall be monitored and an alarm provided in the event of failure.
Any auxiliary supplies needed shall be drawn from the main station batteries and
not from separate internal batteries in the protection equipment.
Relays, whether mounted in panels or not, shall be provided with clearly
inscribed labels describing their function and designation in addition to the
general purpose labels.
SEC 05: Protection, Control SAS
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Attention is practically drawn to the tropical climate and relay designs should be
entirely suitable for duty under full tropical conditions.
To minimize the effect of electrolysis, relay coils operating on DC shall be so
connected that the coils are not continuously energized from the positive pole of
the battery.
Relay shall be suitable for operation on 110 V nominal, 121 V float DC systems
without the use of voltage dropping resistors or diodes.
Numerical protection shall be designed in such a way that in case of a failure of
DC auxiliary infeed, the full information need to be maintained at least 24 hrs.
After a recovery of DC auxiliary infeed the last information and alarms will be
displayed and the alarm "failure of DC auxiliary infeed" released. The relay reset
shall not erase the relay memory.
The Numerical protection functions shall be in the form of software such that
additional or different functions, application specific logic, etc. can be readily
implemented without changes to the existing hardware. It shall be possible to
program/ parameterize by a portable computer (PC) all the numerical protective
relays and the entire relay operating and configuring software and the portable
computers and other accessory equipment needed to communicate with the relays
shall be provided.
All numerical relays shall be adequately protected against damage from incoming
surge and shall meet relevant IEC, BS and ANSI SWC test standards. Relays
shall utilize a DC-DC converter type regulated power supply to provide transient
surge isolation between the station battery and protection equipment. Each DC
supply shall be designed to protect it from high voltage and surge and provide
electrically isolated contacts for annunciation.
In addition to all equipment and components, the Contractor shall supply
documents and calculations to prove the correct functioning of the equipment and
he shall ensure and demonstrate that the setting range of relays and the operating
limits of all equipment are suitable for the intended applications.
5.7.2
Electromagnetic Compatibility
In certain cases, e.g.distance protection, current differential etc., electronic relays,
or devices utilizing microprocessors are specified and electromagnetic devices
will not be accepted.
Where such devices are required, they and the ancillary circuits connected to
them, such as power supplies, current and voltage transformer secondary’s, status,
tripping or alarm circuits shall be designed to ensure that they are compatible for
use in the hostile electrical environment found in an EHV substation.
Adequate steps, by means of suitable design, shall be taken to prevent
Electromagnetic Interference (EMI) (generated by sources such as circuit
SEC 05: Protection, Control SAS
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breakers, disconnecters, lightning, radio or radar emissions, switching contactors
in dc circuits, etc.) or Electrostatic Discharges (ESD) from affecting relay
performance or causing damage to components.
All relays offered must therefore have been type tested to meet the current
requirements of IEC 60255 with respect to High Frequency disturbance, Fast
Transients, Electrostatic Discharge, Radio Frequency Interference testing, etc.
SEC 05: Protection, Control SAS
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5.8
OVER HEAD LINE PROTECTION
5.8.1
230 kV & 132kV Overhead Line Protection
230kV Lines : N/A
132kV Lines :All 132kV overhead lines shall be protected by Distance relay as main
and
Directional Earth Fault relay as a backup under this Contract.
Only the backup protection can be incorporated in the bay control unit and not the main 1 and main 2
protection. Main protections shall be provided separately.
Both main protections and directional earth fault protection operating in conjunction with teleprotection channels over optical fibre or power line carrier circuits to form a permissive underreach
scheme of distance protection.
Each set of protection will be energised from separate current transformers and shall have facilities
for independently tripping duplicated circuit-breaker tripping coils and initiating auto-reclosing,
breaker failure protection, inter-tripping, alarms, fault location equipment, disturbance recorders
etc. The Contractor shall ensure that the relay contacts used for initiation of auto reclosing shall
have the same dwell time as the main tripping contacts to avoid any problems arising from contact
racing with the auto reclose relay.
Two sets of protection shall consist of different types of relays either from the same manufacturer
or from different manufacturers.Separate elements shall be provided for phase and earth fault
measurement. Separate elements shall also be provided for each zone. Phase and earth fault
compensation features shall be incorporated to ensure accurate distance measurement for all
types of fault and to allow for variation in the path of earth faults on the system.
5.8.1.1 Distance as Main-1 & Main-2 Protection and Directional Earth Fault Protection as
Backup
The main protection (First and Second main) shall be of numerical type and shall be providedby
distance relays for use with a signalling channel.
The relay scheme offered shall be suitable for use in the permissive under-reaching,permissive
overreaching, blocking and unblocking modes. All these options shall becontained and selectable in
the standard relay scheme. The relay should be applicableto all neutral ground possibilities and
should be suitable for the protection of long orshort over head lines or cables, double circuit lines,
heavily loaded lines, lines withweak infeeds etc.
The permissive overreach scheme shall operate in a permissive underreach/overreach transfer
tripping mode with underreaching zone I elements and overreaching zone 2 elements and suitable
logic to achieve fast tripping at the sending end in the event of a weak infeed at the receiving end.
The weak infeed logic shall comprise a zone 3 element set to look in the reverse direction, which
'echos' back the received signal to the sending end if the reversed zone 3 comparator does not
SEC 05: Protection, Control SAS
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operate.
To provide high speed tripping when a line terminal is open a 'signal echo feature' shall be provided,
which is initiated when either the feeder disconnector is open, or when the associated circuit
breakers are open.
The Zone 1 elements will normally be set to approximately 80 per cent of the line impedance. They
shall trip the local line circuit-breaker.
The Zone 2 elements will be set to over-reach the remote substation and in the case of permissive
over-reaching mode operate in conjunction with teleprotection signalling channels to form a
permissive over-reaching scheme. They shall also act as a back-up time delayed zone which trips the
local circuit-breaker. In the case of permissive under-reaching mode protection the overreaching
Zone 2 unit will be used as the permissive element to permit instantaneous tripping of the local
circuit.
The Zone 3 elements shall provide a further time delayed back-up zone.
Distance protection back-up zones shall also trip the remote end circuit breaker(s) via a direct
intertripping channel.
Partially cross polarised mho or polygonal impedance characteristics relays are preferred for Zones 1
and 2 for 3-phase and 2-phase faults but other characteristics will be considered. Quadrilateral
characteristics with adaptive reactance measurement to avoid overreach or underreach for resistive
faults with pre fault load are preferred for earth faults. The relays shall operate for faults in the
direction of the protected line only. Under no circumstances shall they operate for reverse faults even
when the voltage supplied to the relay falls to zero on all three phases nor shall they operate due to
the transient response of the capacitive voltage transformers following reverse close-up faults.
Details of methods used for polarising the relays to deal with faults close to the relaying point shall be
provided. Zone 3 shall be capable of being set as either directional or non-directional and shall be
capable of being independently off set in both directions.
The reach of each zone and reverse element shall be individually adjustable by means of a multi-tap
voltage transformer or other approved method. The characteristic angle shall be adjustable between
approximately 40 and 80 degrees.
Where used in a permissive overreach transfer tripping scheme with weak infeed tripping the zone 3
unit may be set looking in the reverse direction. The reverse looking impedance/directional elements
shall detect all reverse faults capable of being detected by the Zone 2 relay at the remote substation.
Bidders shall explain how this is achieved.
Single pole tripping and auto-reclosing are being employed and the auto-reclosing scheme
requirements are given in Section 5.11.The distance protection shall be suitable for such a scheme
and the Contractor shall substantiate by calculation or other means that phase selective tripping will
be achieved under the system conditions anticipated in the daily operation.
The Contractor may request whatever information he requires for carrying out the necessary
calculations.
SEC 05: Protection, Control SAS
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Auto reclosing shall be capable of being blocked for
i)
any three phase fault
ii)
any Zone 2 or Zone 3 time delayed trip
iii) carrier channel out of service
iv) DEF aided trip
v)
DEF back up time delayed trip
vi) Switch on to fault.
The necessary circuitry shall be incorporated to inhibit the Zone 1 and Zone 2 phase fault elements
when necessary during single phase to earth faults and during the single phase autoreclose dead
time. These features shall be selectable by links or switches. Provision shall also be made to ensure
that the earth fault elements reset during the single phase dead time.
The protection sensitivity shall be shown to be adequate for the minimum fault level conditions.
These will be advised to the Contractor at a later stage.
Where fault resistance may be significant, the Contractor shall illustrate that the distance protection
can cover such values taking fault current distribution and load conditions into account.
The operating time of each distance protection zone shall be substantially independent of fault
current magnitude. The operating times shall be stated in the Schedule of Particulars and, in addition,
curves shall be provided showing the effect of line and source impedance, fault position and
operating current.
Under no circumstances shall any line protection operate because of normal system switching
including de-energisation of the line.
A feature shall be incorporated to ensure instantaneous tripping in the event that the circuit-breaker
is closed onto a fault on a previously de-energised line.
Distance protection back-up Zone 2 and Zone 3 time delay setting ranges shall be 0.2 to 1.0 seconds
and 0.5 to 3.0 seconds respectively.
A carrier receive signal extension timer with a delay on reset of 100 msecs shall be provided to ensure
that relays at both ends of a parallel feeder circuit have sufficient time to trip for faults occurring in
the end zones of the protected line.
A monitoring system shall be provided to supervise the voltage transformer supply to each set of
distance protection. In the event of loss of one, two or three phases, the monitoring system shall
inhibit relay operation and initiate an alarm. The VT supervision unit associated with the distance
relay shall also inhibit the DEF protection in the event of VT fuse failure.
All relays shall incorporate indicators to show the relay tripped, zone indication and the phase or
phases faulted. Indication must not be lost in the event of a supply failure.
Directional earth fault protection operating in a permissive overreach scheme shall be provided to
cater for high resistance faults which cannot be detected by the distance protection. The same
teleprotection signalling channel shall be used for the directional earth fault scheme and the distance
protection scheme. An echo feature shall be included with the DEF Scheme and shall be subject to
SEC 05: Protection, Control SAS
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approval by the Engineer.
The directional relays shall be dual polarised i.e. polarised with zero sequence voltage and current.
The relay sensitivity shall be adjustable between approximately 5 and 10% of rated current. A relay
characteristic angle of 60 degrees is preferred but alternative angles will be considered. It is
appreciated that because the 230kV system zero sequence source is an auto transformer with a delta
tertiary winding, that current polarising of a dual polarised relay is unreliable without careful analysis.
The contractor shall be responsible for determining whether such a current signal can be taken from
the auto transformer neutral and safely used for polarising the relay within three months of being
advised of all transformer impedance parameters.
The directional earth fault protection shall initiate three pole tripping. It must therefore include a
short time delay to permit single pole tripping by the distance protection. Initiation of three pole
reclosing following operation of a DEF aided trip shall be selectable by means of a switch.
Directional earth fault relays shall incorporate a back-up stage in addition to the aided tripping unit.
The time delay range shall be 0.2 to 5.0 seconds or inverse time delayed with a characteristic to IEC
60255.
Neither the distance protection scheme nor the directional earth fault scheme shall mal-operate due
to fault current reversal during sequential clearance of a fault on the parallel circuit.
The effect of zero sequence mutual coupling between the double circuit lines on the protection shall
be described, together with any measures considered necessary to overcome this effect.
The distance protection time delayed back-up Zones 2 and 3 and the directional earth fault back-up
stage shall intertrip the remote station circuit-breakers over direct intertripping channels.
Auto reclosing shall not be initiated on receipt of direct intertripping signal. Direct intertripping shall
also be initiated in the event of a 3 phase fault in any zone, or following a switch on to fault trip.
Distance relays shall be supplemented by power swing blocking relays. Power swing blocking relays
shall be compatible with their appropriate distance relays, and for distance relays having offset mho
zone 3 characteristics or starters shall comprise an offset mho characteristic which encompasses and
is concentric with the distance relay impedance starter or zone 3 characteristic. Similarly where it is
possible to shape the zone 3 or starter characteristic the power swing blocking relay characteristic
shall also be capable of similar shaping. Where zone 3 is set reverse looking the power swing blocking
characteristic shall be set such that it encompasses the forward looking zone 2 characteristic.
Facilities shall be provided to block zones 1, 2 and 3 of the distance relay from the power swing
blocking logic as required.
Blocking logic shall be derived by determining the time taken for the apparent impedance of the
power swing locus to pass from the characteristic of the power swing relay to the appropriate
distance relay characteristic. Blocking shall not take place until the apparent impedance has passed
through the two power swing characteristics and the set time delay has expired.
The associated time delay relay shall have a setting range of 50-250 ms.
Relays shall be of numerical or static design. Electromechanical relays will not be accepted. The
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Numerical relays shall be design with 16 bit Analogue to Digital converters, powerful Digital signal
processors, CPU etc. The relay should have continuous self supervision and diagnosis. A local display
unit shall be provided on the front of the relay for measure and display, Distance to fault indication,
diagnostics, etc and also for acknowledging and resetting of latched outputs. The required software
for setting and configuring the relay shall be provided with the relay and this Man Machine
Communication (MMC) shall be user friendly and should not require any special programming
knowledge. It should be possible to do the settings off line and load the settings on to the relay with a
standard portable PC with a fibre optic connection. A separate communication port shall be provided
so that the distance relays can in future communicate with the Station monitoring system as well as
easily be integrated into Station Control Systems. A PC with a Man Machine Communication (MMC)
software for setting of the relay shall be included in the scope of supply.
Reset times shall be low to ensure the associated distance relay reverts to its normal role as soon as
possible following a power swing.
Power swing blocking shall be inhibited during the single pole dead time of an auto reclose cycle so
that if a power swing develops during this period the distance protection can give an immediate three
phase trip. The bidder shall advise whether it is possible to extend the inhibition of the power swing
blocking to cover a period immediately following auto reclosing so that if a power swing develops on
reclosing onto a permanent fault a 3 phase trip would be permitted. The bidder shall also advise
whether power swing blocking can be inhibited if an earth fault occurs during a power swing.
If the associated VT supplies are lost due to VT fuse failure the power swing blocking relay shall not
operate.
Where protection is supplied from multi-ratio current transformers, the lowest ratio will be used for
the initial system configuration, when fault levels are low. The working ratio will be increased when
the system expands and the fault levels and load transfers increase.
5.8.1.2 Differential asMain-1 & Main-2 protection and Directional Earth Fault Protection as
Backup
The protection shall be of numerical type line differential relay and shall be suitable forshort
underground or over head line protection (single or double circuit) in solidly or low
impedancegrounded systems.
The relay shall incorporate a facility to compensate for different CT ratios at each lineterminal.
A tripping signal for a fault shall be given within 30 ms of fault occurrence (includingmain tripping
relay).
The differential protection shall measure the currents of three phases independentlyand the tripping
shall take place should the comparison of the values in both theterminal stations result in a
differential current above a set level. The relay shall incorporate methods for ensuring protection
stability for external faults with allowancefor CT transformation errors. The minimum CT
requirements for the protection must beclearly stated.
The protection shall offer phase-selective tripping, if required.
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For digital communication between relays at each line terminal, the protection shall besuitable for
direct interfacing to the available communication link according to theparticular application. This may
be a pair dedicated optical fibres, or a digital interfacecard of a multiplexed communications link.
Where the multiplexer forms part of anoverall communications system, the relays shall incorporate
the necessary algorithmsto ensure stability with load current during communications path routeswitching.
Upon detection of a communications channel failure and following a time delay ofless than 10
seconds, an alarm shall be given. In the event of signalling channel failurethe protection must not trip
due to load or emergency load currents.
The protection system shall incorporate at least one zone of directional underimpedance protection,
to provide time-delayed remote back-up tripping in the even of afault in an adjacent remote circuit
not being cleared by its main protection. Thisprotection function shall be blocked in the event of VT
signal failure.
The protection system shall offer standby directional protection elements that canautomatically or
manually (as selected) be brought into service in the event of datacommunications link failure
between the relay terminals. The alternative protectionshall, preferably be one zone of high-speed
underreaching distance protection and onezone of time-delayed overreaching distance protection.
In addition to the tripping contacts the protection shall provide all necessary contactsfor initiating
phase-selective auto re-closing, breaker failure protection, disturbancerecorder, signalling and
alarms.
For overhead lines, the relay shall be compatible with the external single and threephase autoreclose
system which is to be common for the Main-1 and Main-2protection, as detailed in Section 5.11.
The protection system shall include a secure integral inter-tripping facility, which canbe used as a
secondary inter-tripping path by external breaker fail protection.
The relay shall be equipped with self-supervision of both its software and hardware(including VT
signal supervision). Detection of a failure shall result in the affectedpart(s) of the protection system
being blocked, so that no incorrect tripping will occur.
In the event of a relay failure an alarm contact must operate and the nature of thefailure should be
indicated where possible.
The trip output contacts of the relay must either be suitable for switching the breakertrip coil currents
directly, or an interposing trip relay with heavy duty contacts must beprovided. In the event of
breaker failure, where the circuit breaker auxiliary contact maynot interrupt the trip coil current, the
trip contacts within the differential relay should notbe damaged if the relay resets following breaker
fail protection clearance.
5.8.2
Coupling Bay Protection
The Coupler bay shall be provided with overcurrent instantaneous trip relay protection and
overcurrent time delay relay protection and instantaneous trip relay protection. Relays shall comply
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with the requirements of clause 5.7.
In case of main & transfer bus arrangement all trip-signal of line and transformer feeder protection
shall be transferred to the coupling breaker in case the feeder breaker is bypassed and the feeder is
protected by the coupling-bay circuit breaker. This shall be provided by auxiliary relay, not by auxiliary
contacts of the circuit breaker by-pass isolator.
5.9.1
BUSBAR PROTECTION
The busbar protection (doublescheme) shall be low impedance type numerical relay The protection
shall be extensible to cover the final substation arrangements and Bidders shall state what extra
material is required.
The busbar protection shall have the following features:
(a) Two independent measurement & tripping criteria. One based on stabilized current differential
algorithm and the other on directional current comparison and shall be capable of detecting three
phase, phase-phase and phase to earth faults, under all system generation plant conditions. They
shall meet the fault clearance time of 100ms under all conditions.
(b) Two independent hand or electrically reset busbar protection trip relays shall be associated with
each circuit-breaker. These trip relays may also be employed for circuit breaker failure.
Operation of either of these relays shall block closing of the associated circuit breaker.
(c) Each trip relay shall trip the circuit-breaker via both trip coils. Both relays on the 230kV or
132 kV transformer circuits shall trip the associated circuit-breakers.
(d) The operating time of the measuring relays shall not exceed 30 msecs at five times the relay
current setting.
The busbar protection will be supplied from multi-ratio current transformers. The working ratio will
be selected on the basis of maximum load transfer in the same manner as the line current
transformer ratios.
The overall fault setting shall be between 10% and 30% of the minimum fault current available for any
type of fault, unless otherwise specified. The minimum fault current for busbar faults will be advised
at a later stage.
The rated stability limit of the protection shall not be less than the switchgear short circuit rating.
Automatic and continuous supervision of current transformer circuits shall be provided to give an
alarm when the out-of-balance current reaches an undesirable value.
Operation of current
transformer supervision equipment should take the defective protection zone out-of-service.
The Contract shall include for all necessary current transformers, relay panels, marshalling boxes,
isolating and shorting links, etc. A lockable Busbar protection ON/OFF switch shall be provided.
Current transformer secondary bus wiring should be suitably dimensioned to reduce current
transformer burdens to a minimum.
Suitable voltage limiting devices shall be provided as necessary, including across the unused part of
the CT secondary when tapings are employed.
Full details of the scheme offered, together with performance figures for stability and sensitivity, shall
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be provided in accordance with Clause 5.9.2.
The numerical busbar protection shall be multi processor in structure, with extensive self supervision,
16 bit analogue to digital converters, together with appropriate algorithms to provide phase
segregated measuring principles and multi criteria evaluations before initialisation of trip commands.
The busbar protection shall be of decentralised type and the bay units shall be fixed as close to the
CT’ s as possible reducing the copper wiring to a bare minimum and thereby also reducing the CT
burden and CT dimension.
If the intercommunication between the bay unit and central unit by fibre optic cables, the required
fibre optic cable and all necessary items shall be supplied, connected and commissioned by the
contractor.
5.9.2
Conditions of Acceptance of BusbarProtection Systems Submitted on the Basis of
CalculatedPerformance
The Engineer is prepared to accept Calculated Performance data for differential busbar protection
systems in lieu of heavy current tests, subject to the following:
i)
The rated stability limit shall be no less than the three phase symmetrical breaking capacity of the
associated switchgear.
ii)
The overall fault setting for any type of fault shall be between 10% and 30% of the minimum fault
current available. The minimum fault current available for a busbar fault will be advised later.
iii) Current transformer knee point voltages shall not be less than twice the relay circuit setting
voltage.
iv) The maximum peak voltage across current transformer secondary wiring shall not exceed 3kV
under maximum internal fault conditions.
v)
Associated current transformers shall be 5P20, low reactance type. Split core type current
transformers will not be accepted.
vi) The contractor shall submit for the Engineers approval a design report detailing the protected
equipment, design parameters of associated current transformers, details of connections and
burdens between current transformers and relays, details of the relay circuits and performance
calculations.
5.10
CIRCUIT BREAKER FAILURE PROTECTION
Breaker failure protection shall be fitted to all 230kV & 132kVcircuit breakers.The breaker failure
protection on a circuit-breaker shall be initiated by all the other protection devices which normally
initiate tripping of that breaker including the receipt of a direct intertripping signal from a remote line
end. In the event of the circuit-breaker failing to open within a pre-selected time, the breaker failure
protection shall initiate tripping of all adjacent circuit-breakers. It shall also incorporate provision for
initiating tripping of any remote infeeds, via direct intertripping channels over optical fibre
communication link or power line carrier circuits.
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The position of each circuit-breaker shall be monitored by a current check relays fed from the
protection current transformers as shown on the drawings. The relay outputs shall be connected in
series in a "two out of two" arrangement. The relays shall have an operating time of approximately
10msec. and a consistent reset time of less than 15msec. The relays shall be capable of remaining in
the operated position continuously and of carrying twice the circuit rated current continuously.
The scheme provided shall be suitable for use in a single pole and three pole tripping and auto
reclosing schemes as appropriate.
The operating time from initiation to back tripping output shall be selected by means of duplicated
timers with a setting range of 50-500 msecs. The two timers per circuit breaker in the case of the 230
kV scheme shall be connected in series in a two-out-two basis and shall energise both trip coils of all
adjacent circuit breakers via two back tripping circuits from separate d.c. supplies.
The timers shall be of a modern design to minimise overtravel. With the approval of the Engineer the
busbar protection trip circuits may be employed for circuit breaker fail back tripping.
In the event that a circuit breaker is unable to trip due to low gas pressure, low hydraulic oil pressure
etc the associated alarm shall be arranged to by-pass the breaker fail time delay. The breaker fail
relay/scheme shall be designed to accept this input.
Operation of the breaker fail protection shall block manual and automatic reclosure of the associated
circuit breaker. Breaker failure protections inbuilt in distance / transformer relays will not be
accepted.
5.11
AUTO RECLOSING SCHEME
Three pole and/or single pole, single shot repetitive auto-reclosing equipment, shall be provided for
the overhead line circuit-breakers.
Reclosure shall be initiated following tripping by either main protection operating in Zone 1 or in
conjunction with a teleprotection receive signal. Selection facilities shall also be provided to enable or
block three pole delayed auto-reclosing following operation of the directional earth fault protection
aided trip output. Reclosure shall not be initiated in the event of a three phase fault, nor any type of
fault in the second or third back-up zones, nor when a direct intertripping signal is received, nor when
the circuit-breaker is closed onto a fault on a previously de-energised line, nor when the DEF back-up
protection operates nor if the carrier channel is out of service.
The following modes of operation shall be selectable by means of a switch or switches or
programmable.
(a)
Single pole, high speed, auto-reclose: Auto-reclosure shall only be initiated in the eventof a
single phase to earth fault. All other types of faults shall result in three phasetripping without
auto-reclosing.
(b)
Three pole delayed reclosing: Delaying reclosing shall only be initiated in the event of asingle
phase or two phase fault. Three phase faults shall result in tripping without auto-reclosing.
(c) Single pole, high speed and/or three phase delayed, auto-reclosing as appropriate.
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Single pole, high speed auto-reclosing shall be initiated only in the event of a single phase-earth
fault and delayed reclosing initiated in the event of a two phase fault. Three phase tripping without
re-closing shall take place for three phase faults.
(d)
No auto reclosing: Three phase tripping without auto-reclose shall take place for any type of
fault.
If a second earth fault occurs during the single pole auto-reclose dead time, and the selector switch is
in the single and/or three pole reclosing mode three phase tripping with subsequent delayed three
pole auto-reclose shall take place. If the auto-reclose selector switch is in the single pole reclose
mode, three phase tripping with lockout should follow. Any auxiliary relays required to meet this logic
shall be deemed to be included.
The high speed and delayed reclosing dead times have to be co-ordinated with the equipment being
provided at the remote substation. Tentative ranges are, as follows:
High speed single pole reclose dead time:
0.3 to 3 seconds.
Delayed three pole reclose dead time:
3 to 30 seconds.
Bidders shall state available ranges.
The reclaim time i.e. the time period following the automatic reclosing of the circuit-breaker, during
which any further fault results in three phase tripping and lockout, shall be chosen to match the duty
cycle of the circuit-breakers, assuming the shortest available dead time is chosen. The reclaim time
shall not, however, be less than five seconds, and the reclaim timer range shall extend to 180
seconds. (The reclaim time commences at the instant the reclose command is given to the
circuit-breaker and, therefore, includes the circuit-breaker closing time).
The closing command shall be limited to two seconds, after which time the reclosing equipment shall
be automatically reset without resetting the reclaim timer. The reclosing equipment shall also reset if
dead line check or synchronism check conditions are not satisfied within a predetermined time of the
check relays being energised.
A counter shall be provided to record the number of reclosures and lockout after a pre-selected
number of reclosures has been reached.
The rated duty cycle of the circuit breaker as defined in IEC 60056 (and subsequent amendments)
states that following an initial trip and auto reclosure a further reclosure is not permitted for a further
3 mins.
Reclosing schemes shall include voltage monitoring and check synchronising relays as appropriate.
Dead linecheck relays shall monitor the condition of the line and busbar and permit three pole
reclosing only when the line is de-energised and the busbar is energised. The line is considered to be
de-energised when the voltage is less than twenty percent of rated voltage, and the busbar is
considered to be energised when the voltage is greater than eighty percent of rated voltage.
(A signal shall be provided from the dead line check relays for interlocking of the line earth switches
to prevent the switches being closed onto a live line).
When a voltage is present on both sides of a circuit breaker, the synchronism check relay shall
SEC 05: Protection, Control SAS
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monitor the magnitudes of the two voltages across the open circuit-breaker, and the phase angle and
slip frequency between these voltages. Closing shall only be permitted when these are within
prescribed limits.
Check synchronising relays shall comply with the requirements of Clause 5.24.1.The same relays may
be used as for manual closing.
5.12
OVERCURRENT AND EARTH FAULT PROTECTION
The overcurrent and earth fault relays shall be fully Numerical and have multi characteristics (inverse,
very inverse, extremely inverse) to IEC 60255.
Overcurrent relays shall have a current setting range from at least 50% - 200% in 25% setting steps.
Earth fault relays shall have a current setting range from at least 20% - 80% in 10% setting steps.
Time multiplier settings shall be continuously adjustable from 0 to 1 or, as an alternative in steps of
0.025 from 0.05 to 1.0.
In the case of transformer circuits relays shall be provided with high set instantaneous units which
can be set to 1.25 times the fault current in the HV winding for a fault on the LV terminals computed
using the transformer minimum impedance and assuming negligible source impedance. The
instantaneous unit shall have a low transient overreach (less than 5% for system X/R ratio of 10) and
an operating time of less than 40 msec at two times the current setting.
In the case of underground line circuits relays should have a reset ratio greater than 95% to enable
settings to be made which are close to the circuit emergency rating. The relay contacts must close at
a current equivalent to 110% of the setting and relay overshoot must not exceed 50 msecs.
Overcurrent and earth fault relays shall trip via the CB duplicate trip coils and initiate duplicated
direct intertripping to the remote line end CB.
Relays shall be thermally rated such that the operating time of the relay at the highest practical
current levels on any combination of current and time multiplier settings shall not exceed the thermal
withstand time of the relay. The contractor shall provide copies of type test reports to show that this
requirement has been met.
Directional back up overcurrent and earth fault relays shall be provided for underground Cable
feeders and the directional elements shall be voltage polarised.
Directional units for directional overcurrent protection shall be quadrature connected with a relay
characteristic angle setting of 30° or 45° current leading voltage.
Directional units for directional earth fault back up protection shall employ residual voltage quantities
and the relay characteristic angle be variable 0°, 45° and 60°, current lag.
The nominal operating boundary shall be ±90° from the relay characteristic angle and the operating
time of the directional unit shall not exceed 20 ms at the relay characteristic angle.
The relay shall be capable of operating correctly when both the operating current and polarising
voltage quantities are 1% of rated values at an angle equal to the relay characteristic angle.
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The residual polarising voltage for earth faults may reach 190.5 volts and therefore it should
withstand this value continuously. The continuous withstand current should be no less than twice
rated current.
5.13
TRANSFORMER PROTECTION
5.13.1 Biased Differential Protection
The transformer differential protection shall be fully numerical design with 16 bit Analogue to Digital
converters, powerful Digital signal processors, CPU etc. The relay should have continuous self
supervision and diagnosis. A local display unit shall be provided on the front of the relay for measure
and display, Trip indications, diagnostics, etc and also for acknowledging and resetting of latched
outputs. The required software for setting and configuring the relay shall be provided with the relay
and this Human Machine Interface (HMI ) shall be user friendly and should not require any special
programming knowledge. It should be possible to do the settings off line and load the settings on to
the relay with a standard portable PC with a fibre optic connection.
Overall differential protection shall be of the biased differential type and capable of detecting phase
and earth faults.
Separate facilities shall be provided to enable bias and operating settings to be adjusted. The
minimum operating setting shall not be greater than 20 per cent of the rated full load current of the
transformer.
The protection shall be designed to ensure stability on any transformer tap position under maximum
through fault conditions with maximum d.c. offset. An infinite source is to be assumed and the
through fault current calculated using the transformer impedance only.
Correction for matching transformer vector groups and main CT ratio’s for Transformer Differential
protection shall be performed within the relay without the use of external interposing-transformer.
The relays shall have magnetising inrush current restraint of the second harmonic or other approved
means. All necessary interposing current transformers shall be provided under the contract.
Where specified in the drawings two separatebiased transformer differential protection relays shall
be provided for each transformer.
5.13.2 Restricted or Balanced Earth Fault Protection
Where specified, or shown on drawings, transformer windings and connections shall be protected by
restricted earth fault protection. Delta connected windings shall be protected by balanced earth fault
protection. Relays shall be of identical numerical design as the main protection and of the low
impedance type with necessary protection against over voltages. For reliability reasons the Restricted
earth fault relay shall be separate from the main-1 transformer differential relay, but incase of two
bised differential relay the Restricted earth fault relay can be incorporated in main-2 differential
relay.
Relays shall have maximum sensitivity and minimum operating times consistent with stability for
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faults outside the protected zone and on magnetising inrush surges.
The rated stability limit shall not be less than the maximum current available for an external fault.
This shall be taken as 16 times the rated current of the protected winding of the power transformer,
or any other value agreed by the Engineer.
For the purpose of calculations it shall be assumed that any neutral earthing impedance is short
circuited.
The Engineer is prepared to accept calculated performance for instantaneous high impedance
restricted earth fault protection in lieu of heavy current tests, subject to the conditions in Clause 5.9.2
except:
i) The rated stability limit shall be as specified above.
ii) The fault setting shall be as specified below.
(a) When the transformer winding is connected to a solidly earthed power system, the
fault setting shall be between 10% and 60% of the rated current of the winding.
When the transformer winding has more than one rating, the setting shall be based
on the lower rating.
(b) When the protected transformer is not connected to a solidly earthed power system
the fault setting shall be between 10% and 25% of the minimum current available
for an earth fault at the transformer terminals.
5.13.3 230/132kV Transformer Back-up Overcurrent Protection
Three pole inverse time back up overcurrent and earth fault protection shall be provided as shown on
the drawings. This shall comply generally with Clause 5.12 but in addition the overcurrent elements
shall also be a two stage device. Stage 1 shall be arranged to trip the 132kV circuit breaker and stage
2, the 230kV circuit breaker. Stage 1 will comprise the inverse time unit and stage 2 will comprise an
additional definite time unit with a setting range of 50 msec - 5 secs.
5.13.4 Gas Pressure (Buchholz) Protection
Power transformers and earthing transformers shall be fitted with Buchholz devices under this
contract. The Buchholz device will be of the two element type giving operation under gassing and
under surge conditions.
All necessary flag indication, tripping relays and alarm relays associated with this protection shall be
provided, mounted and connected under this Contract.
5.13.5 Oil and/or Winding Temperature
Transformers will be provided with oil and/or winding temperature protection under this contract.
These will be of the two stage type with adjustable settings giving alarm and trip facilities.
All necessary flag indication, tripping relays and alarm relays associated with this protection shall be
supplied and connected under this Contract.
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5.13.6 Low Oil Level and Pressure Relief Devices
Transformers shall be provided with low oil level with contacts for the purpose of providing remote
alarm. Transformers shall also be provided with a pressure relief device with contacts for purposes of
remote alarm and trip function.
The alarm relays associated with these devices shall be supplied and connected under this Contract.
5.13.7 Tap Changer Oil Surge
Transformers will be provided with an oil surge or pressure operated device having contacts for
purposes of remote alarm and trip.
A relay associated with this device shall be supplied and connected under this Contract.
All necessary flag indication, tripping and alarm relays associated with tap change oil surge shall be
provided.
5.13.8 Standby Earth Fault Protection
Standby earth fault protection shall be provided for all earthing transformers/resistors, fed from a
current transformer in the transformer/resistor neutral connection.
The operating current shall be adjustable between 10 and 40 per cent of the resistor value. The time
delay shall be adjustable between 1 and 10 secs. As an alternative to a definite time relay, a long
inverse time relay may be offered.
5.13.9 Tripping Relays
All tripping relays, where specified shall be of the heavy duty type suitable for panel mounting. The
trip relays of the offered numerical protections shall be directly capable of tripping the breaker coils.
It shall not be required to add additional trip relays
Trip relay contacts shall be suitably rated to satisfactorily perform their required duty and relay
operating time shall not exceed 10 ms from initiation of trip relay operating coil to contact close.
Where specified latching type relays shall have hand or electrically reset contacts and hand reset flag
indicators. Resetting of the flag indicator and the contacts shall be possible without having to open
the relay case.
Tripping relays shall operate when the supply voltage is reduced to not higher than 30% of nominal
battery voltage. It shall not operate for wiring leakage currents and discharge of wiring capacitance
230kV and 132 kV circuit breakers are equipped with two trip coils. One tripping relay shall initiate
tripping via one trip coil and the other tripping relay via the second trip coil.
5.14
DC AUXILIARY VOLTAGE OPERATING RANGE
DC operatedrelays, coils, elements, etc. will be operated from a 110V rated d.c.
battery, which under float charging conditions operates at about 125V d.c.
operated relays coils elements etc. shall be suitable for operation over a voltage
range of 66V to 143V. ie. 110 - 40% + 20%.
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5.15
TELEPROTECTION SIGNALLING
Details of protection initiation and various permissive and direct intertripping
signals are indicated as follows:
Proposed Fiber Optic Multiplexer equipment system layoutDrawing of this
Technical Specifications.
5.16
TRIPPING RELAYS
All tripping relays, where specified shall be of the high speed, (less than 10ms),
high burden, heavy duty (greater than 150W) type suitable for panel mounting.
Relays shall comply withthe requirements of Clause 5.13.9.
5.17
PROTECTION SETTINGS
Relay settings with calculation for all unit type protective schemes and shall be
submitted to the Employer prior to commissioning of any plant for approval.
Settings shall also be provided for those relays and other equipment provided
under this Section of the Contract which do not require an intimate knowledge of
existing relay settings e.g. circuit-breaker fail relays.Detailed calculations shall be
provided supporting all recommended settings.
Any additional information needed by Contractors should be requested.
5.18
SUBSTATION AUTOMATION SYSTEM
5.18.1
Scope of Supply
This specification covers the design, manufacture, inspection, testing at the
manufacturer’s works, erection and commissioning of a Substation Automation
System, as shown in Drawing of this Technical Specifications& described in the
following sections, to control and operate the substation.
This describes the facilities required to provide the control of plant and system
within a substation and outlines the facilities to be provided on site, interface
requirements and performance criteria.
The Substation Automation System (SA) shall comprise full station and bay
protection as well as control, monitoring and communication functions, and
provides all functions required for the safe and reliable operation based on IEC
61850 standards supplied in cubicles. It shall enable local station control via PC
by means of a human machine interface (HMI) and control software package and
perform the necessary system control and data acquisition functions. It shall
include communication gateway to NLDC, inter-bay-bus, intelligent electronic
devices (IED) for bay control and protection as shown in the enclosed general
system architecture drawing.
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The communication gateway shall secure control from and information flow to
remote network control centers. The inter-bay bus shall provide independent
station-to-bay and bay-to-bay data exchange. The bay level intelligent electronic
devices (IED) for protection and control shall be directly connected to the
instrument transformer and trip/close coils in the switchgear without any
interposing equipment and perform control, protection, and monitoring functions
subject to a detail proposal approved by the Employer.
The contractor will have option to choose different type of communication
network for bay level and process level based on IEC 61850. But network
topology and access mode shall be clearly indicated. The availability shall be
maintained with suitable topology of ring, star or bus. The physical medium of
those shall be glass fibre optics.
The IED’s for protection and control functions shall maintain high availability
and reliability together with bay independence through extensive self-supervision
and state-of-the-art technology. All IED’s shall be directly connected to the IEC
61850 bus and shall use only IEC 61850 protocol for communication. No
proprietary protocols shall be used.
The system shall be capable of having its computing power increased in the
future by the addition of additional computing systems.
The system design life shall be not less than 20 years.
The capacity of the SA system shall be sufficient for the ultimate development of
the substation as set out in the project requirements.
The SA supplier shall demonstrate that the system proposed has been designed,
installed and commissioned in accordance with IEC 61850 standards and shall
provide evidence of satisfactory service experience during the past 5 years.
5.18.2 Compliance with standards
For design and type testing of the protection and control equipment, the following
standards shall be applicable:
5.18.2.1
General List of Specifications
· IEC 60255: Electrical Relays
· IEC 60038: IEC Standard voltages
· IEC 68068: Environmental testing
· IEC 60664: Insulation co-ordination for equipment within low-voltage
systems
· IEC61850: Standard for Substation integrated protection and control data
communication
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5.18.2.2
Detailed List of Specifications
· IEC 255-6: Measuring relays and protection equipment
· IEC 255-7: Test and measurement procedures for electromechanical all-ornothing relays
· IEC 68-2-3: Test Ca: Damp heat steady state
· IEC 68-2-30: Test Db and guidance: Damp heat, cyclic
· IEC 255-5: Insulation tests for electrical relays
· IEC 255-22: Electrical disturbance tests for measuring relays and protection
equipment:
· IEC 255-22-1: 1 MHz burst disturbance test
· IEC 255-22-2: Electrostatic discharge test
· IEC 255-22-3: Radiated electromagnetic field disturbance test
· IEC 255-22-4: Fast transient disturbance test
· IEC 255-11: Interruptions to and alternating component (ripple) in D.C.
auxiliary energising quantity to measuring relays
· IEC 255-6: Measuring relays and protection equipment
· IEC 255-21: Vibration, shock, bump and seismic tests on measuring relays and
protection equipment
· IEC 255-21-1: Vibration tests(sinusoidal)
· IEC 255-21-2: Shock and bump tests
· IEC 255-21-3: Seismic tests
· IEC 255-0-20: Contact performance of electrical relays
· IEC 870-3/class 2: Digital I/O, Analogue I/O dielectric tests
· IEC 801-5/class 3: Digital I/O Surge withstand test
· IEC 870-3/class2: Radio interference test
· IEC 801-4/4: Transient fast burst test
· IEC 801-2/4: Static discharge
· IEC 801-3/3: Electromagnetic fields
5.18.3 Design and Operating Requirements
5.18.3.1General
The SA shall be suitable for operation and monitoring of the complete substation
including future extensions. The supplier shall provide a high quality SCD file
(System Configuration Description file) complete with ICD files (IEC device
capability files) and substation topology which will enable easy extension of the
substation in future. The offered products shall be suitable for efficient and
reliable operation and maintenance support of the substations.
The SA system shall be state-of-the art design suitable for operation in high
voltage substation environment, follow the latest engineering practice, ensure
long term compatibility requirements and continuity of equipment supply and the
safety of the operating staff.
As shown in the SA system structure, protection is an integral part of the SA
system and protective relays shall be directly connected to the interbay bus in
order to provide unrestricted access to all data and information stored in the
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relays and for changing protection parameters from the remote control location.
Failure behaviour of the hardware and software functions shall be addressed and
related diagnostic and rectification working instructions shall be provided. The
system performance, if failure of communication to NLDC, main and redundant
computer base workstations, central functions, data model, control and protection
IED’s, station and bay level communication shall also be clearly addressed.
5.18.3.2Modes of Operation
The operator stations and specified remote users shall have following operational
modes,each password protected.
MonitoringAbility to select graphic displays and lists for viewing only. No
capability to acknowledge alarms, complete controls or select items for inclusion
in program functions.
Control Selection of graphic display and lists. Able to acknowledge station and
SA alarms, complete controls, dressing, etc. associate with normal real time of
the control of the substation.
SA Engineering Provides all the SA monitoring functions, together with online
facilities for program/database/format modifications and checking without the
possibility of executing power system controls.
System Manager Provides access to all system functions, including assignment
of passwords and system maintenance activities.
In addition a facility to provide access to the numerical Protection relays
including AVR, change/modify relay settings & AVR parameters and fault and
disturbance data shall be provided.
A series of passwords shall be personally assigned to operators in each of the
above categories.
It shall be possible for substation operators to log on either of the substation
workstation and to be allocated the appropriate mode of operation relevant to the
password. SA System Engineering work and access to the protection relays and
fault and disturbance recording information shall generally be carried out at the
Engineering workstation or remote master station.
All the workstation and the system database shall function as a system. It shall
not be necessary for example to acknowledge an alarm at more than one
workstation.
Similarly, an operator manual entry applied at a workstation shall be immediately
displayed at other workstations where this data is presented.
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5.18.3.3Project Specifications
Specific functions required and boundary conditions of the SA are detailed
elsewhere in this specification. The project specific drawings are attached:
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Overall single line diagram
General system architecture
Location of substation buildings
Control and operation principles
Protection schemes
5.18.3.4Vendor’s Experience and Local Support
Only experienced and technically capable manufacturers with minimum 10 years
experience in design and supply of control and protection systems for electricity
transmission and distribution applications will be accepted. Preferred
manufactures will be those who have experience in deliveries of the full scope of
station automation systems and services. This experience has to be substantiated
by means of reference installations being in service under similar environmental
conditions for at least 10 years. In order to assess the vendor’s experience with
similar projects, the vendor is required to submit the following with his bid:
· Technical design specifications and description of SA
· Catalogues and brochures of equipment and devices offered
· Reference list
The vendor shall assure for long-term maintenance and availability of spares.
Moreover, a guarantee shall be submitted for the availability of spares during the
lifetime of the SA equipment (not less than10 years).
5.18.3.5Quality Assurance and Inspection
Quality Assurance of design and development, production, installation and
servicing of material and workmanship shall be governed by ISO 9001.
Supporting documents to prove ISO 9001 third party approvals shall be provided
with the offer.
The SA system shall be pre-assembled and tested at the vendor’s workshop
before shipment.
5.18.4
General System Design
The system shall be so designed that personnel without any background in
microprocessor based technology can operate the system easily after they have
been provided with some basic training.
System control from the substation control room will be with the help of an
Industrial Computer (PC) operated by a mouse. The following HMI (Human
Machine Interface) functions shall be provided:
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· Acquisition and plausibility check of switchgear status
· Control of switchgear
· Remote checking of device parameters and activation of alternative parameter
sets in the connected protective relays
· Display of actual measured values (U, I, P, Q, f)
· Display of events
· Display of alarms
· Display of trends
· Sequence control functions
· Dynamic busbar coloring
· Disturbance records and fault location
· System self-supervision
· Hard copy printing
The offered SA shall support remote control and monitoring from NLDC centre
via an industrial grade gateway with redundant CPU as well as redundant DC/DC
converters. PC based gateways which contains moving parts will not be accepted.
The gateway should be designed for a life of at least 20 years. The gateway shall
provide for communication to/from remote control centers via IEC60870-5-101
protocol. Even if the Station PC is not available, it shall be possible to control the
station from NLDC centre as well as from the backup control panel in the
individual bays with all interlocks. Interlocking in case of emergency (i.e if bay
controller fails) should be waived locally by means of a switch with key lock by
the maintenance engineer for all the switchgear.
Maintenance, modification or extension of components shall not require a
shutdown of the whole station automation system. Self-monitoring of single
components, modules and communication shall be incorporated to increase the
availability of the equipment while minimizing maintenance time to repair.
As shown in the system drawing, the SA shall be structured in two levels - station
level and bay level. The data exchange between the electronic devices on both
levels shall take place via an inter-bay bus as per IEC 61850 standards. The entire
station shall be controlled and supervised from the station level PC. It shall also
be possible to control, monitor and protect each individual bay from the
respective bay level equipment for maintenance purposes or if the communication
to a particular bay should fail. Clear control priorities shall prevent initiation of
operation of a single switch at the same time from more than one of the various
control levels viz., NLDC, station level, bay level or switchgear (apparatus) level.
The priority shall always be with the lowest enabled control level.
Each bay control and protection unit shall be independent of each other and its
functioning shall not be affected by any fault occurring in any of the other bay
control and protection units of the station.
The SA shall contain the following main functional parts:
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· Human Machine Interface (HMI) with process database
· Gateway function for remote control via an industrial grade hardware
· Dial in facility / laptop workstation for protection relay parameterisation,
disturbance analysis and SA system fault analysis.
· Data exchange between the different system components via high speed bus
· Bay level devices for control, monitoring and protection
· Bay oriented local control and protection panels with mimic inserts
· Facility for emergency operation of all the switchgear, if bay controller fails.
(Key / master key system)
The main process information of the station shall be stored in distributed
databases. The system shall be based on a de-centralized concept with bay
oriented distributed intelligence for safety and availability reasons. Functions
shall be decentralized, object oriented and located as close as possible to the
process.
The substation monitoring/protection system shall supply data for maintenance,
repair and remote parameter setting of protection and control devices in the
switchyard.
In the event of a fault in the electrical network, the substation monitoring shall
provide a quick means for collecting the relevant and critical data of the fault.
The monitoring system shall be suitable for the supervision and monitoring of all
the secondary (IED) and primary devices in a substation including future
extensions.
Maintenance, modification or extension of components shall not cause a shut-off
of the whole station monitoring system. Self-monitoring of single components,
modules and communication shall be incorporated to increase the availability and
the reliability of the equipment and minimize maintenance.
It shall be possible to access all protection and control devices for reading the
terminal parameters (settings). The setting of parameters or activation of
parameter sets shall be restricted by password to the protection engineer.
One remote computer should be provided with the access to SMS with different
access levels. The required SMS software and application specific firmware (for
relay parameterisation) shall be provided with associated tools and equipment.
The required engineering tools analysing software also shall be provided/installed
both in the station PC and the remote Master Analysis station. A backup copy of
all the software shall be provided in CDs.
5.18.5
Flexibility and Scalability
The offered SA system concept shall be flexible and shall permit future
extensions to be realized easily as per IEC 61850 standards. Preference will be
given to those suppliers who are in a position to provide protection and control
devices which can be freely adapted to the application functions required.
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5.18.6System Hardware
5.18.6.1 Operator Station
The main operator station shall be based on an industrial PC hardware and highresolution full-graphics screen with manufacturers’ standard type tested software
operating under Windows environment. An black & white printer and a Hard
Copy colour printer shall be connected via LAN to the operator station.
Dual station computers shall control the SA system and drive the work stations
and other peripherals. One of the station computers shall operate the system in the
“on line” state while the other acts as a “redundant hot standby”. The standby
computer shall be continuously updated and shall immediately take over the SA
system duties without interruption or transfer mechanism should the on line
operator workstation fail. The Industrial computers shall be supplied in cubicles
of protection class IP54 or better along with the GPS clock & switches as
required.
Disturbance Records shall be analysed using the installed Disturbance Record
Analysis programs. The Disturbance Records will be collected, over the interbay
bus, from the connected IED’s by the system software. All necessary facilities
shall be provided to allow the system to perform spontaneous upload of
Disturbance data or upload them in a pre-programmed manner. The Event printer
shall print events spontaneously as they arrive in the main operator station.
Each uploaded data report file shall be reported on one line that shall contain:
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The event date and time
The name of the event object
A descriptive text
The state or value of the object
The information fields above shall be structured in columns for maximum
readability.
The hard copy printer shall permit printing of any picture (or part thereof) from
the station level PC’s using easily accessible commands from the window menus.
The main Station PC`s shall be supplied by the station DC battery and a UPS
system with a supply duration of not less than 30 minutes shall be provided to
supply the monitor and the printers.
Atleast 32 window annunciator unit shall be directly connected to the main
Station PC`s to monitor the same and also to annunciate common station
abnormal/fault conditions.
5.18.6.2Station Inter-bay Bus
The LAN connecting the industrial computer based operator workstations,
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printers shall be Ethernet 802.3 LAN, Protocol TCP/IP (10 Mbits/ sec or higher)
and the physical medium shall be thin Ethernet or fiber optic bus, provided this
LAN is kept within the confines of the control room.
The bay control and protection units shall be connected via glass fiber optic
cables to a station inter-bay bus using industrial grade Ethernet switches. The
station bus according IEC 61850-8 is today mapped to MSS / Ethernet (with
priority tagging and with 100 MS/s). The standard is not making any provision on
the Ethernet communication infrastructure. To at least ensure a certain level of
quality, performance and availability at least the following described criteria’s
have to be fulfilled concerning the Ethernet switches and topology.
Industrial grade Ethernet switches that fulfill the hardened requirements
concerning temperature, EMC and power supply (110 V DC from the station
battery) suitable to be installed in substations shall be provided, i.e. the same data
as common for numerical protection. The use of Ethernet Hubs is not permitted as
they do not provide collision free transmission. The switches shall support
priority tagging and open standards for ring management like fast spanning tree to
ensure that e.g. for later system extension utility has not to rely on one switch
supplier only. External switches shall be supplied as they have the advantage that
there is no interruption or reconfiguration of the Ethernet ring if one or several
bay devices are taken out of service. To increase reliability the Ethernet Switches
shall have redundant power supply & shall be powered from two different station
batteries.
5.18.6.3 Protection and Control IED’s and Local Back-up Control Mimic on 230 kV &
132 kV Level
The bay control IED’s, based on microprocessor technology, shall use numerical
techniques for the calculation and evaluation of externally input analogue signals.
They shall incorporate select-before-operate control principles as safety measures
for operation via the HMI. They shall perform all bay related functions, such as
protection, commands, bay interlocking, data acquisition, data storage, event and
disturbance recording and shall provide inputs for status indication and outputs
for commands. They shall be directly connected to the switchgear without any
need for separate interposing equipment or transducers.
The numerical bay control IED shall be provided with a minimum of nine (9)
configurable (current or voltage) analogue input channels and adequate number of
binary input & output channels which are galvanically isolated from the SA
system. The channels shall also be individually separated from each other. HV
switchgear and instrument transformers shall be directly connected to the bay
level IED without any interposing equipment.
The devices shall meet the requirements for withstanding electromagnetic
interference according to relevant parts of IEC 255 to conform to the high
requirements for operation on the secondary system of HV switchgear.
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The 230 kV &132 kV bay control & protection IED shall have the following
features:
- A minimum of 9 configurable analogue channels
- At least 32 binary inputs, 24 signal relays and 2 command relays
- 16 nos. LED’s on the front of the unit for indication
- Synchrocheck function
- Power function which can be configured to measure forward or reverse,
active or reactive power
- Four (4) independently settable parameter setting groups, settable/selectable
locally or remotely via the HMI programme
- 4 line Local Display Unit (LDU or front HMI) on the front of the relay which
can display both input as well as measured quantities: frequency, phase
currents, phase voltages, active power, reactive power, etc.
- High speed bus serial communication port as per IEC 61850 standards
- Sequence of Events Recorder with a buffer for 256 events and a resolution of
1 msec. The events that are to be recorded should be freely programmable.
These could be alarm/trip signals, external signals connected to optocoupler
inputs, internal signals, etc. Once events are defined, they are recorded in
chronological order as they occur.
- Disturbance Recorder function which can record 9 analogue values, 16
Binary signals and 12 analogue channels for internal measurement values. It
shall be possible for the Disturbance Recorder function to be triggered by
any internal or external binary signal or internal protective function.
- Comprehensive self-supervision
- Battery-free memory back-up of Event and Disturbance Records
- Logic functions (AND, OR, bistable flip flop, etc.)
- Delay/Integrator function
The numerical bay control IED’s shall be mounted together with all the relevant
bay protective relays in cubicles of Protection Class IP54 or better. Distributed
back-up control mimics with associated switches meters and Indicating LED’s
shall also be provided on these cubicles. These cubicles shall be installed in an
air-conditioned room in the substation.
The distributed backup mimic for Local Control shall be installed next to the bay
controller IED, which can be used in case of maintenance or emergency or if bay
control IED fails. Local bay control via the back-up control mimic on the Control
& Protection cubicles shall incorporate the same user safety measures e.g. bay
interlocking, synchrocheck, interlock override user guidance, etc. as the station
HMI. Local bay control shall be key-locked and the control either from GIS local
control panel or station HMI or from remote shall be disabled if the local/remote
selector switch on the back-up control mimic is in the ‘local’ position.
The electronic system has to be provided with functions for self-supervision and
testing. Each circuit board shall contain circuits for automatic testing of its own
function.
Faults in the bay control IED shall be indicated on a front HMI and a message
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shall be sent to the station level HMI. The time for fault tracing and replacement
of a faulty unit shall be reduced to a minimum. The supervision shall also cover
the power supply system, the internal system bus and the ability of the central
processing module to communicate with different printed circuit boards.
Failure of any single component within the equipment shall neither cause
unwanted operation nor lead to a complete system breakdown. The n-1 criteria
must be maintained in worst case scenarios also. Further, a single failure must not
have any affect on the primary system, which is monitored and controlled.
Only the backup protection can be incorporated in the bay control unit and not the
main protections. Main protection shall be provided separately.
All IED`s shall have at least 5 years of successful proven experience in HV
applications.
5.18.7 Software Structure
The software package shall be structured according to the SA architecture and
strictly divided in various levels. It shall be possible to extend the station with the
minimum possible effort. Maintenance, modification or extension of components
of any feeder may not force a shut-down of the parts of the system which are not
affected by the system adaptation.
Confirmation that the software programs will be supported for a minimum of 20
years is required to be submitted with the bid.
It shall be the responsibility of the contractor to obtain any license required for
the operation software. The contractor shall indemnify the client against all
claims of infringement of any patent, registered design, copyright, trademark or
trade name or other intellectual property right.
5.18.7.1Station Level Software
5.18.7.1.1Human Machine Interface (HMI)
The base HMI software package for the operator station shall include the main
SA functions and it shall be independent of project specific hardware version and
operating system. It shall further include tools for picture editing, engineering and
system configuration. The system shall be easy to use, to maintain, and to adapt
according to specific user requirements. The System shall contain a library with
standard functions and applications.
5.18.7.1.2Operating System
Windows Workstation operating system shall be used for the operator station as it
supports several standard system features, e.g support for several Windows office
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applications, multitasking, security levels, data exchange mechanisms (DDE,
OLE), open data base communication standards (ODBC) and a standardised,
user-friendly look & feel HMI.
5.18.7.2Bay Level Software
5.18.7.2.1System Software
The system software shall be structured in various levels. This software shall be
placed in a non-volatile memory. Its lowest level shall assure system performance
and contain basic functions, which shall not be accessible by the application and
maintenance engineer for modifications. The system shall support the generation
of typical control macros and a process database for user specific data storage.
5.18.7.2.2Application Software
In order to ensure robust quality and reliable software functions, the main part of
the application software shall consist of standard software modules built as
functional block elements. The functional blocks shall be documented and
thoroughly tested. They shall form part of a library.
The application software within the control/protective devices shall be
programmed in a functional block language.
5.18.8 System Testing
The supplier shall submit a test specification for factory acceptance test (FAT)
and commissioning tests of the station automation system for approval. For the
individual bay level IED’s, applicable Type Test certificates shall be submitted.
The manufacturing phase of the SA shall be concluded by a Factory Acceptance
Test (FAT). The purpose is to ensure that the Contractor has interpreted the
specified requirements correctly. The general philosophy shall be to deliver a
system to site only after it has been thoroughly tested and its specified
performance has been verified with site conditions simulated to the extent
possible in a test lab. If the FAT involves only a certain portion of the system for
practical reasons, it has to be assured that this test configuration contains at least
one unit of each and every type of equipment incorporated in the delivered
system. The bids should prove that they have the required testing tools to test the
IEC 61850 based SA system and such tools shall be used and shown to the
engineer at FAT.
If the complete system consists of parts from various suppliers, the FAT shall be
limited to sub-system tests. In such cases, the complete system test shall be
performed at site together with the Site Acceptance Test (SAT).
5.18.9 System functions
5.18.9.1Control Unit Functions
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5.18.9.1.1Control
The different high voltage apparatuses within the station shall either be operated
manually by the operator or automatically by programmed switching sequences.
The control function shall comprise:
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Commands from different operator places, e.g. from the associated control
centre (NLDC), station HMI, or local control panel according to the operating
principle
Select-before execute commands
Operation from only one operator place at a time.
Operation depending on conditions from other functions, such as interlocking,
synchrocheck, operator mode, or external status conditions.
The control function shall also include:
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Prevention of double operation
Command supervision
Selection of operator place
Block/deblock of operation
Block/deblock of updating of position indications
Manual setting of position indications
Overriding of the interlocking function (Second key switch)
Switchgear run time supervision
5.18.9.1.2Status Supervision
The position of each switchgear, e.g. circuit breaker, isolator, earthing switch,
etc., shall be permanently supervised. Every detected change of position shall be
immediately visible on the screen in the single-line diagram, recorded in the event
list, and a hard copy printout shall be produced. Alarms shall be initiated in cases
when spontaneous position changes have taken place.
Each position of an apparatus shall be indicated using two binary auxiliary
normally closed (NC) and normally open (NO) contacts. An alarm shall be
initiated if these position indications are inconsistent or indicate an excessive
running time of the operating mechanism to change position.
5.18.9.1.3Interlocking
The interlocking function prevents unsafe operation of apparatuses such as
isolators and earthing switches within a bay or station wide. The operation of the
switchgear shall only be possible when certain conditions are fulfilled. The
interlocking function is required to be decentralized so that it does not depend on
a central control device. Communication between the various bays for the station
interlocking shall be hard wired/take place via interbay bus.
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An override function shall be provided, which can be enabled to by-pass the
interlocking function via a key/password, in cases of maintenance or emergency
situations.
5.18.9.1.4Measurements
Analogue inputs for voltage and current measurements shall be connected directly
to the voltage transformers (VT) and the current transformers (CT) without
intermediate transducers. The correlated values of active power (W), reactive
power (VAr), frequency (Hz), and the rms values for voltage (U) and current (I)
shall be calculated.
5.18.9.1.5Event and Alarm Handling
Events and alarms shall be generated either by the switchgear, by the control
devices and by the station level unit. They shall be recorded in an event list in the
station HMI. Alarms shall be recorded in a separate alarm list and appear on the
screen. All or a freely selectable group of events and alarms shall also be printed
out on an event printer. The alarms and events shall be time tagged with a time
resolution of 1 ms. The time tagging shall be done at the lowest level where the
event occurs and the information shall be distributed with the time tagging.
5.18.9.1.6Time Synchronisation
The time within the SA shall be set via a GPS Clock Receiver connected directly
to the Bay Level LAN. The time shall then be distributed to the control/protective
devices via the high speed optic fiber bus. An accuracy of ±1 ms within the
station is required.
5.18.9.1.7Synchronism and Energising Check
The synchronism and energizing check functions shall be distributed to the
control and/or protective devices and shall have the following features:
· Adjustable voltage, phase angle, and frequency difference.
· Energising for dead line - live bus, or live line - dead bus.
· Settings for manual close command shall be adaptable to the specific
switchgear.
5.18.9.1.8Voltage Selection
The voltages, which are relevant for the synchrocheck functions, depend on the
station topology i.e. on the positions of the circuit breakers and/or the isolators.
The correct voltage for synchronising and energising is derived from the auxiliary
switches of the circuit breakers, isolator, and earthing switch and shall be selected
automatically by the control and protection IED.
5.18.9.2HMI Functions
5.18.9.2.1General
The operator station HMI shall provide basic functions for supervision and
control of the substation. The operator shall give commands to the switchgear via
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the station monitor with the help of mouse clicks on soft-keys.
The HMI shall provide the operator with access to alarms and events displayed on
the screen. Besides these lists on the screen, there shall be a print out of hard
copies of alarms or events in an event log. The Alarm List shall indicate
persisting and fleeting alarms separately.
An acoustic alarm shall indicate abnormalities and all unacknowledged alarms
shall be accessible from any screen selected by the operator.
Following standard pictures shall be available from the HMI:
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Single line diagram showing the switching status and measured values
Control dialogues
Measurement dialogues
Blocking dialogues
Alarm list, station / bay oriented
Event list, station / bay oriented
System status
Checking of parameter setting
5.18.9.2.2HMI Design Principles
Consistent design principles shall be provided with the HMI concerning labels,
colours, dialogues and fonts. Non-valid selections shall be dimmed out.
Object status shall be indicated using different status colours for:
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Selected object under command
Selected on the screen
Not updated, obsolete value, not in use or not sampled
Alarm or faulty state
Warning or blocked
Update blocked or manually updated
Control blocked
Normal state
Busbar colouring to show live & dead bus.
5.18.9.2.3Process Status Displays and Command Procedures
The process status of the substation in terms of actual values of currents, voltages,
frequency, active and reactive powers as well as the positions of circuit breakers,
isolators and transformer tap changers are displayed in the station single line
diagram.
In order to ensure a high degree of security against unwanted operation, a special
"select – before - execute" command procedure shall be provided. After the
"selection" of a switch, the operator shall be able to recognize the selected device
on the screen and all other switchgear shall be blocked. After the “execution” of
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the command, the operated switch symbol shall blink until the switch has reached
its final new position.
The system shall permit the operator to execute a command only if the selected
object is not blocked and if no interlocking condition is going to be violated The
interlocking conditions shall be checked by the interlocking scheme which is
implemented on bay level.
After command execution, the operator shall receive a confirmation that the new
switching position is reached or an indication that the switching procedure was
unsuccessful with the indication of the reason for non-functioning.
5.18.9.2.4System Supervision Display
The SA system shall feature comprehensive self-supervision such that faults are
immediately indicated to the operator before they possibly develop into serious
situations. Such faults are recorded as faulty status in a system supervision
display. This display shall cover the status of the entire substation including all
switchgear, IED’s, communication links, and printers at the station level, etc.
5.18.9.2.5Reports
The SA shall generate reports that provide time related information on measured
values and calculated values. The data displayed shall comprise:
Trend reports:
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Day (mean, peak)
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Month (mean, peak)
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Semi-annual (mean, peak)
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Year (mean, peak)
Historical reports:
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Week
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Month
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Year
It shall be possible to select displayed values from the database on-line in the
process display. Scrolling between e.g. days shall be possible. Unsure values shall
be indicated. It shall be possible to select the time period for which the specific
data are kept in the memory.
This report shall be printed automatically at pre-selected times. It shall also be
possible to print this report on request.
5.18.9.2.5Trend Display (Historical Data)
A trend is a time-related follow-up of process data. The analogue channels of all
the connected bay level devices on the 230 kV &132 kV level shall be illustrated
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as trends. The trends shall be displayed in graphical form as columns or curve
diagrams with 10 trends per screen as maximum.
It shall be possible to change the type of value logging (direct, mean, sum, or
difference) on-line in the window. It shall also be possible to change the update
intervals on-line in the picture as well as the selection of threshold values for
alarming purposes.
5.18.9.2.5Event List
The event list shall contain events, which are important for the control and
monitoring of the substation. The time has to be displayed for each event.
The operator shall be able to call up the chronological event list on the monitor at
any time for the whole substation or sections of it.
A printout of each display shall be possible on the hard copy printer.
The events shall be registered in a chronological event list in which the type of
event and its time of occurrence are specified. It shall be possible to store all
events in the computer. The information shall be obtainable also from printed
event log.
The chronological event list shall contain:
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Position changes of circuit breakers, isolators and earthing devices.
Indication of protective relay operations
Fault signals from the switchgear
Violation of upper and lower limits of analogue measured value.
Loss of communication
Filters for selection of a certain type or group of events shall be available. The
filters shall be designed to enable viewing of events grouped per:
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Date and time
Bay
Device
Function
Alarm class
5.18.9.2.5Alarm List
Faults and errors occurring in the substation shall be listed in an alarm list and
shall be immediately transmitted to the control centre. The alarm list shall
substitute a conventional alarm tableau, and shall constitute an evaluation of all
station alarms. It shall contain unacknowledged alarms and persisting faults. Date
and time of occurrence shall be indicated.
The alarm list consists of a summary display of the present alarm situation. Each
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alarm shall be reported on one line that contains:
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The alarm date and time
The name of the alarming object
A descriptive text
The acknowledgement state
The operator shall be able to acknowledge alarms, which shall be either audible
or only displayed on the monitor. Acknowledged alarms shall be marked at the
list.
Faults that appear and disappear without being acknowledged shall be specially
presented in a separate list for fleeting alarms. For example due to bad contacts or
intermittent operation.
Filters for selection of a certain type or group of alarms shall be available as for
events.
5.18.9.2.5Object Picture
When selecting an object such as a circuit breaker or isolator in the single line
diagram, first the associated bay picture shall be presented. In the selected object
picture, all attributes such as
· type of blocking,
· authority
· local / remote control
· NLDC/SA control
· errors,
· etc.,
shall be displayed.
5.18.9.2.6Control Dialogues
The operator shall give commands to the system by means of soft keys located on
the single line diagram. It shall also be possible to use the keyboard for soft key
activation. Data entry is performed with the keyboard.
5.18.9.2.7User Authority Levels
It shall be possible to restrict the activation of the process pictures of each object
(bays, apparatus, etc.) to a certain user authorization group. Each user shall then
be given access rights to each group of objects, e.g.:
·
·
·
·
Display only
Normal operation (e.g. open/close apparatus)
Restricted operation (e.g. by-passed interlock)
System administrator
For maintenance and engineering purposes of the station HMI, the following
SEC 05: Protection, Control SAS
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authorization levels shall be available:
· No engineering allowed
· Engineering/configuration allowed
· Entire system management allowed
The access rights shall be defined by passwords assigned during the log-in
procedure. Only the system administrator shall be able to add/remove users and
change access rights.
5.18.9.3
System Performance
The refresh/update times on the operator station PC under normal and calm
conditions in the substation shall be according to the levels specified below:
Function
Typical
values
Exchange of display (first reaction)
<1s
Presentation of a binary change in the process display
< 0.5 s
Presentation of an analogue change in the process display < 1 s
From order to process output
< 0.5 s
From order to update of display
< 1.5 s
5.18.9.4
System Reliability
The SA system shall be designed to satisfy very high demands for reliability and
availability concerning:
·
·
·
·
·
·
·
·
·
·
·
·
·
·
·
·
·
Solid mechanical and electrical design
Security against electrical interference (EMI)
High quality components and boards
Modular, well-tested hardware
Thoroughly developed and tested modular software
Easy-to-understand programming language for application programming
Detailed graphical documentation, according to IEC 1131-3, of the application
software
Built-in supervision and diagnostic functions
After sales service
Security
Experience of security requirements
Process know-how
Select before execute at operation
Process status representation as double indications
Distributed solution
Independent units connected to the local area network
Back-up functions
SEC 05: Protection, Control SAS
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· Panel design appropriate to the harsh electrical environment and ambient
conditions
· Panel grounding to provide immunity against transient ground potential rise
5.18.9.5
Configuration Tools
The configuration of the station HMI shall be made using the operator station
working in Windows NT environment. The various functions shall be customised
by easy to use interactive configuration tools. Configuration shall include the
visual presentation of the object, adaptations needed in process database and
adaptations of the communication configuration data.
A portable Personal Computer (PC) as a service unit shall be foreseen for on-site
modifications of the control and protection devices. The service unit shall be used
for documentation, test and commissioning.
The PC based service & support system shall be used for the following purposes:
·
·
·
·
·
·
·
·
System configuration
System testing
Help functions
Program documentation
Down- and up-loading of programs
System commissioning
Data base management
Changing peripheral parameters
The service & support system shall be able to monitor data in the running
substation control system and to present changing variables on the display screen
in graphic representation.
5.18.9.6
Documentation
The following documentation shall be provided for the system during the course
of the project and they shall be consistent, CAD supported, and of similar
look/feel:
·
·
·
·
·
·
·
·
·
·
·
List of Drawings
Control Room Lay-out
Assembly Drawing
Single Line Diagram
Block Diagram
Circuit Diagram
List of Apparatus
List of Labels
Functional Design Specification (FDS)
Test Specification for Factory Acceptance Test (FAT)
Logic Diagram
SEC 05: Protection, Control SAS
5/42
·
·
·
·
·
5.18.9.7
List of Signals
Operator’s Manual
Product Manuals
Calculation for uninterrupted power supply (UPS) dimensioning
High quality SCD file
Indicating Meters in Local Back-up Control Panels
Each circuit shall be equipped with Indicating meter for measurement of three
phase currents, voltages, frequency, power factor, active and reactive power.
Repeat pulse outputs are to be provided from all energy meters, where specified.
5.18.9.8
Trip Circuit and Power Supply Supervision
Trip circuit supervision relays shall be provided to monitor each of the trip
circuits of circuit-breakers in the relay panel and each relay shall have sufficient
contacts for visual/audible alarm and indication purposes.
The trip circuit supervision scheme shall provide continuous supervision of the
trip circuits of the circuit-breaker in either the open or closed position and
independent of Local or Remote selection at the local operating position. It shall
be suitable for use in single and three pole tripping schemes as appropriate.
Relay elements shall be delayed on drop-off to prevent false alarms during faults
on d.c. wiring on adjacent circuits, or due to operation of a trip relay contact.
Series resistances shall be provided in trip circuit supervision circuits to prevent
male tripping of a circuit-breaker if a relay element is short circuited.
Relay alarm elements should be equipped with self resetting flag indicators.
Where specified, time delayed power supply supervision relays shall be provided
to monitor the duplicated d.c. power supplies for tripping, closing, CB fail, busbar
protection etc. within a relay panel. An alarm shall be given if either supply
voltage falls below 70% of nominal voltage for a period in excess of 3 secs. The
relay shall be equipped with a self resetting flag indicator, and shall be suitable
for continuous operation at 125% of nominal d.c. voltage.
5.18.9.9
BUSBAR VOLTAGE SELECTION
Where required, selected voltage references, one for each busbar, shall be
employed for all indications, metering, protection and synchronizing where
appropriate. The correct voltage selection for the requirements of each circuit
according to the busbar to which it is connected shall be obtained by direct use of
auxiliary contacts on busbar selector switches.
5.18.9.10 Availability Calculations
The contractor shall submit availability calculations for the offered substation
SEC 05: Protection, Control SAS
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automation system.
5.19
DIAGRAMS
The Contractor shall submit schematic diagrams for consideration of the Engineer
within six months of the Contract commencement date. Prior to preparation of
schematic diagrams, the Contractor shall provide single line, block and logic
diagrams in order to agree the circuit schemes and operating modes.
The Contractor will be provided with a set of drawings for each Substation as
soon as possible after award of Contract. As part of the Contract documentation,
the Contractor shall provide integrated sets of complete drawings (schematic and
wiring diagrams, cable schedules, etc).
5.20
CURRENT TRANSFORMER CALCULATIONS
The Contractor shall submit to the Employer detailed calculations substantiating
the parameters of the current transformers he proposes to provide. They shall be
presented within six weeks of the Contract commencement date.
5.21
DIGITAL FAULT AND DISTURBANCE RECORDER [DFDR]
Not Applicable.
5.22
Energy Meter (Tariff Metering) :
Meter requirement:
1. Programmable meter
2. Adjustable different tariff
3. 110-400V flexible input voltage setting
4. 1(10) A current rating
5. Accuracy class to be ±0.2for kwh and ±0.5 for kvarh
6. RS232/485 Port for Medem interface
7. Standard metering protocol for remote interface
8. Data storage of 16 [email protected] interval and of 90days
9. Optical head and software to upload and download of meter data
10. Passward protection for programming and for configuaration
11. Configurable display, including meter ID, Power quadrant display etc .
12. Provision for quick reading scroll, reset etc(Programmable)
Additional requirement:
SEC 05: Protection, Control SAS
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1. Online test facility of meter(with TTB) and with Security Sealing Provision.
2. TTB’s should be at the suitable accessible panel front location with meter
3. Meter cabinet should be exclusive for tariff metering only and have sufficient
Security Sealing provision, provided with 220V, 5A two pin socket outlet for
modem power, Auxilliary bias power, Testing Equipment power etc.
4. All main metering CT, VT should be terminated to metering panel directly
including star point(4 wire).
5. Backup metering circuit may be shared for other purpose.
6. VT MCB(both main and backup) should be located in the metering panel. Down
stream VT MCB rating should be less than that of up stream.
7. All CT & VT terminals shoud have Security Sealing provision.
Normal display list:
Scroll order
Display Item Name
1
Complete LCD Test
2
Present date
3
Present time
4
Current billing total kWh-Del
5
Current billing total kWh-Rec
6
Current billing total kVARh-(Q1+Q4)
7
Current billing total kVARh-(Q2+Q3)
8
Current billing maximum kW-Del
9
Current billing maximum kW-Del Date
10
Current billing maximum kW-Del Time
11
Current billing cumulative kW-Del
12
Current billing maximum-Rec
13
Current billing maximum kW-Rec Date
14
Current billing maximum kW-Rec Time
15
Current billing cumulative kW-Rec
16
Phase A Voltage
17
Phase B Voltage
18
Phase C Voltage
19
Phase A Current
20
Phase B Current
21
Phase C Current
22
Phase A Voltage angle
SEC 05: Protection, Control SAS
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23
Phase B Voltage angle
24
Phase C Voltage angle
25
Phase A Current angle
26
Phase B Current angle
27
Phase C Current angle
28
System PF-arithmatic
29
Line frequency
Alternate Mode Display list:
Scroll order
Display Item Name
1
Complete LCD Test
2
Present date
3
Present time
4
Current billing total kWh-Del
5
Current billing total kWh-Rec
6
Current billing total kVARh-(Q1+Q4)
7
Current billing total kVARh-(Q2+Q3)
8
System PF-arithmatic
9
Line frequency
Load profile(Cumulative meter reading) and Instrumentation profile Data in the following
format should be stored in each 30 min interval for at least 100 days.
Interval Data(Load profile):
Interval Data Mode: Cumulative Engineering Units
Time
kWh-Del
Date: 1/31/2015
00:00
00:30
01:00
01:30
0
0
0
0
kWh-Rec
kVARh-(Q1+Q4)
0
0
0
0
kVARh-(Q2+Q3)
0
0
0
0
0
0
0
0
Interval Data(Instrumentation):
Set-1
Time
End Phase A Voltage
End Phase A Voltage
End Phase A Voltage
Average System kW
Date:1/31/2015
SEC 05: Protection, Control SAS
5/46
13:45
61.0544
61.1424
61.072
0
Set-2
Time
End Phase A Current
End Phase A Current End Phase A Current Average System PF-arithmatic
Date:1/31/2015
13:45
0.0008
0.0004
0.0004
-0.7002
Self Read Feature for at least 12 month’s billing history.
SEC 05: Protection, Control SAS
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POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 6
AUXILIARY POWER AND CONTROL CABLES
SECTION6
AUXILIARY POWER AND CONTROL CABLES
TABLE OF CLAUSES
6.1 SCOPE ...................................................................................................... 6/3
6.2 GENERAL DESCRIPTION OF INSTALLATION .................................... 6/3
6.3 STANDARDS ............................................................................................ 6/3
6.4 CABLE INSTALLATION ......................................................................... 6/4
6.4.1 GENERAL6/4
6.4.2 INSTALLATION CRITERIA ....................................................................................................... 6/4
6.4.3 REDUCED FIRE PROPAGATION .............................................................................................. 6/5
6.4.4 TYPE APPROVAL .................................................................................................................... 6/5
6.4.5 CABLE SIZING AND ROUTING ................................................................................................ 6/5
6.5 CABLE CONSTRUCTION ....................................................................... 6/7
6.5.1 OVERSHEATHS ....................................................................................................................... 6/7
6.5.2 ARMOURING .......................................................................................................................... 6/7
6.5.3 LAYING UP ............................................................................................................................. 6/7
6.5.4CABLE DRUMS ........................................................................................................................ 6/8
6.5.5SEALING AND DRUMMING ...................................................................................................... 6/8
6.5.6 SPARE CABLE ........................................................................................................................ 6/8
6.5.7 JOINTING ACCESSORIES ........................................................................................................ 6/8
6.6 TYPES OF CABLE ................................................................................... 6/9
6.6.1 LOW VOLTAGE CABLES ......................................................................................................... 6/9
6.6.2 CONTROL CABLES AND INSTRUMENTATION CABLES ............................................................. 6/9
6.7 STRAIGHT THROUGH JOINTS............................................................ 6/11
6.8 GENERAL METHODS OF CABLE INSTALLATION ........................... 6/11
6.9 CABLES DRAWN INTO DUCTS ........................................................... 6/12
6.10 CABLES INSTALLED IN CONCRETE TRENCHES .......................... 6/12
6.11 CABLES SUPPORTED ON RACKS, TRAYS AND LADDERS. ........... 6/13
6.12 TERMINATIONS .................................................................................. 6/15
6.12.1GENERAL ............................................................................................................................ 6/15
6.12.2POWER CABLES .................................................................................................................. 6/15
6.12.3MINERAL INSULATED CABLES ........................................................................................... 6/16
6.13 TERMINATING AND JOINTING CONDUCTORS ............................ 6/16
SEC 06: Auxiliary Power & Control Cables
6/1
6.14 CORE IDENTIFICATION ................................................................... 6/16
6.15 CABLE IDENTIFICATION AND SCHEDULES ................................. 6/17
6.16 INSPECTION AND TESTING ............................................................ 6/18
SEC 06: Auxiliary Power & Control Cables
6/2
SECTION 6
AUXILIARY POWER AND CONTROL CABLES
6.1
SCOPE
A complete cabling system for the substation 415/230V auxiliary power
requirements and the control and protection multicore cabling shall be designed,
provided, installed and commissioned by the Contractor as specified in the
Project Requirements and schedules. All ducts, cable racking and supports are to
be supplied under the Contract. The Contractor shall, furnish satisfactory
evidence as to the competence of the electricians and jointers he proposes to
employ on the cable installation and jointing works.
6.2
GENERAL DESCRIPTION OF INSTALLATION
The complete cabling installation, including that associated with control and
instrumentation, shall be managed by the Contractor, who shall be responsible for
design, procurement, installation and works/site testing of the whole installation.
The Contractor shall employ a cabling computer program to facilitate the above
and the Bidder shall describe in his Bid the cabling management procedures he
will adopt. A cable scheduling system will be imposed by the Employer.
The Contractor shall provide an installation in accordance with the best modern
practice and complete in every detail for continuous operation.
Cabling areas will include those which have natural ventilation. Cabling shall
therefore be designed for the maximum ambient temperatures expected.
To cater for future requirements, adequate provision shall be made for the
associated cables in respect of trench sizes, space for future racks or trays and
numbers of cables permitted in areas or spaces required for future equipment.
The Contractor shall submit to the Employer drawings for approval showing the
proposed cable routes, cross-sections of the trenches and arrangements of the
cable racks and trays.
The Contractor shall prepare and provide all necessary cable schedules. The cable
numbering system to be used shall be advised to the Contractor and this system
shall be followed.
The Contractor shall provide all necessary power, multicore and communications
cables required as required and specified in the Project Requirements.
6.3
STANDARDS
The cables shall comply with British Standards or International Electrotechnical
Commission (IEC) Standards and Recommendations, or any other internationally
SEC 06: Auxiliary Power & Control Cables
6/3
recognized standards, subject to the approval and acceptance of the Employer.
Any international standards referenced in the specifications and our outdated shall
be replaced with the corresponding replacement.
6.4
CABLE INSTALLATION
6.4.1
General
The cabling system shall be designed to incorporate maximum practical security,
to ensure that an incident such as fire causing loss of cable circuits in any one
route would at worst result in the interruption in operation of one unit only.
Cables with reduced fire propagation characteristics shall be provided.
Cables shall be satisfactory for operation under the atmospheric and climatic
conditions prevailing at the site and under such variations of current, voltage and
frequency as may be met under fault and surge conditions on the system.
Cables shall be derated to allow for the likely number of cables following a given
route.
The methods of installation shall be as follows:
(a)
In concrete trenches
(c)
In ducts
(d) On cable racks, trays or ladders
Control and instrumentation cables shall be screened/shielded to minimise
interference, where necessary.
6.4.2
Installation Criteria
Specific requirements shall be as detailed in the Project Requirements.
System security shall be achieved by ensuring that cables are segregated or
separated from each other as appropriate. Segregation shall be achieved by laying
cables associated with any one high voltage circuit of a pair on separate trays or
racks at least 600mm apart from the cables of the other of the pair with an
airspace, but not necessarily a physical barrier, between them.
In general, to minimize interference, control cables and instrumentation cables
shall be separated from power cables.
The following group classifications will be allocated for each cable:
i) Group A: Single core power cables,
ii) Group B: Multicore power cables,
iii) Group C: Multicore control cables and protection cables,
iv) Group D: multipair control and instrumentation or indication cables.
SEC 06: Auxiliary Power & Control Cables
6/4
In general, single core (Group A) and multicore (Group B) power cables shall be
allocated to separate racks. In a similar manner, multicore control (Group C) and
multipair (Group D) instrumentation cables shall generally be allocated to
separate trays.
There shall generally be a minimum separation of 600 mm between
instrumentation cables (Group D) and power cables (Groups A and B), and a
minimum separation of 300 mm between control cables (Group C) and power
cables (Groups A and B). However, both these separation distances may be
reduced where the two types of cable only run in parallel for a limited distance,
provided the Contractor demonstrates that the level of interference resulting will
not be detrimental to the operation of the equipment concerned.
6.4.3
Reduced Fire Propagation
A cable installation with reduced fire propagation characteristics shall be
provided, utilising cables with organic compounds which are capable of
extinguishing or considerably reducing the spread of flame along the cable.
Consideration shall also be given to ensuring that the minimum toxic or corrosive
products are given off on combustion of any organic component used in cable
construction.
6.4.4
Type Approval
Cables and accessories for use at all voltages shall have satisfactorily passed type
approval tests equal to those required by the International Electrotechnical
Commission or equivalent, and details for the cable designs offered shall be given
in Schedule E of Particulars and Guarantees.
The Contractor is to certify that the cables and/or accessories offered will be
identical in all essential particulars in respect of design, materials and
workmanship with the cables and/or accessories for which type approval
certificates are offered in support of his bid. The Contractor shall also ensure that
all materials used will be subjected to and shall have satisfactorily withstood such
tests as are customary in the manufacture of the types of cables specified.
Records of such tests shall be available for inspection, if required by the
Employer.
6.4.5
Cable Sizing and Routing
The Contractor shall be responsible for all cable sizing and routing design,
procurement, installation and testing.
Proposals for the following aspects of cable design shall be submitted for
approval:-
Routing cables along the shortest route compatible withsegregation/separation
and capacity limitations
SEC 06: Auxiliary Power & Control Cables
6/5
-
Sizing cables in accordance with length grouping, ambient temperature and
current rating
- Recording estimated lengths and later measured lengths for each cable
- Progressing the cable installation
- Producing and progressing cable schedules, cable termination schedules, and
support steelwork schedules and drawings
All necessary de-rating factors shall be applied when sizing cables, to allow for
maximum ambient temperatures, soil temperatures, values of thermal resistivity
of soil, and grouping as necessary.
Due allowance shall be made for the method of installation, depth of laying,
spacing and grouping factors.
All power cables shall be adequately rated to withstand the thermal and magnetic
effects of short-circuit fault currents equivalent to the short circuit fault rating of
the associated switchgear, except when advantage can be taken of the peak
current limiting effects of MCCB's and fuses. Screens and/or outer sheaths shall
be designed to carry the full ground fault current.
The short-time rating of all transformer and interconnector feeders shall
correspond to the maximum short-circuit conditions and be based on the previous
maximum continuous rating operating temperature, followed by the initial
asymmetric peak current, followed by the thermal steady state r.m.s. fault current
for the total duration required for the associated main and back-up protection to
operate and isolate the circuit. When protected by a circuit breaker which is not of
the current limiting type, the cable shall withstand the maximum fault current,
including asymmetric peak, for at least 3 seconds without damage.
For 415V motor supply cables the rating shall be based upon the duration of the
let-through current of the associated main circuit breaker or fuse protection. The
fault currents considered shall not include for the reduction due to the impedance
of the cables concerned.
Maximum conductor temperatures permissible during the passage of short-circuit
current shall be in accordance with cable manufacturer's recommendations and
joints and terminations shall be designed to match the cable characteristics.
For all alarm, control, indication, instrumentation, metering and protection cables,
the Contractor shall determine the impedances, load burdens and other
requirements of the cabling and associated equipment and shall provide cabling
for satisfactory operation. Particular attention shall be given to protection circuits
and the Contractor shall ensure that satisfactory operation will be achieved under
overload or short circuit conditions on the system.
The Contractor shall furnish copies of calculations and other details to show how
the ratings and cross-section areas of all cables have been obtained and the
de-rating factors for which allowance has been made. Where a cable is routed
through differing types of installation conditions, the condition giving the lowest
SEC 06: Auxiliary Power & Control Cables
6/6
cable rating shall determine the cable size.
The sizes of all cables shall be submitted to the Employer for approval and the
Employer may require the Contractor to increase the cross-sectional area of the
conductor to ensure that the required current carrying capacity and performance is
obtained. All such changes shall be made by the Contractor without extra cost.
6.5
CABLE CONSTRUCTION
6.5.1
Oversheaths
All cables shall have a black flame retardant low smoke PVC oversheath
material, to meet the fire retardant characteristics of BS 4066 and IEC 60332.
PVC sheathing shall have flame retardant properties such that the Oxygen Index
is not less than 30 when tested in accordance with A.S.T.M. D2863-77. Test
certificates stating measurement values for sample drum lengths of cable shall be
provided.
The external surface of the oversheath shall be embossed along two or more lines
approximately equally spaced around the circumference with the words
'ELECTRIC CABLE' in English. Figures for the relevant voltage grade, together
with manufacturer's name, shall be embossed on the oversheath.
The letters and figures shall be raised and shall consist of upright block
characters. The maximum size of the character shall be 13 mm and the minimum
size 15% of the approximate overall diameter of the cable. The gap between the
end of one set of embossed characters and the beginning of the next shall not be
greater than 150mm.
The minimum thickness of oversheath shall not fall below the manufacturer’s
stated value by more than 0.2mm plus 20 percent.
A means of identifying the manufacturer shall be provided throughout the length
of the cable.
6.5.2
Armouring
All multicore cables shall be provided with galvanised steel wire armour.
Single-core cables shall have copper or aluminium wire or tape armouring.
The armour shall be protected by an overall PVC or plastic sheath.
6.5.3
Laying up
The cores of multicore cables shall be laid up with a right hand direction of lay.
Where necessary, non-hygroscopic fillers, which may be applied integrally with
the bedding, shall be used to form a compact and circular cable.
SEC 06: Auxiliary Power & Control Cables
6/7
6.5.4Cable Drums
Cable drums shall be non-returnable and shall be made of timber, pressure
impregnated against fungal and insect attack, or made of steel suitably protected
against corrosion. They shall be lagged with closely fitting battens.
Each cable drum shall bear a distinguishing number on the outside of one flange.
Particulars of the cable, i.e. voltage, conductor size and material, number of cores,
type, length, gross and net weights shall also be clearly shown on one flange. The
direction of rolling shall be indicated by an arrow on both flanges. The method of
drum marking shall be to the Employer's approval.
Cable spare lengths shall be wound on to steel drums before they are handed over
to the Employer's stores.
6.5.5Sealing and Drumming
Immediately after the Works tests, both ends of each cable length shall be sealed
by means of a shrinkable cap and the end projecting from the drum shall be
adequately protected against mechanical damage during handling. The ends of
each drum length of multicore cables shall be masked red and green in
accordance with BS 6346:1989 or BS 5467.
6.5.6
Spare Cable
Spare cable and accessories, as detailed in the schedules, are required to be
included in the Contract.
6.5.7
Jointing Accessories
Cables shall be installed in continuous lengths and straight through jointing
between shorter lengths will not be permitted.
Jointing accessories shall include all necessary internal and external fittings,
insulating materials, soldering metal, glands, filling and drain plugs, armour
clamps, earth bonding terminals and filling compounds as appropriate.
Mechanical glands for the termination of elastomeric or thermoplastic insulated
cables into straight-through joints and termination accessories shall meet the
requirements of BS 6121 and shall be correctly designed for the termination of
the armouring. The gland shall not only adequately secure the armour to provide
efficient electrical continuity but shall also provide a watertight seal between the
oversheath and the inner extruded or taped bedding to prevent the ingress of
moisture. All glands shall be fitted with a substantial earth bond terminal.
The armour clamping device shall be capable of clamping the cable armour so
that the clamp withstands any short circuit current from the armour wires, through
SEC 06: Auxiliary Power & Control Cables
6/8
the gland body to the integral bonding connector.
Sealing end porcelains shall be free from defects and thoroughly vitrified so that
the glaze is not depended upon for insulation. The glaze shall be smooth and hard,
completely cover all exposed parts of the porcelain and for outdoor types shall be
a uniform shade of brown.
Porcelains must not engage directly with hard metals and, where necessary,
gaskets shall be interposed between the porcelain and the fittings. All porcelain
clamping surfaces in contact with gaskets shall be accurately ground and free
from glaze.
Sealing ends and fittings shall be unaffected by atmospheric conditions,
proximity to the coast, fumes, ozone, acids, alkalis, dust or rapid changes of air
temperature between 15°C and 65°C under working conditions.
6.6
TYPES OF CABLE
6.6.1
Low Voltage Cables
These cables shall be in accordance with IEC 60502 with a voltage rating of
0.6/1kV.
These cables shall have stranded copper conductors.
Insulation shall be XLPE with an operating temperature of 90°C.
6.6.2
Control Cables and Instrumentation Cables
6.6.2.1
General
Two types of cable shall be provided for the control and instrumentation cabling.
The first is multicore cable with stranded flexible copper conductors shall not be
less than 1.5mm2 ; which is suitable for voltages up to 300V to ground a.c. or d.c.
and currents up to 5A. These cables shall be used where a low impedance is
essential i.e. the secondary wiring of current or voltage transformers and for
circuit breaker or contactor controls. The conductor size shall be not less than 4.0
mm2 copper for CT connections.
The second type designated "signal cable" is defined as those cables carrying
milliamp, analogue or digital signals at low voltage levels (50V d.c. maximum)
used on instrument and Logic Transmission Systems. These cables shall be
multiple twisted pairs, screened and PVC covered with conductors sized 0.5mm2
minimum (1/0.8mm or 1/0.9mm diameter). The use of cable cores shall be such
that each plant analogue signal is transmitted in a twisted pair. Under no
circumstances shall the signal positive be in a different twisted pair to the
negative. 20% spare capacity shall be included in all multiple twisted pair cables.
The combinations of multiple twisted pair cables used throughout the Plant shall
be restricted to 2, 5, 10, 20, 30, 50 and 100 pairs.
SEC 06: Auxiliary Power & Control Cables
6/9
Inductive interference between primary and secondary cables due to load,
switching or unbalanced fault conditions associated with the primary circuit shall
be avoided. The more sensitive telephone, communication, analogue and digital
circuit cables shall be spaced at least 600mm from power cables.
6.6.2.2Multicore Control Cables
Cables shall comply with the construction hereabove and shall have cross-linked
polyethylene (XLPE) insulation.
All cables shall be provided with a low smoke PVC oversheath.
Multicore control cables shall be generally in accordance with IEC 60502 with
voltage rating 0.6/1 kV. Standard designs shall be for cables with 2, 3, 4, 7, 12,
19, 27 and 37 cores, and single strand conductors will be accepted up to 1.5 mm2 .
All these cables shall have galvanised steel wire armouring.
These cables shall be used where a low impedance is essential, e.g. for the
secondary wiring of current and voltage transformers and for circuit breaker and
contactor control circuits.
6.6.2.3
Multipair Instrumentation Cables
Multipair instrumentation cables shall be provided in accordance with industry
standards.
These cables shall have solid copper conductors, typically of 0.9 mm diameter
laid in twisted pairs, triplets or quads. The cables shall be polyethylene or XLPE
insulated. They shall have galvanised steel wire armouring.
Cables shall be provided with either an overall metallic tape screen or individual
tape screens round each conductor bundle to reduce interference from adjacent
circuits.
These cables shall be used for circuits with a voltage rating not exceeding 125 V
to earth and a current rating not exceeding 20 mA, where considerations of
interference and cross-talk are of great importance. Typical applications include
communications, computer signals, transducer circuits and alarms.
6.6.2.4
Oversheaths
All the cable types above shall have a black flame-retardant low smoke PVC
oversheath. In normally manned locations, especially the control building, cables
shall have a low smoke, zero halogen oversheath, so as to minimize the
generation of smoke and corrosive acid gases in the event of a fire.
6.6.2.5
Telephone Type Cables (TWPVC)
SEC 06: Auxiliary Power & Control Cables
6/10
i)
Construction
Multipair cables with l/0.9mm tinned copper conductors complying with IEC
60228, PVC insulation, individual twisted pairs, PVC bedding, single wire
armoured and low smoke PVC sheathed overall.
ii)
Insulation
PVC insulation shall be "Hard Grade" to BS 6746 with a radial thickness of
0.7mm nominal 0.57mm minimum. Minimum insulation resistance per 1000
metres of conductor at 20°C shall be 10,000 Megohms.
iii)
Laying Up
The insulated conductors shall be uniformly twisted together with a right hand lay
to form a pair. The length of lay is not to exceed 150mm and the lays for each
adjacent pair are to differ from one another in length. In any case, the length of
lay of the pairs shall be such that any cross-talk from pair to pair is the least
possible.
iv)
Core Identification
The insulation of the cores shall be colour coded in accordance with IEC 60189-2
for 20 unique cabling elements (pairs) as described in Appendix A of IEC
60189-2.
6.6.2.6
Pilot Cable
Telephone type cable laid in the ground alongside HV power cables shall take
into account the effects of induced voltages.
6.7
STRAIGHT THROUGH JOINTS
Each cable shall be run in one continuous length. Straight-through joints will not
be permitted.
6.8
GENERAL METHODS OF CABLE INSTALLATION
The arrangement of cables and the methods of laying shall be approved by the
Employer. Cables shall be installed by the following methods only: ·
·
·
In concrete trenches
In ducts
On cable racks, trays or ladders
Concrete trenches shall be provided in switchrooms. Cables shall be installed in a
manner which permits the required ratings and with due regard to the number of
cables following a given route, including future plant extensions.
SEC 06: Auxiliary Power & Control Cables
6/11
All cables routed under roads and access ways usable by vehicular traffic shall be
installed in ducts.
At all such crossings spare ducts shall be installed; the number of spare ducts
shall be two, or 20% of the total number of ducts installed at each crossing,
whichever is greater.
Mechanical protection to the Employer's approval shall be installed at all points
where the cable is vulnerable to mechanical damage. Locations where this
protection shall be installed shall include all points where cables pass through a
wall, floor, side or top of a cable trench.
Cables shall be installed in such a manner as to avoid undue risk of damage
during installation. The Contractor shall provide all necessary rollers and
supports, and bending radii shall comply with the recommendations of cable
specifications and be to the approval of the Employer.
Sunshields shall be provided in all locations where the cable would otherwise be
subjected to direct sunlight.
6.9
CABLES DRAWN INTO DUCTS
Ducts and pipes 35mm minimum in excess of cable diameter, shall be supplied
and installed by the Contractor in accordance with the building and civil works
section.
Ducts shall be of rigid PVC and shall be surrounded by l50mm minimum
thickness of concrete.
Before pulling cables through ducts, the Contractor shall remove any loose
material from the ducts, and prove them by drawing through a mandrel of slightly
less diameter than the duct. Any lubricant used shall have no deleterious effect on
the cables.
Any ducts or pipes not used shall be sealed by plugs (detail subject to approval)
supplied by the Contractor before back-filling.
The ducts shall be water and vermin proof sealed, after completion of cable
installation.
6.10
CABLES INSTALLED IN CONCRETE TRENCHES
The cable trench system shall be designed by the Contractor to the approval of the
Employer. It shall be complete with removable covers and shall comply with the
building and civil works Section.
All cables routed in concrete trenches shall be suitably supported by means of
cleats or racks and raised from the trench floor by means of suitable spacers. All
SEC 06: Auxiliary Power & Control Cables
6/12
cables shall be run in a neat and orderly manner and the crossing of cables within
the trench shall not be acceptable without the prior approval of the Employer.
The Contractor shall be responsible for removing and replacing the trench covers
free of charge during the execution of his work as directed by the Employer.
6.11
CABLES SUPPORTED ON RACKS, TRAYS AND LADDERS.
6.11.1
General
All single core and multicore main power cables shall be installed in cleats or
saddles fixed at intervals. Multicore power cables shall be installed on trays, racks
or ladders but segregated from other cables on the same tray by a space of
300 mm.
All cables shall be installed on trays with adequate racks, clamps, cleats or ties to
avoid excessive sagging. The Contractor shall include for the preparation and
provision of single line cable routing drawings and detailed cable supporting
steelwork drawings, necessary to enable the Employer to give his approval for all
main and subsidiary routes before installation commences.
Ample allowance shall be made in the design for additional cabling for future
extensions.
Racks and trays shall be secured to channel or similar inserts installed in
accordance with Building and Civil works section.
All cables shall be run with a particular regard to neatness of appearance.
Multiple runs shall be arranged so that cables entering or leaving the run do so in
a logical manner.
Trays and supporting steelwork shall be securely bonded and grounded to the
main earthing/grounding system. Bonding and grounding connections shall be
adequate to carry prospective fault currents without exceeding thermal or voltage
limits.
6.11.2
Supporting Steelwork
All supporting steelwork shall be hot dip galvanised after manufacture and shall
be to the approval of the Employer.
Steelwork section shall not be less than 50 x 50 x 6 mm for steel channels and 50
x 50 x 5 mm for angles.
On all main cable runs, supporting structures shall be designed and drilled to
accommodate additional cable racks or cleats to the extent of 20% of cables
installed under the Contract and those required for known future extensions. The
spacing between supporting structures shall be not greater than 1m unless
otherwise approved by the Employer.
SEC 06: Auxiliary Power & Control Cables
6/13
In cases where cables or their supports must be fixed to structural metal work,
care shall be taken to avoid eccentric load transfer to beams or other structural
metal. Also, local overloading or deformation of structures shall be avoided. The
Contractor shall, if required, demonstrate that the loading resulting from the
attachment of cabling steelwork has been taken into account in the steelwork
design.
6.11.3
Cable Clamps, Cleats, Saddles and Ties
For single core cables carrying three phase alternating current, non-magnetic
trefoil cleats shall be used and for other single core and three core cables claw
type single or multicore unit cleats shall be used. The cleating arrangements for
single core cables shall be adequate to withstand all short circuit forces.
Cable clamps shall be used at any change of direction of cable laying, but at
agreed intervals on straight runs cable ties of approved design may be used.
Every non-flexible type cable shall be securely supported at a point not more than
1m from its terminal gland to prevent stressing the termination, and on vertical
runs passing through floors, immediately above the floor.
6.11.4
Trays, Racks and Ladders
The Contractor shall provide all necessary trays, racks or ladders which shall be
fixed at not more than 1m centers. On all main runs trays, racks or ladders shall
be installed to accommodate additional cables to the extent of 50% of those
installed under the Contract or known future requirements.
Cables shall be installed on trays, in general as follows:(a) Up to l6mm2- double layer touching.
(b)25mm2 to 70mm2- single layer touching.
(c) Above 70mm2- single layer with 25mm (minimum) spacing.
All cable trays shall be perforated.
All trays, racks and ladders shall be galvanised to a thickness not less than 1.6
mm and shall be PVC coated in exposed areas. The erection of steelwork, trays,
racks or ladders shall not proceed until the Employer's approval for such has been
obtained.
Where cables are run on trays, racks or ladders, they shall be tied to the tray at 1
m intervals using materials approved by the Employer.
The cable tray system shall have minimum of 20% spare cable capacity
throughout.
SEC 06: Auxiliary Power & Control Cables
6/14
6.12
TERMINATIONS
6.12.1
General
The Contractor shall be responsible for making all terminations, checking and
setting-to-work the completed installation. All cables provided as part of the
Contract shall be terminated at both ends.
For control wiring the cable tails shall be so bound that each wire may be traced
back to its associated cable without difficulty. Cores in twisted pairs or groups
shall be kept together. Any spare cores shall be numbered and terminated in the
spare terminals furthest away from the cable gland. All cables shall be long
enough to permit a second termination if necessary at a future date to the remotest
termination location in the panel.
Cable glands shall be used at all equipment to support the weight of cable from
the terminations and to seal the cable to the equipment, unless otherwise
approved by the Employer.
PVC, XLPE, silicone rubber and PTFE insulated cables shall be terminated via
glands to BS 6121. Glands where water may impinge on cables shall be type ElU,
with inner and outer seals and armour clamp. Unarmoured single core cables in
these areas shall have type A2 glands.
Glands in indoor locations with the exceptions as noted above shall be type C for
armoured cables and type A2 for unarmoured single core cables.
PVC shrouds shall be supplied and installed over each gland.
6.12.2
Power Cables
The Contractor shall ensure that the correct phase rotation and connections are
achieved. Particular care shall be taken in the case of heavy cables, where
subsequent correction may be difficult. Phase tests will be witnessed by the
Employer and, if found necessary, the Contractor shall carry out the reversal of
phase connections. Connections to electric motors shall be made as specified.
Where motors have tails rather than bushings, a heat shrink or equivalent PVC
tube for insulation of the crimp joint shall be provided.
Where insulated glands are provided, the Contractor shall ensure that the
insulation is maintained after jointing the cable and shall, if required, demonstrate
this to the satisfaction of the Employer.
The tails of two or three or four core cables in air insulated terminations shall be
identified by a band of approved tape of appropriate colour over the self-sealing
tape.
Single core cables shall be similarly identified by coloured tape over the cable
SEC 06: Auxiliary Power & Control Cables
6/15
beneath the gland.
6.12.3
Mineral Insulated Cables
The MICS cables shall be terminated with pot type seals in Universal ring type
glands utilizing cold plastic compound of an approved type. Accessories and
methods of anchoring the extension sleeving shall be to the approval of the
Employer. All MICS cable terminations shall be complete with high temperature
neoprene sleeves of sufficient length over conductors and sundries. All MICS
seals shall be tested not less than twenty-four hours after completion with a
1000V insulation resistance tester and a reading of greater than 10 Mohms must
be obtained before conductors are connected at any apparatus.
The Contractor shall provide the necessary compound of approved grade and
necessary MICS cable glands. Where the ambient temperature is expected to
exceed 50°C, special seals shall be used, details of which shall be approved by
the Employer.
6.13
TERMINATING AND JOINTING CONDUCTORS
Compression (indentation) type cable lugs and ferrules shall be provided and all
necessary tools, including dies and other materials for making compression joints,
shall be provided by the Contractor, who shall comply with the recommendations
of the supplier of cables and lugs in the preparation and execution of each
termination.
For stud type terminals approved crimping lugs shall be used.
Where clamp type terminals are used, the conductor shall be terminated without
lugs with the exception of flexible conductors having wires 0.3mm or smaller
which shall be fitted with crimps. Not more than one conductor shall be
terminated in each clamp.
6.14
CORE IDENTIFICATION
A uniform core identification system shall be used throughout the Station. The
following clauses outline the broad requirements but the exact implementation
shall be agreed with the Employer.
Approved numbered ferrules shall be supplied and fitted to every cable core of
control and instrument cables at each termination. The ferrules or sleeves shall be
of interlocking ring insulating materials such as plastic which shall be black
engraved on yellow background and have a glossy finish. The ferrules or sleeves
shall be unaffected by oil or damp. Identification marks on self - sticking cloth
shall not be used. The ferrules shall be of “O” or “D” cross section. Ferrules of
“C” type cross section shall not be used.
Single d.c. wires shall be identified by a red or blue coloured ring (positive or
negative polarity) followed by the identification of the polarity concerned
SEC 06: Auxiliary Power & Control Cables
6/16
(instrumentation, klaxon, alarm, etc.).
Direct a.c. circuits shall be identified by a yellow end piece followed by an
identification of the phase concerned.
Wiring for secondary circuits of voltage transformers shall be identified by a grey
end piece and wires in current transformer secondary circuits shall be identified
by a green end piece. This identification shall be completed by a terminal index.
All markings for terminal blocks, cables, cable conductors and wiring shall be
located on the corresponding fault finding drawing.
Characters suitably marked 'TRIP' in white shall be fitted on all wires associated
with trip circuits.
A common system of ferrule numbering shall be adopted such that ferrule
numbers at terminations shall agree with ferrule numbers on the internal wiring of
equipment.
6.15
CABLE IDENTIFICATION AND SCHEDULES
The Contractor shall prepare and submit computerized cable schedules, the
content and style of which shall be to the general approval of the Employer.
These shall include cable identification numbers for all cables except those
provided for lighting and small power circuits and those which are connected to
the load side of distribution boards for lighting and small power circuits.
The cable identification number system shall be such as to give a brief general
indication of the type and function of individual cables and shall be approved by
the Employer.
The Contractor may use a fully computerized system for rating, and routing of
cables, but shall provide a system that readily permits the cables to be scheduled
on the following basis in sequence of cable identification number:
(a) By cable identification number only
(b) By type and size of cables
(c) By function of cable
(d) By main LV ac and DC. Switchboard, actuator boards.
(e) By agreed electrical and mechanical plant functional groups.
The Contractor shall provide copies of the cable schedule in an approved format.
The Contractor shall provide a standard software package together with a suitable
personal computer to permit the Employer to access, display, print and edit the
schedules. The schedules shall be accessed by simple interactive dialogue using
'menu-selection' or other approved procedure.
In addition at agreed intervals the Contractor shall provide selected copies of the
above schedules in a computer print-out form.
SEC 06: Auxiliary Power & Control Cables
6/17
Each end of every cable, except those provided for lighting and small power
circuits and which are connected to the load sides of distribution fuse boards,shall
be identified with a separate cable reference number fitted in a suitable position
under the cable termination.
Where cables enter and leave ducts or pipes, suitable identification markers shall
be fitted.
The materials of the markers and fastenings shall be such as to avoid corrosion or
deterioration due to incompatibility of materials and shall ensure permanent
legibility.
6.16
INSPECTION AND TESTING
Inspection and testing during manufacture and after installation on site shall be in
accordance
with
Section
15
of
this
Specification.
SEC 06: Auxiliary Power & Control Cables
6/18
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 7
EARTHING SYSTEMS, ELECTRODES CONNECTIONS
SECTION7
EARTHING SYSTEMS, ELECTRODES CONNECTIONS
TABLE OF CLAUSES
7.1
SCOPE ..................................................................................................................
7/3
7.2
REFERENCES ..................................................................................................... 7/3
7.2.1 AMERICAN STANDARDS ......................................................................................................... 7/3
7.2.2 GERMAN STANDARDS ............................................................................................................ 7/3
7.2.3 BRITISH STANDARDS ............................................................................................................. 7/3
7.2.4 INTERNATIONAL STANDARDS ................................................................................................ 7/3
7.3
GENRAL ....................................................................................................................
7/4
7.4
EXTENT OF WORK ............................................................................................. 7/4
7.5
SOIL SURVEY ..................................................................................................... 7/4
7.6
FAULT CURRENT AND DURATION ................................................................ 7/5
7.7
EARTH ELECTRODE SYSTEM DESIGN ......................................................... 7/5
7.7.1 DESIGN CALCULATIONS ........................................................................................................ 7/5
7.7.2 EARTH ELECTRODE ............................................................................................................... 7/6
7.7.3 MESH SYSTEM ............................................................................................................................
7/6
7.7.4 INTERCONNECTED RODS ....................................................................................................... 7/6
7.7.5 OTHER CONDUCTORS ........................................................................................................... 7/7
7.7.6 REINFORCING STEEL ............................................................................................................. 7/7
7.7.7 CONDUCTORS OUTSIDE PERIMETER FENCE .......................................................................... 7/7
7.8
DESIGN OF EARTH SYSTEM ........................................................................... 7/8
7.8.1 EARTH SYSTEM ..................................................................................................................... 7/8
7.8.2 CONNECTION OF SYSTEM NEUTRALS AND EARTH................................................................. 7/8
7.8.3 MAIN EARTH BAR .................................................................................................................. 7/9
7.8.4 ELECTRICAL EQUIPMENT TANK AND STRUCTURE CONNECTIONS TO EARTH ........................ 7/9
7.8.5 CONNECTIONS TO NON-ELECTRICAL STRUCTURAL METALWORK AND EQUIPMENT ........... 7/10
7.9
MATERIALS AND INSTALLATION ............................................................... 7/10
7.9.1 CONDUCTORS .............................................................................................................................
7/10
7.9.2 EARTH RODS ..............................................................................................................................
7/10
7.9.3 FITTINGS ............................................................................................................................. 7/11
SEC 07: Earthing System, Electrodes Connections
7/1
7.9.4 JOINTS
............................................................................................................................. 7/12
7.10
EARTHING OF FENCES .................................................................................. 7/13
7.10.1 METHOD ...................................................................................................................................
7/13
7.10.2 SEPARATELY EARTHED FENCES ........................................................................................ 7/13
7.10.3 BONDED FENCES ............................................................................................................... 7/13
7.10.4 BONDING OF FENCE COMPONENTS ................................................................................... 7/13
7.10.5 GATES ............................................................................................................................. 7/14
7.10.6 POTENTIAL CONTROL OUTSIDE FENCES ........................................................................... 7/14
7.10.7 CONDUCTORS ...........................................................................................................................
7/14
SEC 07: Earthing System, Electrodes Connections
7/2
SECTION 7
EARTHING SYSTEMS, ELECTRODES CONNECTIONS
7.1
SCOPE
These clauses describe the General Requirements for the Earthing and Lightning
Protection and shall be read in conjunction with the Project Requirements and
Schedules.
7.2
REFERENCES
Any international standards referenced in the specifications and our outdated shall be
replaced with the corresponding replacement.
7.2.1
American Standards
ANSI/IEEE/std80IEEE Guide for Safety in AC Substation Grounding
ANSI/IEEE/std81IEEE Guide for Measuring Earth Resistivity, Ground
Impedance, and Earth Surface Potential of a Grounding
System
7.2.2
German Standards
DIN VDE 0141Earthing Systems for Power Installations with
Rated Voltages above 1 kV
7.2.3
British Standards
BS 1432
BS 1433
BS 2871
BS 2874
BS 4360
BS 6360:
BS 6651
BS 6746
BS 7430
7.2.4
Specification for copper for electrical purposes: high
conductivity copper rectangular conductors withdrawn or
rolled edges.
Specification for copper for electrical purposes. Rod
and bars
Specification for copper and copper alloys. Tubes
Specification for copper and copper alloy rods and
sections (other than forging stock).
Specification for weldable structural steel
Specification for conductors in insulated cables and
cords.
Protection of Structures against Lightning
Specification for PVC insulation and sheath of electric
cables.
Code of Practice for Earthing
International Standards
ISO 427
ISO 428
Wrought copper-tin-alloys - chemical composition and
form of wrought productions.
Wrought copper-aluminium alloys - chemical
SEC 07: Earthing System, Electrodes Connections
7/3
ISO 1187
ISO 1137
7.3
composition and forms of wrought production.
Special wrought copper alloys - chemical composition
and forms of wrought products.
Wrought coppers (having minimum copper contents of
99.85%) - chemical composition and forms of wrought
products.
GENERAL
An earthing system generally in accordance with the requirements of IEEE 80
and BS 7430 shall be designed under this Contract. Installation and the supply of
all materials and equipment shall also be included. The earthing system shall
include earth electrodes to provide the connection to the general body of the earth
and all conductors and connections to all electrical equipment and metallic
structures on the site. The earth electrodes shall limit the potential rise under fault
conditions and buried conductors shall be provided to limit potential differences
on the site and adjacent to the site to ensure safety to people and animals.
Protection for all electrical equipment against lightning shall also be provided.
7.4
EXTENT OF WORK
The Work under this Section comprises the site testing, design, supply and
installation, including excavation, backfilling and temporary reinstatement, of
earthing systems and connections to electrical apparatus at each substation. The
scope of work also includes earthing of substation building.
The Contractor shall be required to undertake all necessary earth resistivity tests
at the substation sites and, from these tests, to undertake the design of the earthing
systems. These designs, as well as providing safe passage to earth for the stated
earth fault currents, shall also include calculation of step, touch and mesh
potentials, which shall be within the allowable limits of the standards quoted in
this specification.
The design calculations of step, touch and mesh potentials, accompanied by full
installation drawings and material requirement schedules, shall be submitted to,
and receive the approval of, the Engineer before materials procurement or
installation commences.
7.5
SOIL SURVEY
The preliminary Bid design shall be based on a value of 100 ohm-m soil
resistivity.
Not later than one month after the site has been handed over for access, the
Contractor shall carry out an earth resistivity survey of the sites and report in
writing to the Engineer in accordance with the approved program The report shall
detail the methods and instruments used and the results of the surveys. Based on
the results the Contractor shall include in the report his proposals for the
resistivity to be used in the design of the earthing system.
SEC 07: Earthing System, Electrodes Connections
7/4
The surveys shall show the variation of resistivity across the site and with the
depth below the site. The Contractor shall consider if there is a need to model the
resistivity in two layers and if there is any advantage in the use of deep rod
electrodes.
The surveys shall also determine the depth and nature of any underlying rock,
which may limit the depth for driving earth rods or if boring will be necessary for
installing earth rods.
The weather conditions prior to and at the time of the surveys shall be recorded in
the report and an assessment made of the seasonal variations in resistivity based
on meteorological data for the area. The program for the project should, as far as
possible, time the resistivity surveys to take place during a dry season.
The report should also state if there are any indications that the ground is
corrosive to bare copper.
The report shall be approved by the Engineer before proceeding with the design
of the earthing system.
7.6
FAULT CURRENT AND DURATION
Each site shall be provided with an earth grid of buried conductors designed for
an earth fault current as specified in clause 1.4.1 of section-1 of this volume( 2 of
2). The preliminary earthing design shall be such that the potential rise shall not
exceed 5 kV.
7.7.
EARTH ELECTRODE SYSTEM DESIGN
7.7.1Design Calculations
The design of the earth electrode systems shall be based on the approved earth
resistivity data and the system fault currents and their duration.
The design calculations shall be to the approval of the Engineer and shall be
based on the methods given in the standards listed. The calculations shall include
the following parameters:(a) earth resistance of the whole system and of its components
(b)earth potential rise
(c) step, touch and mesh potentials inside and outside the perimeter fence
(d) requirements for a high resistance surface layer
(e) conductor ratings
Earthing points shall be provided such that the combined resistance of the earth
grid and all other earthing points does not exceed 0.5 ohm during the dry season.
The earth potential rises shall not exceed the CCITT limits appropriate to the
SEC 07: Earthing System, Electrodes Connections
7/5
classification of the system unless special precautions are taken to cater for
transferred potentials.
Step, touch and mesh potentials shall be within the permitted limits calculated in
accordance with the standards given in IEEE 80 for the proposed surface layer
7.7.2
Earth Electrode
The earth electrode shall comprise a system of bare conductors forming a mesh
buried near the surface of the ground and supplemented, if required, by one or
more of the following electrodes:(a) a system of interconnected rods driven into the ground
(b) a mesh system of bare conductors buried in the ground
(c) structural metalwork in direct contact with the ground
(d) reinforcing steel in buried concrete
(e) a system of bare conductors buried near the surface of the ground outside the
perimeter fence
7.7.3
Mesh System
The mesh system shall be designed in accordance with sub-clause 7.7.1 above to
limit touch, step and mesh potentials taking into account the combined length of
the mesh conductors, other buried conductors and rods but excluding any buried
conductors outside the perimeter fence. Due regard shall be given to non-linear
distribution of the fault current giving rise to the highest potentials at mesh
corners.
The rating of the mesh conductors shall be compatible with the fault currents after
allowing for parallel paths of hard drawn high conductivity copper strip with a
minimum conductor size of 150 mm2.
The conductor shall be installed in trenches excavated by the Contractor to a
depth of 500mm. The system will be installed after all foundations have been
laid and the site filled to 100mm below finished level. When the earthing grid has
been laid and backfilled, bricks will be laid up to finished site level. Where the
excavated material is rocky or may be difficult to consolidate, the backfilling
shall be carried out using other material to the approval of the Engineer. The cost
of such material shall be deemed to be included in the Contract.
7.7.4
Interconnected Rods
If the design calculations show that a mesh alone is unable to limit the potentials
to the required values, then the mesh shall be supplemented by the use of
interconnected earthing rods driven into the ground or installed in bored holes.
Rods shall be installed inside the perimeter fence to enclose the maximum
possible area compatible with the earthing of any metallic fence. (The spacing
between rods shall not be less than their length, unless rating considerations
SEC 07: Earthing System, Electrodes Connections
7/6
determine otherwise). The copper rod electrodes of 15mm diameter shall be
interconnected in groups of four to eight rods by insulated copper conductors and
non-ferrous clamps to form a ring. Each group shall be connected to the mesh by
duplicate insulated copper conductor via disconnecting test links.
Individual rods may be connected directly to the mesh, provided the rod can be
disconnected for testing.
Rods installed in bored holes may be used to reach lower resistivity ground strata
at depths beyond the reach of driven rods or where rock is encountered and it is
not possible to drive rods. After installing the rod, the bored hole shall be
back-filled with a low resistivity liquid mixture, which shall not shrink after
pouring, to ensure good contact between the rod and the ground for the life of the
installation.
The resistance and rating of individual rods and the combined resistance of the
groups of rods in the proposed design shall be calculated and the rating of the
interconnecting conductors shall not be less than that of the group of rods with a
minimum conductor size of 75mm2.
The calculation of potentials in the design of the complete installation shall be
made without the group of rods with the lowest estimated resistance to simulate
the condition with the group disconnected for testing.
7.7.5
Other Conductors
As an alternative to rods to supplement a mesh, additional bare copper conductors
with a cross-section area of not less than 150 mm2 may be used. They shall be
buried in the ground within the perimeter fence to enclose the maximum possible
area compatible with the earthing of any metallic fence. Such conductors may be
laid below the mesh, below foundations or in areas where there is no plant. It
shall be shown by calculation that the step potentials are low in such areas.
The conductor shall be in a ring, or a part of a ring, with at least two widely
separated connections to the mesh or other parts of the earthing system.
7.7.6
Reinforcing Steel
The reinforcing steel in the foundations of buildings containing the primary
electrical equipment may be used as auxiliary electrodes, subject to the approval
of the Engineer. The Contractor shall show in the design calculations that the
fault currents and D.C. stray currents will not damage the structure.
Steel reinforcing mesh in the floors of the building may also be used for the
control of step and touch potentials within the building, subject to the approval of
the Engineer.
7.7.7
Conductors Outside Perimeter Fence
SEC 07: Earthing System, Electrodes Connections
7/7
If the design calculations show that the step and touch potentials outside the
perimeter fence or wall exceed the limits, then additional bare conductors shall be
buried in the ground outside the fence in the form of rings encircling the whole
site.
The distance of the conductors from the fence and the depth shall be determined
in the design to ensure that step and touch potentials are within the limits.
The minimum conductor size shall be 75 mm2 copper and shall be connected to
the fence or the mesh with 75 mm2 conductors at each corner of the site and at
intervals of not more than 100 m. These conductors shall not be included in the
calculations called for above.
7.8
DESIGN OF EARTH SYSTEM
7.8.1
Earth System
An earth system shall comprise the following components: (a) the conductors between the earth electrode system and the main earth bar
(b) the main earth bar
(c) the conductors between the main earth bar and the metallic frames,
enclosures or supports of electrical equipment
(d)the conductors between structural metalwork and non-electrical equipment and
the main earth bar
The rating of earth system conductors connected between an item of electrical
plant and the earth electrode system shall be sufficient to withstand the fault
currents and duration, after allowing for the parallel paths through the earth
system conductors, with any one conductor disconnected.
The design of earth system shall take into account the corrosiveness of the soil
based on the soil survey.
The design comprising all the above mentioned items shall be submitted to the
Engineer for approval within four months of the award of Contract.
7.8.2
Connection of System Neutrals and Earth
The system neutral points within a substation shall have duplicate connections to
the closest link chamber of an earthing point.
The earth electrodes of a neutral earthing point shall be arranged in two groups
with a conductor from each group to a test link and there shall be duplicate bare
copper conductors of cross sectional area not less than 150 mm2 from each test
link to the earth grid. The duplicate connection may be in the form of a ring.
Neutral earthing connections between the substation system (transformer) neutral
and the test links shall be of bare copper tape, secured and supported on stand-off
SEC 07: Earthing System, Electrodes Connections
7/8
insulators so that there is no contact between copper tape and transformer tank.
Neutral earthing conductors shall normally be buried directly in the ground but
where necessary, they may be cleated to walls, fixed to cable racks or laid in the
cable trenches.
7.8.3
Main Earth Bar
The main earth bar shall be in the form of a ring or rings of bare conductors
surrounding, or within, an area in which items to be earthed are located. Where
two or more rings are installed, they shall be interconnected by at least two
conductors which shall be widely separated.
The main earth bar, or parts thereof, may also form part of the earth electrode
system, providing this is bare conductor.
Each main earth bar shall be connected by at least two widely separated
conductors to the earth electrode system.
The minimum conductor size for the main earth and interconnections between
earth bars and the earth electrode system shall not be less than 150 mm2.
7.8.4
Electrical Equipment Tank and Structure Connections to Earth
Connections between: (a) all HV electrical equipment and (b) LV electrical
equipment comprising substantial multi-cubicle switchboards and the main earth
bar shall be duplicated. The bare copper conductor size shall have a minimum
cross section area of 150 mm2.
All substation equipment, including disconnectors, earth switches, main
transformer tanks, current and voltage transformer tanks, switchgear and
electrical supporting steelwork, etc. shall all be connected with the earth grid.
Surge arresters installed for the protection of transformers shall be connected by
low reactance paths both to the transformer tanks and to the earth grid.
An earth mat shall be installed at all operating positions for outdoor HV
equipment manual operating mechanism boxes and local electrical control
cubicles to ensure the safety of the operator. The mat shall be directly bonded to
the cubicle and the conductors forming the mat and the bonding connection shall
have a minimum copper cross-section area of 75 mm2.
Galvanized structures comprising bolted lattice components shall not be used as
the sole earth connection path to post and strain insulators.
Buildings containing electrical equipment shall be provided, at each level, with a
ring of earthing conductors which shall have duplicate connections to the earth
grid outside the building. The frames of all switchgears, control and relay panels
and other electrical equipment and exposed structural metal work shall be
SEC 07: Earthing System, Electrodes Connections
7/9
connected by branches to a ring. The ring and branch conductors shall be of the
same material as the earth grid. Strip run within buildings, inside cable trenches
or above ground level on apparatus shall be neatly supported in non-ferrous
clamps.
Connections between other LV electrical equipment and the earth bar need not be
duplicated. The single conductor shall be rated to withstand the fault rating of the
equipment.
7.8.5
Connections to Non-Electrical Structural Metalwork and Equipment
All metalwork within the project area which does not form part of the electrical
equipment shall be bonded to the main earth bar except where otherwise
specified. The bonding conductor size shall be not less than 150 mm2.
Individual components of metallic structures of plant shall be bonded to adjacent
components to form an electrically continuous metallic path to the bonding
conductor.
Small electrically isolated metallic components mounted on non-conducting
building fabric need not be bonded to the main earth bar.
7.9
MATERIALS AND INSTALLATION
7.9.1
Conductors
Conductors shall be of high conductivity copper in the form of circular
conductors stranded to IEC 60228 or solid rods or bars to BS1433.
Conductor sheaths shall be of PVC to meet the requirements of BS 6746 Grade
TM1 or IEC 60502 Grade ST1 with a minimum thickness of 1.5 mm.
Buried conductors which are not part of the earth electrode system shall be PVC
sheathed circular stranded cable.
Bare strip conductors only shall be used for earth electrodes or voltage control
meshes.
Conductors buried in the ground shall normally be laid at a depth of 500 mm in
an excavated trench. The backfill in the vicinity of the conductor shall be free of
stones and the whole backfill shall be well consolidated. Conductors not forming
part of a voltage control mesh shall be laid at the depth required by the approved
design and, in the case of PVC sheathed conductor, at the same depth as any
auxiliary power or control cables following the same route.
All conductors not buried in the ground shall be straightened immediately prior to
installation and supported clear of the adjacent surface.
7.9.2
Earth Rods
SEC 07: Earthing System, Electrodes Connections
7/10
Earth rods shall be driven to a depth below the ground water table level, to be
determined by the Contractor during soil investigation and survey of site.
The earth rods shall be of hard-drawn high conductivity copper with a diameter of
not less than 15 mm with hardened steel driving caps and tips. The rods should
be as long as possible but couplings may be used to obtain the overall depth of
driving required by the design.
The rods shall be installed by driving into the ground with a power hammer of
suitable design to ensure the minimum of distortion to the rod. Where it is not
possible to drive rods to the full depth required due to the presence of a strata of
rock, then holes shall be drilled or blasted in the rock. The holes shall be filled
with bentonite or other approved material prior to inserting the rod.
If difficult driving conditions arising from hard or rocky ground are encountered
or are anticipated or there is a need for deep rods, then high tensile steel rods shall
be used. High tensile steel rods shall have a molecularly bonded high
conductivity copper coating with a minimum radial thickness of not less than 0.25
mm. The overall diameter shall be not less than 12 mm. Rolled external screw
threads shall be used on the rods for coupling and after rolling the thickness of the
copper coating on the threaded portion shall be not less than 0.05 mm.
Rods, driving caps and tips shall abut at couplings to ensure that the couplings
and screw threads are not subject to driving forces. All screw threads shall be
fully shrouded at the couplings. Alternatively, conical couplings may be used to
the approval of the Engineer.
High conductivity copper for earth rods shall have a minimum copper content
(including silver) of 99.90% to ISO 1337, Cu-ETP or Cu-FRHS (BS 2894 Grade
C101 or C102) for copper earth rods and to ISO 1337 Grade Cu-ETP (BS 28734
Grade C101) for the molecular bonded copper coating of steel rods.
The steel for copper-clad steel rods shall be low carbon steel with a tensile
strength of not less than 570 N/mm2 to ISO 630, Grade Fe 430A (BS 4360,
Grade 43A) or better.
Couplings for copper rods shall be of 5% phosphor bronze
(copper-tin-phosphorous) to ISO 427, CU Sn4 (BS 2874, Grade PB 102M) and
for copper bonded steel rods of 3% silicon or 7% aluminum bronze to BS 2874,
Grade CS 101 and BS 2871, Grade CA 102.
7.9.3
Fittings
Clips for supporting strip conductors not buried in the ground shall be of the
direct contact type and clips for circular conductors shall be of the cable saddle
type. The clips shall support the conductors clear of the structure.
Conductors shall be connected to earth rods by a bolted clamp to facilitate
removal of the conductor for testing the rod.
SEC 07: Earthing System, Electrodes Connections
7/11
Disconnecting links shall comprise a high conductivity copper link supported on
two insulators mounted on a galvanised steel base for bolting to the supporting
structure. The two conductors shall be in direct contact with the link and shall not
be disturbed by the removal of the link. Links for mounting at ground level shall
be mounted on bolts embedded in a concrete base.
Disconnecting links mounted at ground level and the connections at the earth rods
shall be enclosed in concrete inspection pits, with concrete lids, installed flush
with the ground level.
All conductor fittings shall be manufactured from high strength copper alloys
with phosphor bronze nuts, bolts, washers and screws. Binary brass copper alloys
will not be acceptable. All fittings shall be designed for the specific application
and shall not be permanently deformed when correctly installed.
Sheathed conductor support fittings may be of silicon aluminium, glass-filled
nylon or other tough non-hygroscopic material for indoor installations.
Fittings not in direct contact with bare or sheathed conductors may be of hot-dip
galvanised steel.Bi-metallic connectors shall be used between conductors of
dissimilar materials and insulating material shall be interposed between metallic
fittings and structures of dissimilar materials to prevent corrosion.
7.9.4
Joints
Permanent joints shall be made by exothermic welding below ground, or
crimping for above ground connections.
Detachable joints shall be bolted and stranded conductors at bolted joints shall be
terminated in exothermically welded lugs or a crimped cable socket. The diameter
of any holes drilled in strip conductors shall not be greater than half the width of
the strip.
Connections to electrical equipment shall be detachable and made at the earthing
studs or bolts provided on the equipment by the manufacturer. When an earthing
point is not provided, the point and method of connection shall be agreed with the
Engineer.
Connections to metallic structures for earthing conductors and bonding
conductors between electrically separate parts of a structure shall be either by
direct exothermic welding or by bolting using a stud welded to the structure.
Drilling of a structural member for a directly bolted connection shall only be
carried out to the approval of the Engineer.
Bolted joints in metallic structures, including pipe work and which do not provide
direct metallic contact, shall either be bridged by a bonding conductor or both
sides of the joint shall be separately bonded to earth, unless the joint is intended
SEC 07: Earthing System, Electrodes Connections
7/12
to be an insulated joint for cathodic protection or other purposes.
When the reinforcing in concrete is used as a part of the earthing system, the
fittings used to provide a connection point at the surface of the concrete shall be
exothermically welded to a reinforcing bar. This fitting shall be provided with a
bolted connection for an earthing conductor. The main bars in the reinforcing
shall be welded together at intervals to ensure electrical continuity throughout the
reinforcing.
No connections shall be made to reinforcing bars and other steelwork which do
not form part of the earthing system and are completely encased in concrete.
7.10
EARTHING OF FENCES
7.10.1 Method
Metallic fences shall be separately earthed unless they come within 1.8m of any
equipment or structure above the surface of the ground and which is connected to
the main earthing system. If the separation of 1.8m cannot be obtained, the fence
shall be bonded to the main earthing system.
7.10.2 Separately Earthed Fences
The earthing of a fence shall be provided by connecting certain metallic fence
posts to an earth rod by a copper conductor. The earth rod shall be driven adjacent
to the posts inside the fence line to a depth of not less than 3.0m. Where no
metallic posts are provided, the earth rods shall be connected directly to the metal
wires, mesh or other components of the fence.
If, owing to the nature of the ground, it is not possible to drive earth rods, then
fence posts shall be connected to the centre point of a 20 m length of bare copper
conductor buried in the ground at a depth of 500 mm, running closely parallel to
the inside of the fence.
The earth rods or bare conductor electrodes shall be installed at each corner post,
below the outer phase conductors of overhead line connections passing over the
fence, at each gate and at intervals of not more than 100 m.
7.10.3 Bonded Fences
Fences which need to be bonded to the main earthing system of the installation
shall be connected by copper conductors to the nearest accessible point on the
main earthing system at each point where the fence comes within 1.8 m of any
electrical equipment. Bonds shall also be made to each corner post, below the
outer phase conductors of overhead line connections passing over the fence, at
each gate and at intervals of not more than 100 m.
7.10.4 Bonding of Fence Components
SEC 07: Earthing System, Electrodes Connections
7/13
Fences made up of bolted steel or other metallic components do not require
bonding between components.
Where such fences have non-metallic
components, bonds shall be installed to maintain continuity between metallic
components. Reinforced concrete components shall be treated as being
non-metallic.
Longitudinal wires for supporting other fence components, or for anti-climbing
guards and the wires of chain link shall be directly bonded to each fence earth
electrode or to each bond to the main earthing system.
Metallic components on masonry, brick, concrete or similar boundary wall shall
be treated in the same manner as metallic fences.
Wire fence components coated for anti-corrosion protection shall be earthed in
accordance with this Clause.
7.10.5 Gates
The fixed metallic components on both sides of the gate shall be directly bonded
together by a copper conductor installed under the surface of the access way.
Flexible conductors shall be installed to bond the moving parts of the gates to the
metallic fixed parts. An earth rod or a bond to the main earthing system shall be
installed at each gate.
7.10.6 Potential Control Outside Fences
Where the approved design calculations show that the touch or step potentials
outside the fence or boundary wall would otherwise be excessive, bare copper
conductors shall be buried in the ground outside the fence or boundary wall at
such depths and spacings as are shown in the approved design calculations to give
acceptable touch and step potentials. The conductors shall form complete rings
surrounding the installation and each ring shall be bonded to the adjacent ring and
to the fence at each corner, at each gate and at intervals of not more than 100 m.
In this case separate earth electrodes are not required for the fences.
If the boundary fence or wall is substantially non-metallic, the rings of conductors
shall be bonded to the main earth system at each corner of the site and at intervals
of not more than 100 m. Any metallic components on such boundary fences or
walls shall be bonded to the earthing system in accordance with this
Specification.
If the boundary fence is metallic and is not within 1.8 m of any part of the main
earthing system or equipment bonded thereto, the fence and outer conductor rings
shall not be connected to the main earthing system unless the approved design
calculations show otherwise.
Any meshes formed by bonding the outer conductors to the main earthing system
shall be sub-divided by additional conductors, if required, to give acceptable
touch, step and mesh potentials.
SEC 07: Earthing System, Electrodes Connections
7/14
7.10.7Conductors
All conductors used for earthing and bonding the fences and components and for
outer rings shall have a cross-sectional area of not less than 75 mm2.
SEC 07: Earthing System, Electrodes Connections
7/15
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 8
BATTERIES, CHARGERS AND DC DISTRIBUTION SWITCHGEAR
SECTION8
BATTERIES, CHARGERS AND DC DISTRIBUTION SWITCHGEAR
TABLE OF CLAUSES
8.1 SCOPE ...................................................................................................... 8/3
8.2 REFERENCES ......................................................................................... 8/3
8.2.1 IEC STANDARDS .................................................................................................................... 8/3
8.2.2 BRITISH STANDARDS ............................................................................................................. 8/3
8.3 DESIGN REQUIREMENTS ..................................................................... 8/3
8.3.1 GENERAL8/3
8.4 BATTERIES.............................................................................................. 8/4
8.4.1 TYPE OF BATTERY ................................................................................................................. 8/4
8.4.2 INITIAL CHARGE AND TEST DISCHARGE................................................................................ 8/4
8.4.3 BATTERY DUTY ..................................................................................................................... 8/4
8.4.4 LOCATION OF BATTERIES ...................................................................................................... 8/5
8.4.5 BATTERY MOUNTING CONNECTIONS AND ACCESSORIES ....................................................... 8/6
8.5 CONTROL AND CHARGING EQUIPMENT ........................................... 8/7
8.6 DISTRIBUTION SWITCHBOARDS....................................................... 8/10
8.7 LABELLING ........................................................................................... 8/11
8.8 SPECIAL TOOLS ................................................................................... 8/12
8.9 INSPECTION AND TESTING ............................................................... 8/12
SEC 08: Battery, Charger and DC Distribution
8/1
SEC 08: Battery, Charger and DC Distribution
8/2
SECTION 8
BATTERIES, CHARGERS AND DC DISTRIBUTION SWITCHGEAR
8.1
SCOPE
These clauses describe the General Technical Requirements for Batteries, Chargers
and DC distribution switchgear for use in substations for 110V DC power for
switchgear operations, protection, control, alarms, indications and emergency
lighting.
The equipment shall be supplied, installed and commissioned as per instruction and
approval of the engineers.
8.2
8.2.1
REFERENCES
Any international standards referenced in the specifications and our outdated shall
be replaced with the corresponding replacement.
IEC Standards
IEC 60051
Direct acting indicating analogue electrical measuring instruments
and their accessories.
IEC 60146
Semiconductor converters
IEC 60146-1-1Basic requirements of electrical power converters
IEC 60146-1-3Transformers and reactors
IEC 6060529 Degree of protection provided by enclosures
IEC 60439
Low voltage switchgear and control gear assemblies (BS EN 60439)
IEC 60623
Vented nickel cadmium prismatic rechargeable single cells
8.2.2
British Standards
BS 88
BS 381C
BS 5634
BS 6231
Cartridge fuses for voltages up to and including 1000 VAC and
1500 V DC.
Specification for colours for identification coding and special
purposes.
Method of Test for Potassium Hydroxide.
Specification for PVC insulated cables for switchgear and
controlgear wiring.
8.3
DESIGN REQUIREMENTS
8.3.1
General
Batteries shall be located in separate mechanically ventilated rooms, which will be
provided with sinks and water supplies. Storage facilities will be provided for
electrolyte, distilled water and maintenance equipment.
The voltage measured at the main distribution switchgear shall not vary by more
than plus 10 percent or minus 20 percent of the nominal voltage under all charging
conditions when operating in accordance with the requirements of this Section.
SEC 08: Battery, Charger and DC Distribution
8/3
The complete equipment shall preferably be a manufacturer’s standard but any
departure from this Specification shall be subject to the approval of the Engineer.
8.4
BATTERIES
8.4.1
Type of Battery
The battery shall be of the high performance Nickel Cadmium pocket plate type
complying with IEC 60623 and shall be designed for a life expectancy of 25 years.
Battery cases shall be of high impact translucent plastic or annealed glass and shall
be indelibly marked with maximum and minimum electrolyte levels. The design of
the battery shall permit the free discharge of the gases produced during the normal
operating cycle, whilst excluding dust. Spray arresters shall be included.
The electrolyte shall be free from impurities and the Potassium Hydroxide used
shall comply with BS 5634. Dilution of the alkaline electrolyte and topping up of
cells shall be carried out using distilled water only.
A complete set of test and maintenance accessories, suitably boxed, shall be
provided for each battery. A syringe hydrometer and a durable instruction card
shall be included in each set.
Cells shall be numbered consecutively and terminal cells marked to indicate
polarity.
Cells shall be permanently marked with the following information:
-
Manufacturer's reference number and code
Year and month of manufacture
Voltage and nominal capacity at the 5 hour discharge rate
The electrolyte capacity and general design of the cells shall be such that
inspection and maintenance, including topping up of the electrolyte, shall be at
intervals of not less than twelve months.
8.4.2
Initial Charge and Test Discharge
The initial charge, test discharge and subsequent re-charge of the battery must be
carried out under continuous supervision. Resistors, instruments, leads, and the
other apparatus will be necessary for the initial charge, test discharge and
subsequent recharge of the battery.
8.4.3
Battery Duty
The battery shall have sufficient capacity to supply the following continuous and
intermittent loads for the periods specified, with the chargers out of service.
SEC 08: Battery, Charger and DC Distribution
8/4
Standing DC loading for protection, control, indications and alarms for 10 hours.
This loading shall be determined from all equipment to be supplied on this
Contract. In addition the future circuit requirements estimated on the same basis as
the present requirements.
At the end of 5 hours the battery shall have sufficient capacity to complete the
operations listed below, at the end of which duty the system voltage shall not have
dropped below 90 percent of the nominal voltage with the standing loads, specified
above, connected.
1.
Two closing operations on all circuit breakers (including future) supplied by
the battery.
2. Two tripping operations on all circuit breakers (including future) supplied by
the battery. Where busbar protection is provided, it shall be assumed that all
circuit breakers in any one busbar protection zone trip simultaneously.
3.
Charging of DC motor wound circuit breaker closing springs (where
applicable) to enable the closing operations to be carried out.
4.
At the end of these duties, the battery voltage shall not have dropped such that
the voltage at the battery terminals falls below 90% of the nominal system
voltage when supplying the standing load.
5.
In addition, the voltages at the terminals of all components in the system (eg.
relays, trip and closing coils) shall not be outside of the individual voltage
limits applying to them.
6.
A margin of 10 % shall be allowed for derating of this battery over its life
time.
All quantities derived in this manner shall be quoted in the Bid, but shall not be
used for ordering materials until specifically approved by the Engineer. Detailed
calculations, and loading characteristics on which these are based, shall be
submitted to the Engineer at an early stage.
8.4.4
Location of Batteries
The batteries shall be housed in a ventilated battery room. The charging equipment
and distribution switchboards shall be housed in a separate room.
The floor of the battery room shall be coated with a suitable electrolyte resistant
protective coating. The floor shall be fitted with a drain and shall have sufficient
slope to prevent any major electrolyte spillages from entering into other areas.
No ducts or any other items shall penetrate the floor or create a means whereby
spillage can drain away apart from the drain provided for this purpose.
The ventilation fans and lamps in battery room shall be an explosion proof type.
SEC 08: Battery, Charger and DC Distribution
8/5
8.4.5
Battery mounting connections and accessories
Batteries shall be placed on timber boards mounted in double tiers on steel stands
of robust construction and treated with acid resisting enamel or gloss paint to BS
381C No.361. The cells shall be arranged so that each cell is readily accessible for
inspection and maintenance and it shall be possible to remove any one cell without
disturbing the remaining cells. The stands shall be mounted on insulators and be so
dimensioned that the bottom of the lower tier is not less than 300mm above the
floor.
Alternatively, batteries may be mounted in a similar manner on treated
hardwoodstands.
Batteries shall be supplied and erected complete with all necessary connections and
cabling. Connections between tiers, between end cells and between porcelain wall
bushings shall be by PVC cables arranged on suitable racking or supports. Before
jointing, joint faces shall be bright metal, free from dirt, and shall be protected by a
coating of petroleum jelly. Terminal and intercell connections shall be of high
conductivity corrosion free material.
Cartridge fuses shall be provided in both positive and negative leads, positioned as
close to the battery as possible and shall be rated for at least three times the
maximum battery discharge current at the highest operating voltage. The two fuses
shall be mounted on opposite ends of the battery stand or rack in an approved
manner. These fuse links shall comply with BS 88 Clause DC. 40 and shall be
bolted in position without carriers.
Warning labels shall be fitted to warn personnel of the danger of removing or
replacing a fuse whilst the load is connected and that fuses should not be removed
immediately following boost charge due to the possible ignition of hydrogen gas.
Fuses between the battery and charger shall be located adjacent to the battery in a
similar manner to that described above. A warning label shall be placed on the
charging equipment indicating the location of these fuses and the fact that they
should be removed to isolate the charger from the battery.
It shall not be possible to leave the battery disconnected (by means of switches or
removal or operation of fuses) without some local and remote indication that such a
state exists.
One set of miscellaneous equipment, including two syringe hydrometers, one
cell-testing voltmeter, two cell-bridging connectors, two electrolyte-pouring
funnels, two electrolyte thermometers, battery instruction card for wall mounting,
electrolyte airtight containers, labels, tools and other items necessary for the
erection and correct functioning and maintenance of the equipment, shall be
provided for each station.
SEC 08: Battery, Charger and DC Distribution
8/6
8.5
CONTROL AND CHARGING EQUIPMENT
Each battery charging equipment shall comply with the requirements of BS 4417
(IEC 146), shall be of the thyristor controlled automatic constant voltage type with
current limit facilities and shall be suitable for supplying the normal constant load,
at the same time maintaining the battery to which it is connected in a fully charged
condition. All equipment shall be naturally ventilated.
All the equipment for each charger shall be contained in a separate ventilated steel
cubicle. The charger cubicles shall normally be mounted immediately adjacent to
the DC distribution panel to form a board and shall be of matching design colour
and appearance.
Where their ratings permit, chargers shall preferably be designed for operation
from a single-phase AC auxiliary supply with a nominal voltage of 230 V.
Otherwise a three phase 400V supply may be utilised. Chargers shall maintain the
float charge automatically for all DC loads between 0 and 100%, irrespective of
variations in the voltage of the ac supply within the following limits :
-
Frequency variation : 47 to 51 Hz.
Voltage variation : ± 15%
The mains transformer shall be of a suitable rating and design. Clearly marked
off-circuit tappings shall be provided on the primary windings and change of
tapping shall be by means of easily accessible links. The transformer shall be of the
natural air-cooled type capable of operating continuously at full load on any
tapping with the maximum specified ambient temperature.
All rectifiers and semi-conducting devices employed in the charger shall be of the
silicon type. They shall be adequately rated, with due regard to air temperature
within the charger enclosure, for the maximum ambient temperature.
The rating of the charger on float charge shall be equal to the normal battery
standing load plus the recommended finishing charge rate for the battery.
Each charger shall also incorporate a boost charge feature which shall, after having
been started, provide an automatically controlled high charge rate sufficient to
restore a fully discharged battery to the fully charged state within the shortest
possible time without excessive gassing or any form of damage to the battery. The
boost charge shall be initiated manually or automatically upon detection of a
significant battery discharge.
An adjustable timer shall be provided to
automatically switch the charger to the float condition after the correct recharge
period.
Should the AC supply fail while a battery is on boost charge, the switching
arrangements shall automatically revert the charger to float charge status and then
reconnect the battery to the distribution board.
The output voltage regulator shall be adjustable for both float and boost charge
SEC 08: Battery, Charger and DC Distribution
8/7
modes, within limits approved by the Engineer, by means of clearly marked
controls located inside the cubicle.
Although it is not intended that the charger be operated with the battery
disconnected, the design of the charger shall be such that with the battery
disconnected the charger will maintain the system voltage without any damage to
itself and with a ripple voltage no greater than 2.0% rms of the nominal output
voltage.
The charger shall automatically adjust the charging current from a value not less
than the battery capacity divided by 10 hours to a minimum value of not more than
the battery capacity divided by 200 hours. The charging circuitry shall be so
designed that the failure of any component will not give a situation which will
cause permanent damage to the battery by over charging.
Each charger shall have a float charge maximum current rating sufficient to meet
the total standing load current on the dc distribution board plus a battery charging
current equal numerically to 7% of the battery capacity at the 10 hour rate.
Each charger shall be designed with a performance on float charge such that with
the output voltage set at approximately 1.45 V per cell at 50% load and rated input
voltage and frequency, the output voltage shall not vary by more than plus 3% to
minus 2% with any combination of input supply voltage and frequency variation as
stipulated in this Specification and output current variation from 0-100% of rating.
Each charger shall be suitable for operating alone or in parallel with the other
charger. When operating with both chargers, one charger shall be arranged to
supply the standing load with the second charger in the quiescent standby mode.
Each charger shall also have a taper characteristic boost charging facility which
shall be selectable by a float/boost charge selection switch and which will give
boost charging of 1.60 - 1.75 volts per cell.
Each charger shall be designed with a performance on boost charge such that with
rated input voltage and frequency the charger output shall not be less than its rating
in Watts at 1.3 V and 1.65 V per cell, and also the output voltage shall be 1.60 1.75 V per cell over an output range of 0 - 100% of rating.
The boost charging equipment shall be capable of recharging the battery within six
hours following a one hour discharge period.
In the event of the battery becoming discharged during an AC supply failure, the
rate at which recharging commences shall be as high as possible consistent with
maintaining the automatic charging constant voltage feature and with the
connections remaining undisturbed as for normal service.
The charger shall have an automatic boost/quick charge feature, which shall
operate upon detection of a significant battery discharge. When, after a mains
failure, the AC supply voltage returns and the battery have been significantly
SEC 08: Battery, Charger and DC Distribution
8/8
discharged, the charger will operate in current limit. If the current limit lasts for
more than a specified time and the charging current does not fall back to float
level, the automatic high rate charge shall be activated.
An override selector switch shall be provided inside the charger unit to enable a
first conditioning charge to be made, in line with the battery manufacturer’s
recommendations, for batteries which are shipped dry and require forming at site.
A diode voltage regulator(DVR) unit shall be incorporated in the output circuit of
each charger to limit the load voltage during charging of the battery. Should the
stabilizer fail in the boost charging mode, the charger shall automatically revert to
the float mode.
An anti-parallelling diode shall be provided in each positive feed to the DC
distribution board to prevent faults on one supply affecting the other. These diodes
shall be continuously rated to carry the maximum possible discharge current likely
to occur in service and a safety factor of 4 shall be used to determine the repetitive
peak reverse voltage rating. The I2t rating of the diodes shall be such that in the
event of a DC short circuit, no damage to the diodes shall result.
Each charger shall be capable of sustaining, without damage to itself, a continuous
permanent short circuit across its output terminals. The use of fuses, MCBs or
other similar devices will not be acceptable in meeting this requirement.
Suitable relays shall be provided for each charger to detect failure of the incoming
supply and failure of the DC output when in float charge mode. These relays shall
operate appropriate LED on the respective charger front panel and shall have
additional voltage free contacts for operating remote and supervisory alarms.These
alarms shall be immune from normal supply fluctuations and shall not be initiated
when any one charger is taken out of service.
The charger shall also be fitted with a device to de-energise the charger in the event
of a DC output float over voltage.
Each charger shall be provided, as a minimum, with the following instrumentation,
indication and alarm facilities:-
LED for the AC supply to the rectifier and DC supply from the rectifier.
LED for float and boost charging operations.
Voltmeter - Input voltage.
Voltmeter - Output voltage.
Ammeter - Output current.
Alarm - Charger failure.
Alarm - Mains failure.
The following battery alarms shall also be provided:
-
Battery fuse failure
Diode assembly failure
SEC 08: Battery, Charger and DC Distribution
8/9
-
Battery circuit faulty
Low DC volts
High AC volts
Earth fault +ve
Earth fault -ve
Lamp test facilities shall be included.
A “charger faulty” alarm for each charger and a “battery faulty” alarm shall be
provided in the substation control room and to the SCADA system where
applicable.
Each battery charger shall be equipped with charge fail detection equipment to give
local indication and remote alarm if the voltage from the charger falls below a
preset level which will be lower than the nominal float charge voltage. Suitable
blocking diodes shall be provided to prevent the battery voltage being supplied to
the equipment and so prevent charge fail detection.
The device shall not operate on switching surges or transient loss of voltage due to
faults on the AC system.The voltage at which the alarm operates shall be
adjustable for operation over a range to be approved by the Engineer.
Each charger shall be equipped with a switch-fuse for the incoming AC supply and
an off load isolator for the DC output.
Bidders shall include particulars with their bid on the method of adjustment
included to compensate for ageing rectifier elements. The construction of the
charger shall be such that access to all components is readily available for
maintenance removal or replacement.Internal panels used for mounting equipment
shall be on swing frames to allow for access to the charger interior.
A battery earth fault detecting relay, which will centre tap the system via a high
resistance, shall be incorporated in the charger panel.
A low voltage detecting device for the system shall be incorporated in the charger
panel. No-volt relays will not be accepted for these devices. The voltage setting
shall be adjustable over an approved range.
In addition to any other requirements specified elsewhere, the battery earth fault
detecting relays and low voltage devices shall each have three alarm contacts, one
for local visual annunciation, one for the station control panel alarm indication and
one for potential free contact for external supervisory alarms.A lamp test facility
shall be provided.
8.6
DISTRIBUTION SWITCHBOARDS
The switchboard shall comply with the requirements of BS 5468 (IEC 60439)
SEC 08: Battery, Charger and DC Distribution
8/10
The distribution switchboard shall be of the cubicle type or otherwise incorporated
in the cubicles for battery chargers. Double pole switches and fuses or switch fuses
(miniature circuit breakers to BS 4752 or IEC 60127 may only be used if it can be
shown that there will be no discrimination problems with sub-circuits) shall be
fitted to the DC switchboard as required by substation services but, as a minimum
requirement, that set out in the Schedule A of Requirements.
Distribution panels shall be mounted adjacent to the charger control panel and shall
be of the cubicle type complying with the general requirements of cubicle type
control panels. No equipment associated with the chargers shall be installed in the
distribution board.
Distribution panels shall incorporate double-pole switches and fuses for each of the
outgoing DC circuits and double-pole isolators for the incoming DC supplies. The
panel shall be provided with a voltmeter and centre zero ammeter on each
incoming circuit.
A double pole switch or contactor shall be provided for the purpose of
sectionalizing the busbar.
Connections between the battery and the distribution cubicle shall be made in PVC
insulated cable as required. Cable laid in runs where it may be subject to damage
shall be protected by wire armouring, be sheathed overall and be cleated to walls as
required.
Cable boxes or glands shall be provided as appropriate for all incoming and
outgoing circuits of the distribution switchboard and associated battery chargers.
Each circuit shall be suitably labelled at the front of the panel and at the cable
termination where the terminals shall be additionally identified.
Charging and distribution switchboards shall be provided with an earthing bar of
hard drawn high conductivity copper which shall be sized to carry the prospective
earth fault current without damage or danger.
The cubicles for the chargers and distribution boards shall be of rigid, formed sheet
metal construction, insect and vermin proof, having front facing doors allowing
maximum access to the working parts, when open. The design of the cubicles for
the chargers shall be such as to prevent the ingress of dust and minimize the spread
of flames or ionised zones, shall be to IEC 60529 IP52, but at the same time shall
provide all necessary ventilation and cooling. The design of the frames shall allow
the clamping and holding of all chokes, transformers and similar sources of
vibration, so that vibration will be minimized, satisfy relevant standards, and not
limit the life of the equipment. The frame shall allow the fixing of lifting and so
that the equipment remains properly mechanically supported whilst being
transported, lifted and installed.
8.7
LABELLING
All relays, instruments and control devices, and each unit of the equipment, shall
SEC 08: Battery, Charger and DC Distribution
8/11
be provided with a label. All labels and lettering shall be of sufficient size to
provide easy reading from the normal operating or maintenance positions and shall
consist of black lettering on a white background. All warning and danger labels
shall have white lettering on a red background. Labels shall be of the noncorrodible type and lettering shall be of motorway script or similar. If plastic labels
are used, these shall be laminated to avoid warping.
8.8
SPECIAL TOOLS
The Contractor shall provide a complete set of all special tools and services
necessary for the erection and maintenance of the complete equipment.
8.9
INSPECTION AND TESTING
Inspection and testing during manufacture and after installation on site shall be in
accordance
with
Section
15
of
this
Specification.
SEC 08: Battery, Charger and DC Distribution
8/12
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 9
LV AC DISTRIBUTION SWITCHGEAR
SECTION9
LV AC DISTRIBUTION SWITCHGEAR
TABLE OF CLAUSES
9.1SCOPE
............................................................................................................................... 9/3
9.2 REFERENCES ....................................................................................................................... 9/3
9.3 SWITCHBOARD DESIGN ..................................................................................................... 9/3
9.3.1 GENERAL ............................................................................................................................... 9/3
9.3.2 RATING ............................................................................................................................... 9/4
9.3.3 BUSBARS ............................................................................................................................... 9/4
9.3.4 BUSBAR AND CIRCUIT SHUTTERS .......................................................................................... 9/4
9.3.5 CIRCUIT LABELS.................................................................................................................... 9/5
9.4
CIRCUIT BREAKERS ......................................................................................... 9/5
9.5
SWITCH-FUSES .................................................................................................. 9/5
9.6
OIL FILTRATION SOCKET OUTLET AND PLUG .......................................... 9/6
9.7
INSPECTION AND TESTING ............................................................................ 9/6
SEC 09: LVAC Distribution Switchgear
9/1
SEC 09: LVAC Distribution Switchgear
9/2
SECTION 9
LVAC DISTRIBUTIONSWITCHGEAR
9.1
SCOPE
These clauses describe the General Technical Requirements for LVAC
switchboards for supplies to “Substation Services” including lighting and
GIS building/control building services (Section 10).
9.2
REFERENCES
Any international standards referenced in the specifications and our outdated shall be
replaced with the corresponding replacement.
IEC60044
IEC 60269
IEC 60439-1
IEC 60644
IEC 60898
Instrument Transformers
Low Voltage Fuses
Specification for low voltage switchgear and control gear assemblies
Specification for high-voltage fuse links for motor circuit applications
Electrical Accessories - Circuit-breakers for overcurrent protection for
household and similar installations
IEC 60947-1Low-voltage switchgear and Control Gear
- General
IEC 60947-2Low-voltage switchgear and Control Gear
- Circuit-breakers
IEC 60947-3Low-voltage switchgear and Control Gear
Switches,
disconnectors and
fuse combination
units
IEC 60947-4Low-voltage switchgear and Control Gear
- Electromechanical
Contactors and motor starters
9.3
SWITCHBOARD DESIGN
9.3.1
General
Main switchboards and MCB sub-distribution boards for substation and building
supplies will be constructed to IEC 439, (BS EN 60439) in accordance with the
following:
The classification of the main switchboards shall be:
(a)
The external design of switchboards shall be of the multi-tier, multicubicle type.
(b)
Installation shall be indoors.
(c)
Switchboards shall be free standing and fixed to the floor.
(d)
Enclosures degree of protection shall be not less than IP42.
SEC 09: LVAC Distribution Switchgear
9/3
(e)
Switchboards shall be of metal clad construction.
(f)
All instrumentation and metering shall be fixed to a hinged lockable
compartment.
(g)
Switchboards and all associated equipment shall be suitable for use on a
400/230 volt, three phase, four wires, and 50 Hz system having the neutral
solidly earthed.
(h)
Each circuit shall be clearly labelled to show the destination of the
associated cable and the “ON” and “OFF” positions of the switches.
(i)
Distribution boards for exterior use shall be galvanised, weatherproof and
to category IP55 degree of protection.
The equipment shall be of the single busbar type with circuit equipment housed in
separate compartments.
Where two or more incoming circuit breakers are provided at substations, these
shall be mechanically and electrically interlocked to prevent more than one circuit
closing at the same time.
The enclosures of all switchboards shall be dustproof and vermin proof. Access
doors shall be mounted using concealed hinges. All removable covers shall be
fitted with captive screws. Anti-condensation heaters with control switches shall
be provided on switchboards. They shall be suitable for a tropical climate.
9.3.2
Rating
Incoming supplies to all switchboards shall be protected at the point of supply.
All switchboards shall be suitably rated for a prospective short-circuit breaking
capacity of 15 kA at 400V for three seconds.
9.3.3
Busbars
Busbars shall be capable of carrying the full rated current continuously without
exceeding the maximum temperature specified in IEC 60439 under site ambient
conditions.
Busbars shall be of copper, individually covered with a heat resistant phase
coloured PVC. Busbar links between panels shall not be used. Neutral busbars
shall have the same cross sectional areas as the phase busbars. Busbars shall be of
the same current rating throughout their length and shall be capable of extension
at both ends with the minimum disturbance to the busbar and cubicle enclosure.
9.3.4
Busbar and Circuit Shutters
For drawout equipment shutters shall be provided over busbar and circuit orifices
to close automatically and positively when the equipment is isolated or
SEC 09: LVAC Distribution Switchgear
9/4
withdrawn. Means shall be provided for padlocking the sets of shutters. Busbar
orifice shutters shall be painted signal red and labelled ‘BUSBAR’ in white
letters. Circuit orifice shutters shall be painted lemon yellow.
One blanking cover of each size shall be provided to prevent access to a circuit
compartment when the equipment has been completely withdrawn from the
panel.
9.3.5
Circuit Labels
Approved type title labels are to be fitted externally on the front cover of each
distribution board giving details of the points controlled by each circuit. The
circuit list shall be typed or printed stating the location of the equipment served,
rating of the protective unit and the circuit loading. The lists shall be mounted on
the inside of the cover door and shall be protected by an acrylic sheet slid into a
frame over the circuit list, the list and cover to be easily removable to permit
circuit modifications.
9.4
CIRCUIT BREAKERS
All MCB and MCCB circuit breakers shall be high speed fault limiting,
thermal/magnetic type with quick break, trip free mechanisms which prevent the
breaker being held in against overloads or faults, shall comply with IEC 60947
and be fitted with overcurrent releases of both thermal and instantaneous type.
Short circuit performance shall be to IEC 60947.
Where circuit breakers incorporate thermal overload protection and short-circuit
protection, their settings shall be subject to agreement with the Engineer.
Tripping arrangements shall be such as to ensure simultaneous opening of all
phases. Arc extinction shall be by de-ionising arc chutes.
Circuit breakers on the incoming circuits shall have facilities for locking in the
“off” position.
The fault interrupting capacity of the circuit breaker shall not be less than that of
the switchboard itself, or if this is not the case, back up fuses shall be included.
9.5
SWITCH-FUSES
Each switch-fuse unit shall be housed in a separate metal compartment and
provided with a hinged metal door, interlocked with the switch mechanism so
that:
(a)
The door cannot be opened whilst the switch is closed.
(b)
The door, on opening, automatically locks the switch in the “off” position.
Facilities shall be incorporated to allow for the deliberate release of this
interlock for maintenance purposes, should it be desired to observe the
SEC 09: LVAC Distribution Switchgear
9/5
switch in operation.
An insulating barrier shall be fitted to segregate the fuses and neutral link from
the switch and the connections of the latter shall be effectively shielded by an
inner metal screen when the compartment door has been opened to obtain access
to the fuses.
The switch-fuses may be either of the combination fuse-switch type or of the type
with the switch and fuse in separate units. In either case, interlocking shall be
provided to prevent access to the fuses until the associated switch is opened and
provision shall be made for padlocking the switch in the “on” and “off” positions.
The switch shall have a quick make and quick break action, independent of the
speed at which the switch handle is operated, and shall be entirely suitable for
switching the inductive loads associated with motor circuits.
9.6
OIL FILTRATION SOCKET OUTLET AND PLUG
The Contract shall include heavy duty weatherproof three phase and neutral
interlocked switched socket outlets and plugs suitable for supplying the
transformer oil filtration units.
9.7
INSPECTION AND TESTING
Inspection and testing during manufacture and after installation on site shall be in
accordance
with
Section
15
of
this
Specification.
SEC 09: LVAC Distribution Switchgear
9/6
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 10
BUILDING AND CIVIL ENGINEERING WORKS
SECTION10
BUILDING AND CIVIL ENGINEERING WORKS
TABLE OF CLAUSES
10.1
GENERAL ...................................................................................................... 10/3
10.1.1 SCOPE OF WORK ................................................................................................................ 10/3
10.1.2 CONTRACTOR TO SATISFY HIMSELF AS TO ALL CONDITION .............................................. 10/4
10.1.3 WAYLEAVES, LAND PURCHASE AND PLANNING PERMISSION ........................................... 10/4
10.1.4 SITE SURVEY DRAWINGS ................................................................................................... 10/5
10.1.5 EARTH WORKS .................................................................................................................. 10/5
10.1.6 ENGINEER'S AND EMPLOYER'S ACCOMMODATION/SURVEYING EQUIPMENT .................... 10/5
10.1.7 PROGRAMME...................................................................................................................... 10/5
10.1.8 MONTHLY PROGRESS CERTIFICATES/PROGRESS REPORTS ............................................... 10/6
10.1.9 TEMPORARY FACILITIES .................................................................................................... 10/6
10.1.10 SITE SUPERVISION .......................................................................................................... 10/6
10.1.11 DESIGN AND DRAWINGS .................................................................................................. 10/7
10.2
REFERENCES ................................................................................................... 10/7
10.2.1 GENERAL ........................................................................................................................... 10/7
10.2.2 DESIGN AND CONSTRUCTION STANDARDS ........................................................................ 10/7
10.3
DESIGN .............................................................................................................. 10/8
10.3.1 ARCHITECTURAL AND STRUCTURAL REQUIREMENTS OF BUILDINGS................................ 10/8
10.3.2 CABLE BASEMENT ........................................................................................................... 10/11
10.3.3 CABLE TRENCHES ........................................................................................................... 10/11
10.3.4 GROUND CONDITIONS, FOUNDATIONS AND SITE INVESTIGATION .................................. 10/12
10.3.5 FIRE CRITERIA ................................................................................................................ 10/16
10.3.6 DRAINAGE ....................................................................................................................... 10/17
10.3.7 SURFACING ...................................................................................................................... 10/18
10.3.8 ROADS ........................................................................................................................... 10/18
10.3.9 WATER SUPPLY ............................................................................................................... 10/19
10.3.10 PLUMBING AND SANITARY FITTINGS ............................................................................. 10/20
10.3.11 SUBSTATION BUILDING FLOORS ................................................................................... 10/20
10.3.12 CABLE BASEMENT AND GIS ROOM FLOORS .................................................................. 10/21
10.3.13 CONTROL ROOM FLOOR ................................................................................................ 10/21
10.3.14 BATTERY ROOM FLOORS ............................................................................................... 10/22
10.3.15 SITE CLEARANCE, OBSTRUCTIONS AND ADJACENT STRUCTURES ................................. 10/22
10.3.16 GUARD HOUSE AND FENCES ......................................................................................... 10/23
10.3.17 WINDOWS ...................................................................................................................... 10/23
10.3.18 DOORS ........................................................................................................................... 10/24
Sec 10: Building & Civil Engineering Works
10/1
10.3.19 BRICKWORK ................................................................................................................... 10/25
10.3.20 EXPANSION JOINTS, JOINT FILLERS AND SEALANTS .................................................... 10/25
10.3.21 CABLE TRENCHES IN SWITCHYARDS ............................................................................. 10/26
10.3.22 RAINWATER PIPES ......................................................................................................... 10/26
10.3.23 SWITCHYARD FOUNDATIONS ......................................................................................... 10/27
10.3.24 TRANSFORMER BASES ................................................................................................... 10/27
10.3.25 BLAST WALLS ................................................................................................................ 10/28
10.3.26 PAINTS AND PAINTING .................................................................................................. 10/28
10.3.27 FURNITURE ................................................................................................................... 10/29
10.3.28 CONCRETE ..................................................................................................................... 10/29
10.3.29 CONCRETE REINFORCEMENT ........................................................................................ 10/30
10.3.30 EXTERNAL RENDER ....................................................................................................... 10/31
10.3.31 LIFTING BEAMS ............................................................................................................. 10/31
10.3.32 STAIRS ........................................................................................................................... 10/31
10.4
CONCRETE WORKMANSHIP ....................................................................... 10/32
10.4.1 GENERAL ......................................................................................................................... 10/32
10.4.2 AGGREGATES ................................................................................................................... 10/32
10.4.3 SAMPLING........................................................................................................................ 10/32
10.4.4 GRADING ......................................................................................................................... 10/33
10.4.5 CEMENT........................................................................................................................... 10/33
10.4.6 WATER ........................................................................................................................... 10/33
10.4.7 REINFORCING .................................................................................................................. 10/33
10.4.8 STORAGE ......................................................................................................................... 10/33
10.4.9 DESIGN MIX .................................................................................................................... 10/34
10.4.10 MIXING AND PLACING OF CONCRETE ............................................................................ 10/35
10.4.11 TESTING OF CONCRETE ................................................................................................. 10/36
10.4.12 FORMWORK ................................................................................................................... 10/37
10.4.13 REINFORCING STEEL ..................................................................................................... 10/38
10.4.14 CONSOLIDATION OF CONCRETE .................................................................................... 10/38
10.4.15 CURING OF CONCRETE .................................................................................................. 10/38
10.4.16 HOT WEATHER CONCRETING ........................................................................................ 10/39
10.5
WORKMANSHIP OF ALL OTHER MATERIALS ......................................... 10/40
APPENDIX A ................................................................................................... 10/41
Sec 10: Building & Civil Engineering Works
10/2
SECTION 10
BUILDING AND CIVIL ENGINEERING WORKS
10.1
GENERAL
Under this Section the Contractor will be responsible for the design and
construction of all civil engineering and building works and services for all new
132/33 kV AIS Substation and Extension of existing 132/33kV AIS substation.
10.1.1
Scope of Work
The Bid must cover all requirements of the bid documents and any other items not
specifically mentioned but which are necessary for the satisfactory design,
construction, operation and maintenance of all equipment to the satisfaction of the
Employer. No additional costs will be considered for any items which have been
overlooked but which are essential for the proper completion of the project in every
respect.
The work shall include but not be limited to:
a) Site survey and subsoil investigation.
b) Site preparation, cutting or filling up to the level specified in 10.1.4 and
leveling.
c) Roadways, car ports, paths and surfacing.
d) Foundations for all equipment to be installed in outdoor switchyards, control
building, indoor switchgear and any other building required for the project.
e) Control building (complete building consisting of structural reinforced
concrete frames, brick walls, concrete roof and floor slabs) with cable
basement
f) Floor finishing, Nitocote epoxy resin coating in battery room, raised floor for
control room and homogeneous tile for other floors.
g) Cable trenches, cable tunnels, cable ducts and pipe ducts.
h) Water supply and plumbing installations
i) Surface water and foul drainage.
j) Guard house and fences.
k) Air conditioning and ventilation.
l) Lighting, small power, external floodlighting, emergency lighting and fire
protection.
m) Renovation of existing control building if required
n) extension/renovation of existing security boundary wall, security fence, cable
trenches, internal/access roads, drainage system if required.
For all substations and for individual rooms in substations suitable nameplates,
signs and labels shall be provided to ensure identification, safe operation of plant
and warning of danger. The text, which shall be both in Bangla and English, shall
be approved by the Employer. The substation sign board(s) shall be 3 mm,
Aluminum sheet powder coated and the text (Bangla & English) shall be UV
resistant, PGCB logo on a separate circular plate to be fixed at the centre of sign
board. The inscriptions shall be engraved with colored lettering. All nameplates,
Sec 10: Building & Civil Engineering Works
10/3
signs and labels shall be non-deteriorating and non-warping under aggressive
weather conditions and shall be guaranteed for a minimum period of 10 years.
Plates, etc., will be securely attached using bolts and nuts or screws; adhesive will
not be permitted.
Included in the scope of work is the detailing, construction and maintenance of the
following items which shall generally be constructed to the Employer’s standards
but full working drawings shall be prepared by the Contractor:
a) Septic tank and soakaway
b) Underground water storage tank
Drawing and design of septic tank and soakaway shall be prepared by the
contractor and shall be finalized during detailed Engineering.
The Bidder shall state which approved local building contractor(s) he proposes to
employ to carry out the work.
10.1.2
Contractor to satisfy himself as to all conditions
The Contractor shall assess:
a) access conditions at all sites, plus ground conditions and ground bearing
capacity
b) transport costs, materials costs and restrictions of availability of supply of
materials locally
c) importation restrictions and delay due to customs controls
d) restrictions imposed by existing equipment on sequence of construction,
access, etc.
e) restrictions caused by cable laying, equipment and line contractors
f) ground conditions and temporary works required to provide support during
excavation
10.1.3
Wayleaves, Land Purchase and Planning Permission
The Employer will be responsible for the acquisition of all land required for
substation site. The Employer will also be responsible for obtaining land to provide
a permanent single access to each site from a nearby road or waterway. During the
construction period the Contractor shall be responsible for maintaining this access
in a reasonable condition by reinstating damage caused by his construction traffic
and Employer traffic. The Contractor shall perform the land development of the
planned area with filling the soil approximately from the existing ground level
(ocular observation by the employer) or above 1 meter from the HFL. The Bidder
shall include the cost of land development in the Bid Price based on the volume of
land developmentindicated in the Price Schedule, the payment amount of land
developmentshall be adjusted based on the actual volume of work.
Should the Contractor require more than one single access to a site or require
additional land for construction activities outside the permanent site boundary, he
shall be responsible for the purchase or wayleave of the required land.
Sec 10: Building & Civil Engineering Works
10/4
The Employer will be responsible for applying for planning permission. The
Contractor shall be responsible for completing the approved site survey and the
approved site layout plan, together with the approved architectural elevations of all
facades of any buildings, by the key date given in the programme for each site so
that the Employer may use these drawings to apply for planning permission.
10.1.4
Site Survey Drawings
For each site the Contractor shall prepare a survey at 1:200 scale showing existing
ground levels on a minimum 10 meter grid and details of all features above and
below the ground within the site boundary and up to 15 meters beyond it by the
key date stated in the program Levels shall be related to bench marks clearly
indicated on the plan. The plan shall be submit to approval by the Employer and
the agreed substation building floor levels shall be given on each site plan. The
Contractor shall propose the building floor level to the Employer. The final site
level shall be 500mm above the nearest public road.
10.1.5
Earth Works
The Contractor shall be deemed to have included in the Contract Sum for providing
a level or uniform sloping site to suit his substation layout design. The final soil
levels (i.e. the level below the brick surfacing) shall be stated on the site survey
plan.
All fill shall be compacted in layers not exceeding 150mm deep. The Compaction
of the developed land shall nowhere be less than 90% of the maximum dry density
10.1.6.1 Engineer’s and Employer’s Accommodation/Surveying Equipment
On each major site the Contractor shall provide an office of approx size 5 x 8m
equipped with desk, 2 chairs, light, fan and air conditioner for the sole use of the
Employer’s Engineer and his inspectors. Similar facilities are to be provided for the
supervision consultant of the Employer.
10.1.6.2 Surveying Equipment
The Contractor shall loan his surveying instruments to the Engineer and his staff
when required. Instrument checks shall be carried out at monthly intervals.
10.1.7
Program
The Contractor's program shall at Bid stage define the following key dates for each
site. Where drawings are to be submitted for approval, they shall be submitted at
least 6 weeks before the key dates to allow for the Engineer to comment and his
comments to be incorporated in the drawings:
a) Issue of approved site survey drawing complete with soil levels and floor
levels
Sec 10: Building & Civil Engineering Works
10/5
b)
c)
d)
e)
Issue of approved electrical layout drawings
Completion of Site Investigation field work
Issue of approved Site Investigation Final report
Completion of loading tests on a foundation on each fill site and any other site
where settlement is likely to be a problem
f) Issue of approved drawings required for Planning Permission
g) Issue of a full complete set of civil building drawings
h) Construction start date
i) Date access will be given for:
- Installation of equipment in Buildings
- Installation of outdoor plant
j) Construction finish date
The Contractor's program shall outline the number of sites he proposes to build at
any time and shall show the order of completion of sites and how crews will move
from site to site. This information shall be used to establish the number of
expatriate site supervisors required.
The drawing program shall ensure that complete set of approved civil building
drawings will be issued at least 21 days before construction start at any site, in
accordance with the Project Requirements.
The Construction program shall be expressed in an 'S' curve for the whole project,
with the percentage (of the total value of work in the schedules) given for each site
each month. The overall percentage completion of the project each month shall
also be given.
10.1.8
Monthly Progress Certificates/Progress Reports
In accordance with the Project Requirementsthe Contractor shall submit agreed
progress certificates for each site before the seventh day of the next month. These
certificates shall state the percentage completion of each item in the schedules and
shall state the overall percentage completion of each site and that site’s
contribution to overall project percentage completion. An updated ‘S’ curve shall
be submitted with the progress certificates.
10.1.9
Temporary Facilities
The Contractor shall provide all temporary buildings, workshops, cement and lime
stores and latrines required for his use. The Contractor shall agree the location of
these buildings with the Employer, after submitting a drawing showing their
proposed location.
When a Contractor is placed in possession of a site, or part of a site, he shall erect
temporary fencing immediately to protect the site until the boundary wall shall be
erected.
10.1.10
Site Supervision
Sec 10: Building & Civil Engineering Works
10/6
Although the civil and building works may be let as a sub-contract to an approved
local contractor, the main contractor shall ensure that an expatriate supervisor in
his direct employ is continuously available at each site during construction. This
supervisor shall have at least a working command of spoken English and be able to
read, understand and discuss specifications and drawings.
The Contractor shall notify the Employer in writing of every concrete pour and
foundation casting the day before the work starts. This is a Hold Point.
10.1.11
Designs and Drawings
The Contractor shall obtain the Employer’s approval for the use of all design codes
and standards before design work starts. All design and drawing work shall be
completed in the Contractor's own country, in direct co-ordination with the
electrical plant design.
The Contractor shall supply one copy of all of codes for the Employer in Dhaka. If
non-English equivalent National codes are adopted, the Contractor shall supply
English translations of these Codes to the Employer.
One copy of calculations shall be submitted together with drawings. To avoid
possible misunderstandings, calculations will not be approved separately from
drawings.
The Contractor shall generally submit a complete set of drawings for each
substation for approval after initially getting the electrical layout of each substation
approved. Where possible, drawings shall be standardized and general drawings
(00) issued covering several sites.
For each substation the Contractor shall provide a co-ordination plan at scale 1:200
showing structure types, foundation types, cable trenches, roads, ducts, buildings,
boundary walls, earthing, drainage and all services in this Contract.
10.2
REFERENCES
10.2.1
General
The design and construction shall conform to the latest edition of the relevant
Codes and Standards. Any proposed substitution for the listed Standards by an
equivalent Standard will be subject to approval by the Employer. Relevant
Standards include, but are not limited to, those listed in sub section 2.2 below. Any
international standards referenced in the specifications and our outdated shall be
replaced with the corresponding replacement.
10.2.2
Design and Construction Standards
BS 12
BS EN 124
BS 812
Portland Cement
Gully and Manhole tops for vehicular and pedestrian areas
Testing aggregates
Sec 10: Building & Civil Engineering Works
10/7
BS 882
Aggregates from natural sources for concrete
BS 1377
Methods of test for soils for civil engineering purposes
BS 1722: Part 10 Anti-intruder fences
BS 1881
Testing concrete
BS 2853
Design and testing of overhead runway beams
BS 3148
Methods of test for water for making concrete
BS 3921
Clay bricks
BS 4449
Steel bars for the reinforcement of concrete
BS 5262
External renderings
BS 5395
Stairs, ladders and walkways
BS 5572
Sanitary pipe work
BS 5628
Code of practice for use of masonry
BS 5930
Code of practice for site investigations
BS 6031
Code of practice for earthworks
BS 6367
Code of practice for drainage of roofs and paved areas
BS 6399: Part 1
Code of practice for dead and imposed loads
BS 6399: Part 2
Code of practice for wind loads
BS 6465
Sanitary installations
BS 6651
Code of practice for protection of structures against lightning
BS 6700
Design, installation, testing and maintenance of services supplying
water for domestic use
BS 8004
Code of practice for foundations
BS 8005
Sewerage
BS 8100
Lattice towers and masts
BS 8102
Code of practice for protection of structures against water from the
ground
BS 8110
Structural use of concrete
BS 8206
Lighting for buildings
BS 8215
Code of practice for design and installation of damp-proof courses
in masonry
BS 8290
Suspended ceilings
BS 8301
Code of practice for building drainage
10.3
DESIGN
10.3.1
Architectural and Structural Requirements of Buildings
All new buildings shall be designed to be architecturally pleasing in appearance and
to withstand the tropical climate with minimal maintenance.
Architectural elevations of all elevations of buildings shall be agreed before other
detail plans are prepared.
Air conditioning units shall be provided in rooms listed in Section 13. Air conditioned
rooms shall have a false ceiling such that the overall thermal transmittance of the roof
shall be below 0.45 Watts/m2˚C . The false ceiling shall be made from non
combustible materials, and shall be easily removable to provide easy access to small
power cables.
Sec 10: Building & Civil Engineering Works
10/8
All buildings shall be reinforced by a reinforced concrete frame which shall be
capable of resisting a horizontal earthquake force of 0.2G. An external concrete open
staircase shall be provided up to the roof. The roof shall be a flat insitu concrete slab
designed for 2.5 kN/m2 live load. A fixed ladder of galvanised steel shall be provided
up to the roof.
The roof shall be waterproofed with lime terracing 2:2:7 lime, shurki (powdered
brick) and brick chips 0.75" down, which shall be beaten in accordance with local
practice. The entire roof area shall be laid in one continuous operation. The minimum
compacted thickness of terracing shall be 25mm at the low points of the roof with a 1:
150 slope to those points formed by a layer of terracing of increasing thickness. Once
laid, the terracing shall be covered with a layer of bitumen emulsion and the edge of
the terracing shall be protected against erosion into the downpipes. Downpipes shall
be 100mm diameter cast iron pipe placed outside the wall but shall be enclosed in a
facing brick buttress. There shall be at least one downpipe per 100m2 of roof. The
Contractor shall guarantee the roof against leaks for a period of 3 years from the
Taking Over Certificate date. The roof shall project at least 450mm beyond the face
of all walls to form a sunshade and rain shelter to the walls below. The upper surface
of this projection shall be sloped and a drip provided.
The main entrance to all buildings shall be shaded, either by a projection of the roof
over the entrance verandah or by a separate roof at a lower level. This area of roof
shall also be lime terraced and drained by rainwater pipes.
The roof parapet wall shall be about 0.8 metre high with an insitu concrete coping
with DPC below it. Where facing bricks are used below the roof level, they shall also
be used above roof level. An architectural feature shall be provided by panels of open
decorative blockwork (Mirpur ceramics or similar approved) to ensure good air
circulation over the roof. Air bricks shall be provided at 750 mm centres in solid
portions of parapet wall.
The head of each downpipe shall be fitted with an enlarged hopper and purpose made
cast iron grill set into a recess in the roof projection.
Window openings shall be fitted with protruding concrete sunshades above and at the
sides of the openings.
All external walls shall be first class brickwork plus a 50mm thick layer of Mirpur
Ceramics facing bricks or similar approved, or rendered with cement render and
painted as required by the architectural plan. The internal walls shall also be generally
of 105mm thick first class brickwork. Internal walls shall all be rendered and receive
one sealer coat plus two finishing coats of emulsion paint. All brickwork shall be tied
into the concrete frame by galvanised ties. Externally, rendered walls shall receive
primer plus two finishing coats of PEP acrylic external quality paint or similar
approved. At least two air bricks shall be provided to each room in which staff
work/rest.
Sec 10: Building & Civil Engineering Works
10/9
Particular attention must be given in the design of buildings and layouts to fire
prevention and safety of personnel at all times. Buildings housing switchgear and
control equipment shall be designed as far as practicable to exclude pollution under
all likely weather conditions. Fire-proof or flame-retarding materials are to be used
for floor, wall and ceiling finishes. Where areas are designed as having a fire
resistance rating then materials shall be shown to have passed approved standard tests
for that class of fire resistance.
The height of rooms housing control equipment shall provide about 1 metre clearance
over the top of the cabinets to the underside of the false ceiling. In the switchgear
rooms, about 1 metre clearance shall be provided over the switchgear to the underside
of the roof slab but the Contractor shall provide a greater clearance if it is required to
remove equipment. The clearance maybe reduced below downstand beams provided
no equipment is required to be removed from the top of the switchgear. All rooms in
any building shall be one height.
Rooms shall have walls and roof slabs adequately insulated. Maximum thermal
transmittance values for all rooms shall be 0.7 watts/m2/°C for walls and 0.57 for roofs. Air
conditioning units shall be provided in rooms listed in Section 13. Air conditioned
rooms shall have a false ceiling such that the overall thermal transmittance of the roof
shall be below 0.45 Watts/m2/°C. The false ceiling shall be made from non
combustible materials, and shall be easily removable to provide easy access to small
power cables. Suspended ceilings, with acoustic tiling and incorporating lighting and
air-conditioning fixtures shall be used in corridors, offices, control and SCADA
rooms of the buildings and as per schedule of finishes
All structures shall be designed to carry the loads imposed by the structure itself,
together with live loads in accordance with an approved standard or code of practice.
The roof shall be designed for 2.5 kN/m2 live load.
All doors opening outwards from the buildings shall be provided with panic latches or
bolts which override any locking device, for escape in the event of fire. All doors
shall be provided with overhead door closuers of adequate capacity. Door labels
incorporating electrical hazard warning in Bangla and English shall be fixed to each
entry door. Vision panels shall be provided to frequently used doors.
Window openings shall be fitted with protruding concrete sunshades above and at the
sides of the openings.
Float operated submersible pump of capacity 25 cum/hour at a head of 8 meters to be
provided for sump of basement. The pumps shall be fixed in all respect ready for
operation and discharge into stormwater drainage system.
The domestic water supply system shall include all plumbing, underground pipework,
high and low level storage tanks, valves, fittings and pumps (including the provision
of a standby pump) for the provision of a pressurized water supply system for the
static water tank and all buildings within the compounds.
Sec 10: Building & Civil Engineering Works
10/10
On completion of the installation and prior to putting to use, the system shall be
sterilized in accordance with an approved Code of Practice.
The Contractor shall be responsible for the provision and installation of a water
supply serving the substation buildings. Every cistern, sink, basin, etc., shall be
provided with as stop-cock in the supply pipe adjacent to the fitting. Each basin, sink
and shower unit is to be provided with both hot and cold water. Provision shall be
made for connection to the drinking water supply.
Toilets shall be provided with 1 no. western type WC, 1 no. Asiatic type WC, 1 no.
wash-hand basin, 1 no. wall mounted mirror. All necessary fittings and accessories
shall be provided.
Battery rooms shall be supplied with sink and drainer.
Control buildings housing switchgear and control equipment shall include a cable
basement to facilitate connection to the equipment. Basements shall be constructed so
as to protect the building substructure from water in accordance with BS 8102.
10.3.2 Ground Conditions, Foundations and Site Investigation
(a) Fill Sites
Fill will be placed by the Contractor. On fill sites where the depth of fill exceeds
3 metres the Contract assumes piled foundations shall be installed below
buildings. If piled foundations are found to be unnecessary in the Final Site
Investigation Report, a reduction in Contract value shall be agreed on the basis of
schedule rates.
Piles shall be concrete (cast insitu or precast) complying with BS 8004.
On every fill site the Contractor shall prove that his switchyard foundation will
not suffer settlement greater than 20 mm by constructing a foundation and load
testing this to twice the design bearing pressure for a minimum of 20 days.
Outdoor equipment shall be provided with spread footings. The bearing capacity
of proposed soil level for outdoor equipment shall be checked by the Plate
Bearing Test. The Contractor will be provided by the Employer with a survey of
soil levels prior to filling. The Contractor shall impose the site layout on the
survey to check for uneven depth of fill below any foundation and where uneven
depth of fill exists his foundation proposals shall restrict final differential
settlement to a 1 in 400 slope.
If a fill site has not been exposed to one wet season before foundation work
starts, the Contractor shall flood the site to a depth of 50mm for 10 days. (Not
required on hydraulic fill sites). This requirement is because silty sands will
generally compact to a denser condition on first time flooding.
Sec 10: Building & Civil Engineering Works
10/11
On all fill sites the Contractor shall pipe rainwater from down pipes down to
paddy level and shall prevent water ponding in open foundations and backfill all
foundations as soon as possible.
The Contractor shall monitor settlement of the fill (by placing concrete posts 50 x
50 x 750mm deep on a 10 metre grid and taking readings) at 30 day intervals
from the time he is given access to each fill site.
When a fill site is handed over to the Contractor, the Contractor shall become
responsible for maintaining the entirety of the fill in good condition, including all
better slopes.
(b) Unfilled Sites
Original delta levels are generally below road level. Therefore most sites are
historically fill sites but fill settlement can sensibly be considered complete,
where fill is over 3 years old.
(c) Site Investigation
Detailed methodology for subsoil investigation shall be submitted before
implementing the subsoil investigation. All laboratory tests shall be done at the
test facility approved by the Employer.
The Contractor may appoint a sub contractor to carry out the site investigation
but all work and all lab work shall be witnessed by one of his own staff who
shall countersign all recorded data.
Boreholes shall be taken on a 25 metre grid with at least four additional boreholes
beside each building. Additional boreholes may also be required where uneven
fill depth is encountered. The number and location of boreholes shall be approved
with the site survey drawing showing existing ground levels specified in the
section 12.1.4. The boreholes shall be located to an accuracy of + 0.5m and shall
be located to site layout considering existing obstacles at the field.
Boreholes shall be a minimum of 20 metres depth or twice building footing
width, whichever is greater. All boreholes shall be backfilled with compacted
sand.
Borehole log together with a summary of all required laboratory tests is required
to be prepared. Soil test locations are required to be indicated on the geographical
map.
In each borehole the following tests shall be carried out:
-
Standard Penetration tests at 1.0 metre intervals.
-
Undisturbed samples shall be taken at around 2.0 metres depth and 3.0
metres depth
and tested by unconfined compression tests.
Sec 10: Building & Civil Engineering Works
10/12
-
One dimensional consolidation tests shall also be carried out on
undisturbedsamples taken at 2 metres depth. The samples shall be
saturated and the range of applied pressure shall fully reflect the insitu
conditions. Graphs showing void ratio (e) and applied pressure shall be
submitted along with the Coefficient of Compressibility for the range of
loading anticipated. Mv shall be in m2/MN and shall be recorded at each
stress increment. The coefficient of consolidation, cv, shall be given in
m2/year.
-
Particle size analysis shall be carried out for each stratum and specific
gravity, moisture content, liquid limit and plastic limit determined.
-
Ground water level shall be determined by dipping the boreholes. Where
collapse of the boreholes occurs, casing shall be used and left in until the
water level remains constant for two days.
-
In cohesive soils a vane test to BS 1377: Part 9 shall be carried out at three
different depths. The Contractor shall check the sensitivity of soil and
ground water at each site to concrete and take all measures necessary to
ensure the long term durability of concrete.
The Contractor shall give the Engineer the requisite period of notice prior to
commencing the geotechnical investigation at the field.
(d) Site Investigation Report
The site investigation and analysis of the data in a final report giving full details
of foundation proposals shall be completed at each site by the programmed date.
During site investigation, Geographical map shall be prepared indicating the
locations of soil test.
The report shall be submitted by the key date at each site given in the
programme. The Contractor shall submit 3 copies of the report to the Engineer.
The report shall propose full details of foundations and loading thereon and shall
provide estimates of likely settlements and differential settlements. The report
shall be the work of the Contractor's own foundation engineers.
If the Contractor uses a local site investigation contractor, he shall appoint one of
his own staff to oversee the entire operation and each piece of data shall be
countersigned by this person.
Where estimated settlement exceeds 25mm, the Contractor shall construct one
foundation at an early stage an test load this foundation to confirm settlement
predictions.
(e) Foundations
Regardless of the result of soil investigation report, the foundations of control
building, transformer foundations, gantry structures for terminating lines and for
Sec 10: Building & Civil Engineering Works
10/13
auto-transformers shall be provided with piles.
The minimum depth of all foundations shall be:
(a) Transformer bases and bund
1.0 m
(b) All other switchyard foundations
1.1 m
(c) Control building foundations,
1.5 m
including all wall
foundations
and internal wall
foundations
(d) Boundary wall foundations
1.1 m
All formations shall be hand rammed or mechanically compacted before placing
70mm minimum thickness of Class B concrete blinding, within 24 hours of
bottoming excavation, which blinding shall project 300mm minimum distance
beyond all footings. Each footing shall be inspected by the Engineer. Where soil
condition is poor (on fill sites or already filled sites) or where the Contractor
leaves foundations exposed and soil conditions deteriorate, one of the following
measures shall be carried out as agreed with the Engineer:
i)
Blinding depth and projection shall be increased
ii) Soft soil shall be removed and replaced with compacted viti sand with the
top 200mm consisting of viti sand and brick chips.
The cost of this work shall be borne by the Contractor.
The Contractor shall propose the allowable bearing pressure for all foundations
based on soil strength parameters only and shall not be increased while wind
loads exceeds 25% of dead load as well as shall not exceed 125kN/m2 . Between
column footings all walls, including all internal walls, shall be provided with a
reinforced concrete strip footing of minimum dimension 800mm wide by 250mm
deep placed at the same level as column footings and linked structurally to the
footings. In addition column footings shall be tied at foundation level and also
floor level by beams to every adjacent column in both orthogonal directions.
These beams shall be designed to resist 1 in 200 differential settlement without
distress and shall be capable of resisting the earthquake load of 0.2G.
The deepest parts of any foundations shall be completed first. All foundations
shall be completed and backfilled, including all cable tunnel and cable trench
work inside buildings, before walls are raised above floor levels. All other
foundations shall be backfilled within 7 days of completing concreting.
All exposed concrete and the outer surfaces of cable trenches and cable tunnels
shall receive two coats of bitumastic paint before backfilling to reduce ingress
of water. The Concrete surface shall be ground smooth and all air holes etc
Sec 10: Building & Civil Engineering Works
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filled (rubbed down with a cement slurry) before painting.
The Contractor shall monitor settlement of all foundations each month and
report this settlement to the Engineer until settlement has reduced to less than
1.5mm in 3 months.
The tops of all foundations shall terminate 200mm. above site average finished
surface level for new Substation & for existing substation the level should be as
per existing. All exposed edges shall have 20 mm x 20 mm. chamfers.
Excavation shall only be carried out when the ground water table is at least
1000mm below foundation level. The excavation shall be kept dry during the
construction period by providing sumps and pumps as required. During the
rainyseason, shelters shall be erected over all open excavations.
Any over excavation shall be filled with Class B concrete.
All backfill shall be compacted to 95% maximum dry density as defined by BS
1377 test method part 4, 2.5 kg rammer.
Before starting foundation work the Contractor shall clear all sites of trees, tree
roots, shrubs, debris, surplus soil, and any buildings.
Foundations shall be designed to resist uplift, assuming the water table is at
ground level and the weight of soil resting on a foundation is that included within
a 15˚ frustum.
On fill sites where the depth of fill exceeds 3 metres, the Contractor shall provide
piled foundations in accordance with BS 8004 for control buildings.The design of
foundations for transformer, gantry, equipment support structure, etc shall be as
per requirement of subsoil investigation report. One working pile of each
structure chosen by the Engineer shall be load tested at each site to 150% of
design load in accordance with BS 8004.
10.3.3 Drainage
The entire surface within boundary walls shall be of uniform sloping site, sloping at 1
in 150 minimum slope to open channels around the entire perimeter. These channels
shall be designed for a rainfall intensity of 60mm per hour. Outside the boundary wall
the Contractor shall be responsible for drainage up to 20 metres from the wall and
will at some sites need to construct outlets with suitable erosion protection down to
paddy level.
The concrete wall of cable trenches shall project at least 70mm. above brick paving
level to prevent run off entering the cable trench. The floors of all cable
trenches/tunnels shall be sloped to soakway as described in 12.3.16.
The cable trenches will thus form barriers to surface water drainage. If the cutoff area
exceeds 30m2 it shall be drained by a 200mm minimum diameter concrete pipe to the
boundary drain. The Contractor's drainage design shall avoid all ponded water to
avoid forming a mosquito breeding ground.
Sec 10: Building & Civil Engineering Works
10/15
All drainage pipework within buildings shall be ductile iron, generally of 100mm
diameter. Floor drains shall be placed in each battery room and toilet.
External pipework shall be 150mm. minimum diameter concrete pipes at a minimum
depth of invert of 700mm. Where pipes, including existing pipes alongside site, are
less than 400mm above adjacent foundations they shall be surrounded in concrete.
Where required, drainage pipes shall be kept below cables, allowing 1.1 m cover to
top of pipes.
Manholes shall be of brick construction with 600mm. x 600mm clear openings and
airtight ductile iron covers to BS EN 124. Manholes shall be located at each change of
direction. Minimum fall on all pipelines shall be 1 in 80. Manholes shall not be
located in roads.
The Contractor shall be responsible for all negotiations with local authority WASA
where a connection to a public sewer is proposed. Where high water levels in public
sewers may cause effluent to back up into a site, non return valves shall be fitted. The
Contractor shall provide all protection required to existing sewers and shall deepen
foundations, including boundary wall foundations, where required to ensure all
foundations are below adjacent sewers. The Contractor shall draw longitudinal
sections of all pipelines.
Main control building shall be provided with a septic tank designed for 10 users and a
soakaway of open brick construction 11m deep by 2.2m diameter filled with broken
bricks. The septic tank shall be located at least 15 metres from buildings. Other
buildings shall have septic tanks designed for the required number of users. All foul
drains shall be vented by a vent pipe to above roof level. The inner surface of all
manholes and septic tanks shall be painted with 2 coats of bitumastic paint to protect
it against sulphate attack. The septic tank shall have access holes directly over the
inlet pipes and outlet pipes. Where public sewers exist alongside a site, the Contractor
shall connect directly to the foul sewer, provided effluent from the sewer is treated.
The Contractor shall construct the drainage first to ensure that at no stage is rainwater
ponded on any part of the site. All rainwater shall be able to run off the site or shall be
immediately pumped off site by the Contractor. The Contractor shall complete all
necessary drains before casting any roof and large concrete area which will create
large run off. The condensate drains for the air conditioning shall also be connected to
the drainage. Two vents of minimum height 2.2m shall be provided on each septic
tank.
If a town's water supply is unreliable, the roof rain water shall be collected in an
underground tank of standard Employer's design.
10.3.4 Surfacing
For the whole of the switchyard outdoor equipment area the ground shall be surfaced
with gravel or other readily available local stone as approved by the Engineer. The
Sec 10: Building & Civil Engineering Works
10/16
switchyard surfacing shall be clean, thoroughly washed when necessary, and free
from clay, soil or contaminating material and shall be graded from 20 - 45mm, laid
and lightly compacted to a finished thickness of 175mm. Below the gravel layer there
shall be a 75mm brick layer with cement mortar (1:6), laid over a 75mm level of fine
sand spread over the finished fill site.
The substation plot, outside of the designated switchgear equipment areas, shall be
turfed. Turf shall be of good quality, free from weeds and shall be a minimum of
40mm thick. Samples of the turf which is proposed to use shall be submitted to the
Engineer for his approval. The turfs shall be laid to even surfaces on a bed of
vegetable soil, which shall be raked and consolidated to provide a suitable bed.
On sloping surfaces the Contractor shall provide and fix wooden pegs to retain turfs.
All areas to be surfaced shall first be treated with a total weed killer in accordance
with the manufacturer's instructions. Weed killer shall only be applied in dry weather
when there is no risk of it being washed out to adjacent agricultural areas.
10.3.5 Roads
Access road from outside the site boundary to connect to any adjacent public road and
all roads within the site boundary shall be provided by the Contractor.The access road
(the road connecting nearby main public road to substation main entrance gate) length
assumed to be 10meter, if more than 10 meter length is required then Employer will
pay the extra cost as per contract rate schedule. The road surface shall be finished by
concrete paving or equivalent.All roads shall be of reinforced slabs of approximately
25 cm thickness fitted with construction joints.Paving schedule and methodology
shall be approved by the Employer. The extent of roads required is shown
approximately on Bid drawings but the scope of the work may change. Road layout
shall generally permit vehicles to turn easily to avoid having to reverse out. Road
layout shall be designed by the Contractor. The Contractor's Liability for roads
outside the site shall be as stated in the Project Requirements of Volume 1.
The width of access road from outside the site boundary to connect to any adjacent
public road shall be 6 meters. All roads within the site boundary shall be generally
6metres wide between the outer edges of kerbs for main road and 4.5meters wide for
sub road.
The road edge shall be formed by a flush Class B concrete kerb 300mm wide by
250mm deep, placed over one layer of bricks laid flat. The road shall be a Class A
concrete slab 150mm deep with 1:50 cross fall and stiff broom concrete
finishreinforced with 6mm bars at 125mm centres longitudinally and 6mm bars at
400mm centres transversely placed 60mm below the upper surface. Expansion and
contraction joins shall be detailed on site plans. Expansion joints shall have an oil
resisting grade polysulphide sealant. Below the slab shall be a layer of polythene
0.5mm thick laid over one layer of 1st class bricks laid on edge in herringbone
fashion in and on cement mortar (mortar designation iv) laid over one layer of 1st
Sec 10: Building & Civil Engineering Works
10/17
class bricks laid flat in and on a layer of sand laid on insitu soil which shall be
compacted as agreed with the Engineer. If the soil is clay a 75mm drainage layer of
broken bricks shall additionally be placed over the soil.
The radius of the road edge at corners shall not be less than 3 metres and 1.2 metres
either side of the road shall be kept clear of obstacles. Bollards or raised kerbs shall
be provided where required to protect items alongside a road from vehicles. Ducts
shall be provided below roads for all services in this Contract and for all future
services.
Where mortar designations are referred to see BS 5628 Mortar designation iv is 1
cement: 2 Lime: 8 to 9 sand.
At each new substation site a two bay hard standing car port, complete with sun
shades, is to be provided adjacent to the control building.
10.3.6 Water Supply
The Contractor shall be responsible for providing a water supply both for construction
and for operation of the completed sites. If a town's water supply is not available, the
Contractor shall install a tubewell of 40mm minimum diameter and 100m minimum
depth but in that case guideline specified by WHO for drinking water is required to be
satisfied. The Contractor shall supply and commission power supplies and all pumps
required by tubewells.
If a town's water supply is available, the Contractor shall be responsible for making
all necessary arrangements with WASA to connect a supply. If the pressure in the
supply is inadequate to supply the roof tank continuously, the Contractor shall install
a 1800 litre low level tank and pumps. This tank shall be below ground with a 200mm
minimum air void around the tank to protect it from contamination. The pump control
panel shall be located in the building. Water levels shall be controlled by float
switches but the panel shall provide also for manual operation.
The supply shall be connected to a 1800 litre roof tank of 16 gauge galvanised steel
plate with a lid secured by bolts. The tank shall be raised 400mm clear of the line
terracing on four brick piers of minimum 350mm square. All supplies in buildings
shall be fed from the roof tank. The supply to the tank shall have a valve at waist
height. The tank shall have an overflow returning to the location of this valve. No
pipes shall pass through the roof directly over any room. Pipework shall be routed up
the outside of the building and return pipes shall return down the outside of the
building before entering through the wall. Pipework shall be galvanised steel secured
by clamps at 1-5 metre intervals and painted with alkyd paint to match walls.
10.3.7 Plumbing and Sanitary Fittings
The Contractor shall prepare a drawing of all plumbing and building drainage for
each building. Sanitary fittings and plumbing materials shall generally be of approved
Sec 10: Building & Civil Engineering Works
10/18
local manufacture.
In main control building each toilet shall have a single oriental WC pan with P trap
with a high level cistern of 10 litres capacity. Each toilet outlet shall be vented by a
100mm diameter ductile iron vent pipe passing up the outside of the building to
300mm above roof level. Beside each toilet shall be placed a low level tap. Main
control Building toilets shall also have a wash basin and old and hot water shower.
Toilets and showers shall have all walls tiled to a minimum height of 2.5m.
Every tap and cistern shall have stop cocks in the supply pipe. One external tap shall
be provided on each building. Battery rooms shall be provided with a stainless steel
sink of approximate dimensions 900 x 600 x 200mm with a draining board to one
side. The battery room floor drain shall be connected to the foul drainage. All floor
drains shall have P traps.
Mirrors shall be installed over toilet wash basins. Care shall be taken in orientation of
toilets to avoid offending religious sensitivities. Toilets shall generally be orientated
North South where possible. Each shower shall have a wall on two sides and a
porcelain shower tray sunk into the floor. Soap dishes shall be provided beside each
shower.
Only foul water from WC pans shall be connected to septic tanks. All other water
shall flow to surface water drains.
10.3.8 Building Floors
All topsoil containing roots shall be removed and the insitu soil compacted before
placing backfill. All backfill, including the backfill to column footings, below the
floor shall be sand but around the perimeter walls a band of broken brick 600mm
wide shall be placed with drain holes placed in the walls at 2.5 metre centres. The
floor and all cable trenches shall be made of Class A concrete. The floor slab shall
have a minimum 125mm reinforced concrete Class A thickness, plus 25mm Terrazzo
and it shall rest on the fill. Below the slab shall be placed a layer of polythene 0.5mm
and a layer of compacted broken bricks at least 75mm deep, hand rammed to a
smooth upper surface.
The floor/equipment layout shall minimise the number of cable trenches over which
station staff have to walk. Where power cables traverse a building to reach a
switchgear room on the far side they shall generally be contained within a dedicated
cable basement or cable tunnel.
All sand backfill shall be compacted to 90% optimum density and shall be tested. The
fill within a building, above ground level, shall not be placed until all backfill outside
the building is completed. All floor slabs shall have a damp proof membrane of
0.5mm thickness.
Each control building shall have a ramp at a slope of approximately 1 in 7.5, of 1.5m
minimum width with a Concrete Class A slab of min depth 125mm with a stiff brush
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concrete surface finish, or other agreed non slip surface.
All floors except battery rooms shall have homogeneous floor tiles. Verandahs and
external steps shall also have homogeneous floor tiles where public access is given to
buildings. Elsewhere, concrete surfaces shall be used for all external floors/steps.
Verandahs shall have a minimum 1: 50 slope to shed rainwater away from buildings.
Maximum length or breadth of any panel shall be less than 1.75 metres. . 200mm high
skirting shall be installed beside each wall. Concrete floors and steps shall also be
treated with 3 coats of Lithurin or other approved concrete dust proofer.
If floor tiles are not adequately durable to withstand switchgear movement when
rolled out to the maintenance position, then galvanized steel chequered plates shall be
inserted in the floor to resist the abrasion from switchgear wheels.
10.3.9 Cable Basement
Below ground level basements to buildings shall be of waterproof construction;
designed and constructed in reinforced concrete to BS 8007 and BS 8102 [Type C
(Drained protection) ]. The external walls and base slab shall be a minimum 350mm
thick. The design shall assume that the ground water table is at ground water level.
The walls and floor of the basement shall have a drained cavity with ventilation
provided. The cavity shall drain to a sump, equipped with one hand operated and one
electric pump, to facilitate the removal of water. The electric pump shall be of the
submersible type with automatic control by float switches. The hand driven pump
shall be rotary action and valveless giving smooth non-pulsating flow.
The basement shall be provided with air extraction equipment, 100% standby
equipment to give uninterrupted ventilation, sufficient to change the air 6 times per
hour. Air supply and exhaust shall be from within the building at ground floor level in
a protected location and shall not connect directly to the outside. The stairs leading to
the basement shall be enclosed with, from ground level and at basement floor level,
entry through security doorsets. Sufficient air ducting shall be provided to ensure
adequate ventilation to the basement even if the extract fans cease to operate.
The basement shall be equipped with lighting and small power.
Where cables enter the building all ducts and trenches shall be sealed; the ends of all
ducts entering trenches shall be bell-mouthed. The floor shall be screeded, the walls
finished as per the schedule of finishes.
10.3.10
Battery Room Floors
Battery rooms shall have a concrete floor sloping to a cast iron floor drain. The
concrete surface shall be treated with Nitocote epoxy resin coating (Nitoflor primer
plus two coats of Nitocote in accordance with manufacturer's instructions), or similar
approved material, to ensure resistance to battery electrolyte. There shall be no cable
trenches in battery rooms. Cable entrances through the floor shall be protected by a
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raised plinth 50mm high around the opening with the annulus around the cable sealed
after installation.
10.3.11
Control Room Floors
Control rooms where specified in the bid drawings shall have a raised floor (Multi
access floor). The contractor shall submit the drawings showing required details for
construction of raised floor for approval by the Employer’s representatives.
The raised floor shall be made of poly-urethane material having functions of fire
resistance, waterproof and soundproof. Each panel of raised floor shall be installed on
the structure frame. The floor material shall have function to easily accommodate
cables, communication wiring, etc. on its lower part. The floor material shall include
the shock-absorbing material and finishing stuff.
Panel elements shall be produced without fading or peeling on the finishing stuffs and
trim by the injection molding of finishing stuff with panel elements at the same time.
By the injection molding, the panel’s thickness and the other standard (width, length,
thickness, opposite angle, right angle, flatness angle, etc.) should be precise.
Pedestal elements shall have the function of support for the panel element of raised
floor material.
Shock-absorbing material shall be installed on the top of pedestal elements and
prevent any vibration or impact of the panel elements.
The materials for raised floor shall be as shown below or similar. The details should
be approved by the Employer.
- Panel stuff: poly-urethane
- Panel dimension: 600 x 600 ± 0.5mm (including finishing stuff, trim)
- Panel thickness: 40 ± 0.5mm (including finishing stuff)
- Panel inside core: particle board 35mm
- Panel frame: width 3mm poly-urethane
- Finishing stuff: anti-static laminate tile
- Under structure: zinc electric galvanizing
- Central concentrated load transformation: less than 2.5 mm with 4,900 N
The materials should be kept on the well-ventilated places against rain and direct ray
of light. When transporting and handling the stuffs, the handler should be alert not to
be damaged. The damaged materials have to be taken out. The finishes of stuff have
to be stuck in the panel element.
The floor surface must be dry before construction, also the impurities like dirt and
other obstruction should be removed. The under-structures (Pedestal set) are installed
at intervals of 600㎜ from the starting point of construction like radial shape. At this
time, the under-structure is fixed strongly on the floor surface by using an adhesive.
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When each supporting structure is connected to the frame (stringer), the leveling work
shall be done together. Horizontal angle shall be checked again after the construction
is finished.
Panel lifter and other accessories necessary for maintenance shall be provided by the
Contractor.
10.3.12
Site Clearance, Obstructions and Adjacent Structures
The Contractor shall be responsible for clearance of:
(1) Trees, shrubs and any vegetation including the extraction of all roots and
compaction of backfill where roots have been extracted.
(2) The removal of all buildings, sheds or any other structures above or below ground
including the removal of any septic tanks, drains or other underground services.
(3) The removal of any existing surfacing, roads, foundations or any other
obstruction.
All material cleared away by the Contractor shall be the property of the Employer and
shall be removed by the Contractor to a site in the Project area upon instructions of
the Employer. The Employer may remove any buildings or structures himself from
sites before the commencement of site works.
Where an existing service, existing equipment or adjacent building is to be retained,
the Contractor shall take all necessary measures to protect the item concerned from
damage and shall be responsible for ensuring that no movement of foundations occurs
during or after completion of construction.
Any existing services (electrical/gas/water) dedicated for employer’s own use which
have to be modified or repositioned shall be included in the works at no extra cost.
However, where it is possible to retain these existing services and build new
structures around them, the Contractor shall take all necessary measures to build in
the service at no extra cost. Any electrical equipment /cables (except 11kV or higher
voltage overhead/underground live lines) which have to be modified or repositioned
shall also be included in the works at no extra cost. Any buried gas or water main
services or electric overhead/underground live line (11kV or higher voltage) which
require to be diverted shall be diverted by the Employer at his cost.
10.3.13
Guard Houses, Boundary Walls, Fences and Entrance Gates
The guard house serves for control of entrance. The gatekeeper shall be able to watch
the area before and behind the guard house. The guard house shall be provided with
water supply and toilet.Small power and lighting facilitates are to be provided in the
Guard Houses.
Where sites are within existing Employer's boundary walls, the Contractor shall erect
a permanent fence 2.9m high in accordance with BS 1722 part 10 or similar approved.
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10.3.14
Windows
Even natural light shall be provided by windows to illuminate all areas of buildings.
Window area shall be about 6% of floor area to limit solar heat gain. Tops of
windows shall generally be below 2.5 metres from floor level but toilet windows may
be higher. The bottom of windows shall be generally at least 1.45 metres above floor
level to provide good protection to staff. Each window shall be provided with a
sunshade projecting about 500mm from the wall above and at the upper sides of the
window. Few windows shall be placed on south facing walls. Windows shall be
spaced to give a wide view of the switchyard.
Windows shall have single glazing with 6mm thick glass, reinforced with wire mesh
where windows are placed in or over doors.
Window frames shall be anodised aluminium.
Glass panels shall be placed over doors to provide natural light to internal corridors
and rooms where required.
External cills shall have a sloping tile or similar detail with drip.
The Contractor shall prepare a window schedule for each building.
The schedule shall clearly indicate both fixed and opening windows.
The Control and Switchgear rooms in particular shall have opening windows to allow
adequate ventilation.
Guard Houses are to include for opening windows with burglar bars and shutters.
Small power and lighting facilitates are to be provided in the Guard Houses.
10.3.15
Doors
Internal doors and door frames shall be anodised aluminium. Main Entrance/Exit
doors and door frames shall be steel.
The minimum size of the structural openings for doors shall be 1550mm. wide for
double doors and 930mm wide for single doors. Door height shall generally be
2100mm but switchgear and control rooms shall have a removable transom and
removable panel over the door or a taller door to provide a total height of about
2500mm. All door sizes and widths shall be adequate to get in and get out all
equipment and future equipment.
All external doors shall have weather boards, hydraulic closers and cabin hooks to
hold the door open. External doors shall open inwards, except for switchgear room
doors which must open outwards and be fitted with panic release latches.
Each door leaf shall have three 150mm heavy iron hinges equally spaced. Door
furniture shall be of approved local manufacture and shall generally be of brass. All
corridor doors, external doors and rest room (toilet) doors shall be fitted with
hydraulic closers. Door stops shall be fitted where required. Door frames shall
Sec 10: Building & Civil Engineering Works
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generally be set 200mm off a wall junction to enable the door to open fully through
90˚.
All external doors shall be shaded by either the roof canopy or a separate precast
concrete canopy over the top and the upper sides of a door.
The Contractor shall prepare a schedule of all doors and all door furniture for each
building.
10.3.16
Brickwork
Brickwork shall be designed to BS 5628. External panels of brickwork shall be
checked for wind pressure calculated in accordance with BS 6399 for a wind speed of
160 kph 3 second gust.
Bricks shall be first class bricks from approved manufacturers. 10 bricks shall be
tested in accordance with BS 3921 to determine water absorption and crushing
strength, which shall exceed 20N/mm2. Mortar shall generally be of Mortar
designation (iii), 1: 1: 5 to 6. cement, lime, sand.
All brick panels shall be tied to the concrete frame with galvanised ties of approved
design. Ties shall be painted with bituminous paint.
Facing bricks shall be 8" x 2" x 2" facing bricks from Mirpur ceramics. Facing bricks
shall be tied back to the main wall. External walls shall be 230mm thick brickwork,
rendered internally and clad externally with facing bricks or rendered as required by
the architectural plan.
Bricks shall be compacted down onto a full bed of mortar. Vertical joints shall be
completely filled with mortar. Joints shall be raked out about 10mm deep where walls
are to be rendered.
Brick walls shall be constructed so that tops of all meeting walls are about the same
level with maximum variation of 0.75m. Only 18 courses per day shall be laid. New
work shall be protected from sunlight and drying winds for 4 days.
Lime and cement for all brickwork shall be stored in a dry building with a raised dry
floor.
Reinforcement by mild steel rods shall be provided where required by the design.
Additionally openings over 500mm. wide shall be reinforced for 2 courses above and
below the opening, two 6mm. bars per course extending 900mm beyond the opening
both sides where possible.
All exposed brickwork shall be rendered and painted where not faced with facing
bricks.
10.3.17
Expansion Joints, Joint Fillers and Sealants
Expansion joints shall be placed in floors beside all ground floor walls. All filler
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board shall be bitumen bound fibre board. Any expansion joints on roofs shall be
raised and protected by a metal flashing.
All expansion joints shall be sealed by polysulphide sealants, applied in accordance
with the manufacturer's instructions. Sealants shall be oil resisting grade where
required. Sealant colours shall match or blend with adjacent wall colours.
10.3.18
Cable Trenches in Switchyards
Cable trench sizes shall be standardised. Layout drawings shall be submitted for each
substation showing layout and size of trenches. No trench shall cross a road; power
cables shall be placed in ducts of minimum 150mm diameter with bell-mouthed ends.
Ducts shall extend 1500mm minimum beyond the edge of roads. Spare ducts shall be
installed for likely future development.
Floors and walls of trenches shall be constructed of Class A reinforced concrete of
minimum 150mm thickness, with the external surface painted with two coats of
bitumastic paint. Walls and covers shall protrude at least 70mm above site finish level
and the top of the wall shall be flat with no rebate. Floors shall be sloped at 1: 150
minimum slope to brick soakaways placed below the trench at low points; the volume
of each soakaway shall be 2.5m3 per 150m2 of trench.
Covers shall be of reinforced concrete Class A. Each cover weigh less than 55 kg.
The minimum depth shall be 70mm, with downstand ribs along each side providing a
minimum overall depth of 100mm. The ends of the cover shall overhang the wall by
15mm and in the centre of each end there shall be a hand hole of minimum size
100mm by 20mm high. This hole shall allow air to ventilate the trench so that heat
built up in the trench shall be reduced. No gaps larger than 5mm shall be left between
adjacent covers so that the cables are always shaded. Cover slabs shall sit squarely
and uniformly on the trench walls without the need for bedding or shims. Because
portable fire extinguishers will be rolled over and along trenches, each cover shall be
capable of resisting a 250kg point load at mid span. The Contractor shall provide
ramps up to the edge of covers in several locations, as agreed on site, to enable the
wheeled extinguisher to mount the covers. Longitudinal edges may be inclined at 10˚
to the vertical, thus creating a larger gap at the bottom of adjacent slabs, again to
reduce heat buildup. The upper surface of covers shall have a stiff broom non slip
concrete finish. All sharp edges shall be stoned smooth. Outer edges shall be
chamfered.
Longitudinal fire separation walls and transverse fire separation walls as required by
the cable section, may be of brick or reinforced concrete.
10.3.19
Cable Trenches in Buildings
The base and walls of the trench shall be of reinforced Class A concrete of minimum
thickness 110mm with the outside face painted with 2 coats of bitumastic paint. Cable
trays may be supported by Unistrut P3300 inserts, or similar approved, or drilled
Sec 10: Building & Civil Engineering Works
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anchor bolts.
The building layout shall minimise trench lengths. Where power cables pass through
a building to reach the far side, this shall generally be in a tunnel section. The
Contractor shall be responsible for providing all trenches and ducts in a building,
including ducts for outgoing power cables up to the site boundary and including any
pulling pits required.
Trench covers shall be sheets of composite board, PERMALI YA 729 or similar
approved, consisting of wood fibres impregnated and compacted in synthetic resin, or
a computer flooring composite board. The weight of each cover shall be restricted to
about 30 kg. The upper surface shall be non slip. Deflection shall be limited to 1/250
of span under a load of 3kN/m2. Only one thickness of board shall be used to
standardize the edge support detail. The recess to receive the cover shall be protected
by steel or brass on the vertical edge and bedding surface. Covers shall fit snugly
around all cables. Where cables enter the building, all ducts/trenches shall be sealed.
Fire/oil barriers shall be required to separate hazardous equipment. The ends of all
ducts entering trenches shall be bell-mouthed.
Any beams used to support large span covers shall be removable. All metal work
shall be painted as specified in the paint section.
All covers shall bed down evenly. Full detailed fabrication drawings shall be provided
for all covers.
10.3.20
Rainwater Pipes
Down pipes shall be 100mm minimum diameter placed on the outside of walls but
enclosed in a brick buttress of facing bricks. One downpipe shall be provided for each
100m2 of roof area. The head of the downpipe shall be enlarged to 200mm diameter
and a purpose made cast iron grill provided over the head. This grill shall be sited in a
recess in the roof slab projection.
The foot of the pipe shall have a 90˚ bend and water shall be discharged into either:
i)
a small open channel conveying the water to the boundary channel
ii) a pipeline conveying the water off the site. Rainwater shall not be
connected to the septic tank or allowed to discharge directly onto
switchyard paving.
10.3.21
Switchyard Foundations
The tops of all foundations shall be set at the same level, which shall be raised above
the general switchyard level for the purpose of preventing surface water coming into
contact with the equipment structures and holding-down bolts. The distance between
the general surface level and the top of foundations shall be at least 200mm. All
exposed concrete surfaces shall be painted with an acrylic weatherproofer or
bituminous paint, and flat areas shall be sloped to shed water. No base shall permit
Sec 10: Building & Civil Engineering Works
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ponding of water in any way, and free drainage shall also be possible from all areas
inside any grouting.
Bases shall generally be of Class A reinforced concrete.
Bases shall have all recesses for cables and earthing detailed on drawings. The
drawings shall clearly show the orientation of each base and the location of all
recesses. Where new foundations are adjacent to existing foundations; the Contractor
shall be responsible for verifying the extent of the existing foundation and ensuring its
stability.
For anchorage design of switchyard foundations shear force, vertical accelerations,
overturning moments and torsion due to mass eccentricities of the equipment for the
earthquake load of 0.2G are required to be considered. Mild steel ductile bolts and
headed studs cast-in-place anchor bolts shall be used. Thick plate washer is required
to be welded to the equipment base plate. Normal washer shall be used under a nut in
all cases.
10.3.22
Transformer Bases
The transformer base, together with its surrounding bund shall form a raft to distribute
the load from the transformer over the entire area within the bund wall. The bund
shall extend at least 700mm beyond any part of the transformer and its radiators. The
level of the top of the bund and the skids shall be 200mm above general switchyard
level. Skids shall extend to the edge of the bund. Where separate transformer cooler
banks are provided, the cooler banks shall also be protected by the bund.
50mm below the top of the wall shall be placed a layer of stone 225mm deep set on a
galvanised grill painted with two coats of bitumastic paint. The volume of the bund
below the stone shall equal 125% of the total volume of oil in the transformer and its
radiators.
Rainwater will tend to collect in the bund. To evacuate rainwater a fixed submersible
pump controlled by sensors and switches (Aqua Sentry or equal) shall be provided at
each bund with power supplies and drainage manhole conveniently located. The bund
water control system shall differentiate between water and oil to ensure that the pump
will not be activated while oil is present in the bund.
The transformer base and the bund shall be founded a minimum 1.0 metres below
average switchyard finished level.
Below the skids the walls shall be at least 600mm wide. Piers shall be provided below
the jacking points. Each base shall be provided with two galvanised steel removable
pulling posts on the other side of the access road to the bund and also at the back of
the transformer bund.
The entire concrete surface of the bund and the transformer base which is not buried
shall receive two coats of bitumastic paint. Skids shall receive 3 coats of bitumastic
Sec 10: Building & Civil Engineering Works
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paint before being cast in.
A carriage way shall be provided with rail connected with all transformer bases.
Transformers shall be anchored to resist the earthquake load of 0.2G.
10.3.23
Blast Walls
The Contractor shall construct blast walls to reduce the risk of fire spreading from
each three phase transformer unit to an adjacent transformer unit or control building.
Blast walls shall also be constructed to resist impact forces causing from a
transformer explosion damaging adjacent equipment.
The width of the blast walls for transformers shall be 500mm higher than the tops of
transformer or same height of the tops of the HV bushing and 300mm wider at both
sides than the width of transformer. The thickness of blast walls shall be 200mm.
The wall may be constructed in brickwork or reinforced brickwork rendered and
painted as the control building or Class A reinforced concrete with all exposed edges
chamfered, and the whole wall rendered and painted as the control building.
10.3.24
Paints and Painting
All paints shall be of approved makes and colours and proven suitability for the
prevailing climate and shall be approved by the Engineer. All surfaces for painting
shall be cleaned down prior to being painted and rubbed down to a smooth finish.
All externally exposed concrete and render of the control buildings, boundary walls,
blastwalls and guard posts shall be painted with a fungicide, Snowcem primer and
two coats of Snowcem. All exposed facing bricks and Snowcern painted surfaces
shall be treated with one coat of clear silicone (5%) water proofing solution.
All exposed parts of foundations, the outer faces of cable trenches and cable tunnels
shall be painted with two coats of bitumastic paint.
All ungalvanized metalwork shall receive two coats of red oxide paint at least 4 days
before installation and shall receive two finishing coats of paint after installation, each
coat being of different colour. Surface preparation before painting shall be SA 2.5 or
an agreed rust convertor acid shall be used. All galvanized steel, including all brick
ties, boundary wall wire supports, cranebeams, baseplates and holding down bolts and
concrete plinths shall receive two coats of bitumastic paint. Galvanized steel shall not
be painted until the surface has weathered.
Internal walls when fully dry shall have the surface rubbed down with sandpaper and
be painted with a sealer and 2 finishing coats of plastic emulsion paint before
equipment is installed. A further finishing coat shall be applied after completion of
installation.
One day shall be allowed for drying of each coat before the next coat is applied.
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The interior of all septic tanks and manholes carrying foul sewage shall receive two
coats of bitumastic paint.
10.3.25
Furniture
The Contractor shall supply a complete set of tables, chairs, stools, desks, benches,
storage shelves and drawing cabinets as described in the Project Requirements,
Volume I with layout top, for drawing examination, lockable cabinets for spares and
test equipment and key boxes in each control building. These shall generally be of
steel of local manufacture and shall be of robust durable construction. In each rest
room (toilet) two couches, approximately 900mm wide by 1900mm long with back
rests against the wall, shall be provided.
The full details and specification of these materials shall be agreed before purchase.
The Contractor shall arrange for a list of items to be handed over to the Employer,
who will sign for receipt of a complete set as stated on the list.
10.3.26
Concrete
Only two grades of concrete shall be used. Class A shall be used for all structural
work, piling and for all foundations which are not unreinforced massive blocks. Class
B concrete shall be used for blinding, pipe surround and unreinforced or nominally
reinforced concrete. Road slabs and floor slabs shall all be reinforced Class A
concrete.
Class A
MinCement Content
Max Water Cement ratio
Coarse Aggregate type
Max Coarse aggregate size
Method of Batching
Min Characteristic of Trial
Mix at 28 days
Min characteristic strength
of trial mix at 7 days
Min characteristic strength
of works cubes at 28 days
Slump Range
Slump for concrete placed
below water in piling
Class B
360kg/m3
170kg/m3
0.55
Broken stone
Jhama brick
20mm (40mm piling) 25mm
Volume batching
Volume batching
30N/mm2
14N/mm2
-
20N/mm2
30mm min-100mm max
-
50mm min
150mm min
It should be noted that minimum specified cement content will produce significantly
stronger concrete. The Contractor's design shall be based on a 28 day crushing
strength of 20N/mm2. Design shall be in accordance with this Contract and BS 8110
Sec 10: Building & Civil Engineering Works
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or other agreed standard.
Minimum cover to rebars shall be 60mm where concrete is in contact with backfilled
soil against a shuttered face, 100mm where concrete is cast against soil, and 30mm
for all above ground concrete. In detailing bars which traverse a member, a reduction
of 5mm shall be made for a bent bar and 10mm for a straight bar to ensure adequate
cover. Exposed ends of sunshades and roof projection shall have 70mm minimum
cover.
All concrete design shall ensure easy access for vibrators of 50mm. minimum
diameter. Because of the slowness of concreting using local methods of transport,
congested reinforcement details and shapes which are difficult to concrete should not
be used. The location of all cold joints shall be agreed in writing with the Engineer
and all joint surfaces shall be scabbled. All joints shall be horizontal or formed
against vertical stop ends. All cold joints shall be indicated on drawings. Roof slabs
shall generally be cast in one continuous operation.
10.3.27
Concrete Reinforcement
The Contractor may use locally available mild steel bars from approved sources or
import steel bars to any agreed standard. No bar or stirrup shall be smaller than 6mm
diameter to ensure adequate rigidity during concreting.
If locally purchased bars are used, bending tests and tensile tests shall be carried out
to ensure the bars meet the design standard adopted and weight per unit length shall
be tested regularly.
Bar bending lists shall generally be shown on drawings, where possible with a
diagrammatic representation of each bar to ensure clarity and ease site
communication. The Engineer will not systematically check the accuracy of every bar
on bar lists when approving drawings. The Contractor shall therefore arrange to check
all bar lists. Drawings shall detail all chairs and ties and include these on bar lists.
Bars shall be tied at every intersection and the ends of tie wire bent away from
concrete surfaces.
Anti crack bars shall be provided at changes in slab or wall thickness and at the
corners of every rectangular opening.
10.3.28
External Render
All brickwork which is not faced with facing bricks shall be rendered. Concrete
columns and walls shall be rendered and painted in accordance with BS 5262 with a
3mm spatterdash coat a 12mm undercoat followed by a 9mm finishing coat. Surface
preparation shall be as described in BS 5262. Joints shall be provided in all render
where brickwork panels abut concrete columns and grade beams, as required by BS
5262.
A mix type II or III shall generally be used. The finishing coat shall be weaker than
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the undercoat.
The tops of all foundation blocks and all protruding concrete foundations shall also be
rendered where required by the Engineer.
PVA Bonding agents shall not be used because of the risk of early drying in the
tropics. All concrete surfaces to be rendered shall have the entire surface scabbled and
brushed with a stiff brush to remove all loose material. The surface of the undercoat
shall be roughened to ensure bonding of the finishing coat.
All render once completed shall be kept continuously damp for 10 days, after which if
shall be treated with a fungicide. Any existing backgrounds shall be treated with a
fungicide and all growth cleaned after 5 days of contact with the fungicide.
10.3.29
Goalposts
In each outdoor switchyard with live conductors crossing roads the Contractor shall
erect a permanent goalpost at the edge of the danger area with red and white metal
warning boards hanging down from the goalpost to warn high vehicles of the
overhead danger. This structure shall conform and match those supporting structures
in Section 11 of this Contract for the high voltage switchgear.
10.3.30
Lifting Beams
In two storey control buildings a galvanised steel lifting beam shall be provided for
hoisting equipment to all upper floors. The beam shall be fixed permanently in place
and shall project the required distance from the building to lift the largest equipment
from road transport. Beams shall be designed in accordance with BS 2853 and
deflection shall be limited to 1/900th of span. An approved (Morris of Loughborough
190 Series with Morris 164 travelling trolley or similar approved) hand chain hoist
with hand geared travel and travelling trolley of capacity to suit the heaviest
equipment or future equipment shall be provided on each beam. The chains shall
reach to lorry level and provision shall be made to hang up the chains to one side
when not in use.
Inward opening doors shall close around the beam and be shaped to a close fit.
10.3.31
Stairs
Except where indicated otherwise in the schedules, all single storey buildings shall
have an external staircase up to the roof; the minimum staircase clear width shall be
750mm and the maximum slope about 33˚, all detail being designed in accordance
with BS 5395. These staircases shall not be enclosed. The design shall allow free
circulation of air over the treads and through the risers. Non slip nosings shall be
provided.
Two storey buildings may either have an internal or external staircase, which shall
have a minimum clear width of 1 metre with a maximum slope of 30˚, all detailed in
Sec 10: Building & Civil Engineering Works
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accordance with BS 5395. External staircases shall not be enclosed but shall be
completely protected against rain by roof projections; steps shall be open with non
slip nosings. Internal staircases shall be terrazzo with non slip nosings. Solid rendered
and painted walls, at least lm high, shall be provided alongside each flight of stairs.
All roofs which are not accessible by stairs shall be provided with a galvanised steel
fixed ladder.
10.4
CONCRETE WORKMANSHIP
10.4.1 General
At all stages in the production, mixing, placing and curing of concrete, the work will
be inspected by the Engineer's representative. If any material, dimension or practice is
not at least equal to the standards set out herein, it shall be rejected and alternatives
compliant with the said standards, and in addition to the satisfaction of the Engineer,
shall be implemented.
10.4.2 Aggregates
Coarse aggregate shall be capable of passing through a 20mm sieve and be retained
on a 5mm sieve. Fine aggregate shall be not larger than 5mm and not smaller than
0.06mm and shall be sharp in texture.
All aggregates shall be free of harmful quantities of organic impurities, clay, silt, salt
or unsound particles. The amount of clay, silt and fine dust present in aggregate,
whether as coatings or separate particles, may not be more than:
15% by weight in crushed sand 3% by weight in natural or crushed gravel sand 1% by
weight in coarse aggregate.
If the Engineer considers that any aggregate which the Contractor proposes to use
contains an excess of fine particles or any harmful substances, the Contractor shall
either replace the aggregate or, at his option and entirely at his expense, institute a
series of approved tests at an approved laboratory to determine the nature and extent
of the fine particles and harmful substances. Following receipt by the Engineer of the
results of the analysis and tests, he will advise the Contractor in writing whether the
proposed aggregate may or may not be used. The Engineer's decision in this respect
shall be final.
Tests to determine the extent of impurities or fine particles shall include (but shall not
be restricted to) the relevant tests specified in BS 882:1992, ASTM. C40-79
(Colormetric test) and ASTM. C33-82.
10.4.3 Sampling
At least four weeks before he envisages first receiving aggregate from any source the
Contractor, in the presence of the Engineer, shall obtain samples for testing. Samples
Sec 10: Building & Civil Engineering Works
10/32
shall be taken in accordance with the procedure quantities laid down in BS 812 and
shall be subjected to those tests which the Engineer considers necessary to
demonstrate the soundness of the material.
Such tests shall be carried out in an approved manner at the Contractor's expense and
may include the manufacture, both in the laboratory and at site, of test cubes or
cylinders to determine crushing strength.
10.4.4 Grading
The Contractor shall ensure that his offer includes the full cost of obtaining and
transporting suitably graded stone aggregates to site.
Grading of aggregates should, together with the required minimum cement content
and water cement ratio, ensure adequate durability, density and characteristic strength
of the finished concrete. The Contractor shall submit in writing to the Engineer the
make up of the mix he proposes to use, together with the grading analysis for the
particular material and any details concerning his or others' experience with the use of
aggregate obtained from the same source.
10.4.5 Cement
Ordinary Portland Cement shall comply with BS 12. The Contractor may obtain
cement, bagged or in bulk, from any approved source in Bangladesh but shall always
submit sufficient samples from each delivery, as required by the Engineer, to ensure
that all cement complies with the minimum requirements of BS 12. All cement shall
be stored in a weathertight shed at least 300mm off the floor. Regular checks shall be
made on the weight of cement in each bag.
10.4.6 Water
All water used in the preparation of concrete for foundations shall be clean, fit for
drinking and free from all earth, vegetable matter and alkaline substances, whetherin
solution or in suspension, and shall comply with BS 3148.
10.4.7 Reinforcing
Where reinforcing is specified in any foundation design, it shall comply with BS 4449
or an approved similar standard. Before any reinforcing is used, the Contractor shall
provide the Engineer with a certified mill certificate, verifying its grade and quality,
and proof test such samples as the Engineer considers necessary. All reinforcement
shall be clean and free from loose mill scale, dust, loose rust and paint, oil or any
other coating which in the opinion of the Engineer may destroy or reduce bond.
10.4.8 Storage
The Contractor shall ensure that all the materials he provides for the preparation of
concrete shall be stored in a manner which prevents contamination by dust, clay,
Sec 10: Building & Civil Engineering Works
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water or any other harmful material.
Heaps of coarse and fine aggregate shall be separated by at least one metre.
Where aggregate is tipped directly onto the ground, the bottom 20cm of the heaps
shall not be used. Bagged cement shall be protected from rain, mixing water or damp
soil during storage/transport. Cement from accidentally split or damaged bags shall
not be used.
Where the Engineer considers it necessary, special precautions shall be taken to
ensure that aggregate stored on site shall remain dust free. Such precautions may
include the bagging of aggregate at the pit if sites are adjacent to dusty roads or if
heavy rain is liable to wash out fine material or saturate the aggregate to an extent
which might influence the water content of a mix.
Where the Contractor establishes central depots for receiving cement prior to despatch
to individual sites, he shall ensure that the cement storage areas are sufficiently raised
above the surrounding ground to prevent contamination of the cement by surface
water. The material from which storage plinths are made shall be approved by the
Engineer.
10.4.9 Design Mix
Prior to ordering any aggregate the Contractor shall inform the Engineer of the
source(s) of his aggregates and deliver samples to the Engineer. The Contractor will
authorise at an approved laboratory tests to show the sieve analyses, relative densities,
moisture content of the samples of aggregate from each source. At least four test
specimens of concrete shall be mixed at an approved laboratory and tested after 7 and
28 days.
Depending on the moisture content of the samples of aggregate the Contractor will
report to the Engineer on the expected water/cement ratio and the aggregate/cement
ratio of concrete to be produced on site.
Following the successful testing of the laboratory samples the Contractor shall make
trial mixes at site (from which he will take at least 4 test specimens) using the
proportions advised to the Engineer (and in the presence of the Engineer) and using
the equipment he intends to use in the normal day to day manufacturing of concrete.
The minimum 28 day crushing strength of any such test specimen shall be not less
than 20.7 N/mm2.
After successful testing of the test specimens made at site, the Engineer may then
approve the source(s) of aggregate and the mix design.
No changes to the approved mix design will be permitted unless the type or source of
aggregate differs from those already tested, in which case further tests at both the
laboratory and at site will be made.
Any concrete placed which does not conform to the approved mix designs, shall be
Sec 10: Building & Civil Engineering Works
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removed and replaced by the Contractor at his own cost.
10.4.10
Mixing and Placing of Concrete
Proportions of aggregates and cement and the quantity of water for each batch of
concrete shall be closely monitored by an experienced mixer operator. Aggregate
shall preferably be weight batched but, where this is not possible, volume batching
shall be permitted, provided that the net volumes of the loading equipment are
approved by the Engineer. Containers for measuring quantities of water shall be
clearly marked and only approved quantities of water shall be used in the manufacture
of concrete.
Mechanical mixers shall be in good condition and well maintained. After loading, the
constituent parts of the concrete shall be mixed together for a period of not less than
two minutes or 30 revolutions of the barrel, whichever is the greater. For mixers with
a capacity greater than 1.5m3 these periods may be increased if the Engineer so
requires.
When the constituents are adequately mixed, the fresh concrete shall be discharged
from the mixer and placed in the foundation with the minimum of delay. Chutes shall
be used to ensure that fresh concrete is not dropped by more than 1.5 metres.
No concrete shall be placed until all form work, installation of parts to be embedded,
and preparation of surfaces involved in the placing have been approved. No concrete
shall be placed in or through water, except with the written permission of the
Engineer, and the method of
depositing such concrete shall be approved by the Engineer. Concrete shall not be
placed in running water and shall not be subjected to the action of running water until
after the concrete has hardened for seven days. All surfaces of forms and embedded
materials that have become encrusted with dried mortar or grout from concrete
previously placed, mud or other foreign material, shall be cleaned of all such refuse
before the surrounding or adjacent concrete is placed. Immediately before placing
concrete, all surfaces of foundations upon or against which the concrete is to be
placed shall be free from standing water, mud and other foreign matter. The surfaces
of concrete which have set, and against which new concrete is to be poured, shall be
thoroughly cleaned to remove all foreign material and laitance, and be saturated with
water immediately before placing concrete. Concrete shall be deposited continuously
and as rapidly as possible until the unit being poured is complete. If for any reason the
work is stopped before completing the unit of operation, a construction joint shall be
installed in accordance with the instructions of the Engineer. Concrete shall be so
deposited as to maintain, until the completion of a unit, a plastic surface
approximately horizontal.
The method and equipment used for transporting concrete shall be such that concrete
having the required composition and consistency will be delivered as near as practical
Sec 10: Building & Civil Engineering Works
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to its final position without segregation or loss of slump. All concrete mixing and
placing equipment and methods shall be subject to approval by the Engineer.
Concrete placement will not be permitted when, in the opinion of the Engineer,
weather conditions or other pertinent factors prevent proper placement and
consolidation.
Bidders are reminded that, as a minimum standard, the following series of inspections
should be carried out by the Contractor before concreting can begin:
1
Formwork coated with mould oil and correct in type, quantity and condition
2
Centre lines of template to coincide at the centre peg
3
Formwork to be well strutted and correctly located
4
Vibrator to be in working order
5
Mixer to be in working order
6
There is provision to maintain continuous mixing and pouring, by hand if
necessary, in the event of a mixer breaking down
7
Where necessary, re-bar is on site ready bent and complete with tie wire, stirrups
and concrete or plastic preformed spacer packs
8
A reliable level is at hand
9
There is sufficient aggregate, cement and water to complete the pour
10 Excavations are safe and not cluttered around the top edges
11 The mixer barrel is clean, and the paddles are complete and in place and the
barrel will rotate at the speed specified by the Manufacturer
12 A suitable chute is in place
13 Both an air thermometer and concrete thermometer are on site
14 There is a large quantity of hessian sacking at hand
Where any of the above items are not complied with, the Engineer may suspend
concreting pending their implementation.
10.4.11
Testing of Concrete
Samples shall be taken and tested in accordance with BS 1881. Testing shall be
carried out by an approved laboratory, who shall arrange to immediately notify the
Contractor and the Employer in writing of any cube failure. Failed cubes shall be kept
for reference.
Concrete for the test specimens shall be taken at the point of deposit. To ensure that
the specimens are representative of the concrete, a number of samples shall be taken
from different points. Each sample shall be large enough to make one test specimen
and shall be taken from one point in the work.
Sec 10: Building & Civil Engineering Works
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The tests specimens shall be stored at the site at a place free from vibration, under
damp sacks for 24 hours + 1/2 hour, after which time they shall be removed from the
moulds, marked and stored in water at a temperature of 10˚ to 21˚C until the test date.
Specimens which are to be sent to a laboratory for testing shall be packed for transit
in damp sand or other suitable damp material, and shall reach the laboratory at least
24 hours before test. On arrival at the laboratory, they shall be similarly stored in
water until the date of the test.
One compression plate of the testing machine shall be provided with a ball seating in
the form of a portion of a sphere, the centre of which coincides with the central point
of the face of the plate. Test specimens shall be placed in the machine in such a
manner that the load is applied to the sides of the specimen as cast.
Cube strengths for concrete are to be not less than 14.8N/mm2 within seven days after
mixing and 20.7N/mm2 within 28 days after mixing.
One cube shall be tested at 7 days to obtain an indication of the concrete strength. The
remaining three cubes shall be tested at 28 days and the average of their strengths
shall be calculated. Should the average of the cube strengths fall below the specified
28 days cube strength, the Engineer may order the affected concrete to be removed
and replaced at the Contractor's expense, or the Engineer may allow the Contractor to
take a cylinder for further testing in accordance with BS 1881, if Schmidt Hammer
readings indicate below strength concrete.
The diameter of the cylinder shall be not less than three times the size of the
maximum aggregate and its length will be at least double the diameter, after allowing
for preparation and facing prior to the test. Both a report and compression test will be
completed for the sample in accordance with BS 1881. Only one such test will be
permitted from any one sample and if the crushing strength of the sample is in excess
of that required by the design the Engineer may, after the Contractor has made
suitable repairs to the part disturbed by taking the sample, accept the concrete.
10.4.12
Formwork
Formwork shall conform to the shape, lines and dimensions of the concrete as called
for on the Plans and shall be sufficiently strong to carry the dead weight of the
concrete without undue deflection or bulging, and sufficiently tight to prevent leakage
of mortar. It shall be properly braced and tied together so as to maintain position and
shape. Members used in forms at exposed surfaces shall be dressed to uniform
thickness and shall be free from loose knots or other defects. Joints in forms shall be
horizontal or vertical. At all unexposed surfaces and rough work, undressed timber
may be used. Timber reused in shutters shall have nails withdrawn and surfaces to be
in contact with concrete thoroughly cleaned before being reused. Formwork shall not
be disturbed until a minimum of 48 hours has passed from time of placement and
concrete has hardened sufficiently to support any construction loads that may be
imposed. When stripping forms, metal wedges or tools shall not be used to pry panels
Sec 10: Building & Civil Engineering Works
10/37
loose. If wedging is necessary, it shall be done with wood wedges lightly tapped to
break adhesion. All columns and beams will have exposed edges chamfered 20 mm x
20mm.
10.4.13
Reinforcing Steel
Steel reinforcing bars shall be positioned in the concrete at the places shown on the
drawings, or where reasonably directed by the Engineer.
Before reinforcing bars are placed in position, surfaces shall be cleaned of heavy
flaky rust, loose mill scale, dirt, grease and all foreign matter. Once in position,
reinforcing bars shall be maintained in a clean condition until they are completely
embedded in concrete. Reinforcing bars shall have at least the minimum concrete
cover shown on the drawings. Reinforcing bars shall be accurately placed and secured
in position, such that they will not move during placing of concrete. Precast concrete
block spacers may be used for supporting reinforcing bars.
10.4.14
Consolidation of Concrete
Concrete shall be consolidated to maximum practical density, without segregation, by
vibration so that it is free from pockets of coarse aggregate and closes against all
surfaces and embedded materials. Vibration of concrete in structures shall be by
electric or pneumatic-driven immersion type vibrators of 50mm minimum diameter,
operating at speeds of at least 8,000rpm when immersed in concrete. The vibrator
shall be inserted vertically at close enough intervals so that the zones of influence
overlap. The vibrator shall be inserted to the full depth of the layer being treated and
withdrawn slowly. When concrete is being placed in layers, the tip of the vibrator
shall extend approximately 100mm. into the underlying layer. Vibrators shall not be
used to move concrete horizontally. Care shall be exercised to avoid over-vibration of
the concrete and direct contact between the vibrator and reinforcing shall be avoided.
10.4.15
Curing of Concrete
For foundations where excavations are to be backfilled immediately following the
striking of shutters, the concrete is to be thoroughly wetted before backfilling
commences. Where shutters are to be struck and backfilling of the excavation is not to
take place immediately, the concrete is to be covered with wetted hessian sacking and
be enclosed in polythene sheeting to avoid rapid drying of the concrete.
10.4.16
Hot Weather Concreting
In hot weather the following additional precautions shall be taken.
(a)
In hot weather suitable means shall be provided to shield the aggregate
stockpiles from the direct rays of the sun or to cool the mixing
water/aggregates to ensure that the temperature of the concrete when
deposited shall not exceed 32˚C.
Sec 10: Building & Civil Engineering Works
10/38
(b)
10.5
In hot dry weather suitable means shall be provided to avoid premature
stiffening of concrete placed in contact with hot dry surfaces. Where
necessary the surfaces, including reinforcement, against which the
concrete is to be placed shall be shielded from the rays of the sun and shall
be sprayed with water to prevent excessive absorption by the surfaces of
water from the final concrete.
WORKMANSHIP OF ALL OTHER MATERIALS
This specification only describes concrete work in detail. All other materials
workman-ship shall be in accordance with an agreed standard. Before starting any
new item of work the Contractor shall submit samples of the materials to the Engineer
for approval in writing and the method of installation shall also be approved. The first
item of any type to be installed shall be inspected and checked in detail by the
Engineer before other items are constructed.
10.6
Land development work :
10.6.1 Land development work shall be carried out by dredged filling material or by
carriedearth/viti sand using the following methods:
(a)
Land development by dredge filling material:
Land development by dredge filling materials means dredging by cutter suction
dredger for collection and direct pumping of dredged fill materials by 18" dia. or more
cutter suction dredgers from the pre-selected river bed through pipe line to the
proposed fill site in wet and liquefied condition. The dredged material will be placed
at site directly and excess water will be removed out of the site. Spreading and
compaction of fill material will be carried out in layers. The layer thickness shall be
determined on the quality of dredged fill material.
(b)
Land development by carried earth/viti sand:
The responsibility of selecting proper location of collection of fill materials (such as
earth/viti sand) will rest on the contractor, subject to the approval of the employer.
The contractor shall obtain prior necessary permission from the concerned
owner/authority paying royalties, all taxes, duties etc. as per prevailing Govt. / semi
Govt. / Autonomous organization rule with the intimation to employer for collecting
the required fill material. In this case mini suction dredger can be used to collect fill
material from nearby river. The crops compensation resulting from the damage of
crops during pipe line installation and any other activities shall be paid by the
Sec 10: Building & Civil Engineering Works
10/39
contractor and the cost deem to be included in the price.
10.6.2 The quoted rates are inclusive of all the costs for supply of materials and hire charges
for equipment and accessories etc. required to execute the works by the Contractor.
10.6.3 Before land filling, The Contractor has to construct necessary dyke/embankment for
protection the developed land.
10.6.4 The rates are inclusive of all the royalties, taxes, VAT, octroi etc. to be paid to Govt.
& semi-Govt. Organization or to any person for the earth borrowed from.
10.6.5 If the Contractor uses the land beyond the control of the Employer, the cost/hire
charges, octroi etc. so required will be paid by the Contractor for carrying, laying &
installation of equipment, tools & pipes etc. over that land.
10.6.6 The Contractor is responsible to obtain the permission/approval from the competent
authority for the works as mentioned in clause no. 4 & 5 above.
10.6.7 The Contractor shall execute the pre-work measurements jointly with the
representative of Employer for the area to be filled prior to start the land development
work.
10.6.8 The Contractor, along with his bid shall furnish the detailed procedure of whole works
with a list of manpower, tools & equipment required to execute the same. He shall, if
the proposal is by dredged filling also show in the drawing location of the river bed to
be dredged and the route of pipe lines from the dredging point to the filling area.
10.6.9 The Contractor shall clean and remove the unspecified & the unsuitable materials
which do not mix with the earth at his own cost and responsibility.
The work may be increased or decreased as per site requirement and no extra price
escalation by the contractor for such increase of work shall be entertained.
10.6.10 The Contractor will arrange the testing of the samples of the fill materials &
compaction tests of developed areas by Laboratory approved by employer. The cost
of any or all such tests shall be borne by the Contractor.
10.6.11The Contractor shall protect & maintain all the materials, equipment etc. against any
theft or damage etc. at his own cost until the final executed works are handed over to
the Employer.
10.6.12 After 30 days of completion of the land development work, the contractor will
arrange the joint survey (Post-work measurement) along with the employer
representative. The quantity of land development shall be calculated by the
contractor and checked by the employer according to this joint post-work
measurement and the pre-work measurement taken prior to start the work (as
mentioned in clause no.7). The rates in the schedule are inclusive of all surveys/pre
& post-work measurements.
10.6.13 The security of the equipment and materials used and the safety of the personnel
engaged in the work shall be at the risk and responsibility of the Contractor.
10.7
Fire Extinguisher :
10.7.1 Control Room/Communication Room/Battery Rooms :
Sec 10: Building & Civil Engineering Works
10/40
These rooms shall be protected by portable CO2 fire extinguisher system. The system
shall consist of all equipment required for directing the CO2 gas discharge at a fire
including, but not limited to, CO2 cylinders and necessary piping, a flexible hose
along with a jet nozzle. The effective reach of CO2 gas jet release shall be sufficient to
fight small fires that could develop in a control room area. Fire extinguishers shall be
placed at strategic locations as per instruction of project engineer. The quantity of
extinguisher at each new substation given in Table-1.
10.7.2 Outdoor Switchyard/Cable Room :
These areas shall be protected by portable dry type ABC powder fire extinguisher
system. The system shall consist of all equipment required for directing the dry ABC
powder discharge at a fire including, but not limited to, a wheel carriage(only for
15kg capacity) loaded with potable cylinders and necessary piping and a flexible hose
along with a jet nozzle & pressure gauge. The extinguisher material shall be nonexplosive, non-hazardous, non-corrosive, non toxic. The effective reach of jet release
shall be sufficient to fight small fires that could develop in an outdoor switchyard,
cable room & store room area. Fire extinguishers shall be placed at strategic locations
as per instruction of project engineer. In addition sand buckets also shall be provided
with a metal frame for hanging buckets and shall be placed at locations directed by
project engineer. The quantity of extinguisher at each new substation given in Table1.
Table-1: The quantity of fire extinguisher shall be provided at each new substation as
follows:
Sl
No
Description
Quantity
CO2 Type:
1
3kg
5Nos.
5kg
5 Nos.
ABC dry powder type:
2
3
5kg
6 Nos.
8kg
4 Nos.
15kg(including wheel carriage)
3 Nos.
Sand bucket with metal frame
One(1)set with 5 buckets
Sec 10: Building & Civil Engineering Works
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SECTION 10 – APPENDIX A
HOLD POINTS
Clause Reference
10.1.10
10.3.2
10.3.4
10.3.8
10.3.9
10.3.18
10.3.28
10.4.9
10.5
Hold Points
Concrete placement
Waterproofing
Site investigation
Road pavement
Water supply
Installation of GIS entrance gate
Curing compounds
Concrete mix design
Method statement
Sec 10: Building & Civil Engineering Works
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POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 11
SUPPORTING STRUCTURES FOR OUTDOOR EQUIPMENT
SECTION 11
SUPPORTING STRUCTURES FOR OUTDOOR EQUIPMENT
TABLEOF CLAUSES
11.1 SCOPE ................................................................................................................... 11/3
11.2 STRUCTURE ARRANGEMENT....................................................................... 11/3
11.3 DESIGN ................................................................................................................. 11/3
11.3.1General ............................................................................................ 11/3
11.3.2Assumed Loading Combinations .................................................... 11/4
11.3.3Line Termination Structures ........................................................... 11/5
11.3.4Partial Load Factors ........................................................................ 11/5
11.3.5Wind Loading ................................................................................. 11/5
11.3.6Equipment and Conductor Terminations ........................................ 11/6
11.3.7Safety and Access Requirements .................................................... 11/7
11.3.8Structural Design ............................................................................ 11/8
11.3.9Design Submissions ........................................................................ 11/9
11.4 MATERIALS ........................................................................................................ 11/9
11.5 WORKMANSHIP .............................................................................................. 11/10
11.6 PROTECTIVE TREATMENT ......................................................................... 11/10
11.7 QUALITY CONTROL....................................................................................... 11/10
11.7.1General .......................................................................................... 11/10
11.7.2Welding ......................................................................................... 11/11
11.7.3Check Erection .............................................................................. 11/11
11.7.4Galvanising ................................................................................... 11/11
11.7.5Tolerances ..................................................................................... 11/12
11.8 ERECTION ......................................................................................................... 11/12
SEC 11: Supporting Structures for Outdoor Equipment
11/1
SEC 11: Supporting Structures for Outdoor Equipment
11/2
SECTION 11
SUPPORTING STRUCTURES FOR OUTDOOR EQUIPMENT
11.1
SCOPE
Where specified structures shall be provided under this contract for supporting the
conductors, busbars, insulators, isolating switches, circuit breakers, current and
voltage transformers, surge arresters, line traps, coupling capacitors, sealing ends
or cable boxes and cables where necessary and other items of plant generally as
shown on the relevant drawings. Facilities shall also be provided where specified
for the termination of the incoming transmission lines.
All structure designs shall be such as to facilitate inspection, painting,
maintenance, repairs and operation with the continuity of supply being the prime
consideration.
11.2
STRUCTURE ARRANGEMENT
The arrangement of the high level structures supporting conductors and/or busbars
shall be either lattice structures primarily composed of angle sections, or low visual
impact A-frame type structures primarily composed of welded hollow or composite
sections. Angle, hollow or composite sections shall be either steel or aluminium as
specified. For lattice structures a fully triangulated system of bracings shall
preferably be adopted. For A-frame structures the primary connections between
major components shall be bolted, for ease of transportation and erection.
Low level support structures shall be either lattice structures primarily composed of
angle sections or 'moment' type structures primarily composed of welded hollow or
composite sections.
The design and arrangement of supporting structures shall be subject to approval
by the Engineer.
The type of arrangement of high level structures and acceptable materials for both
high and low level structures shall be as specified in the Schedule of Technical
Requirements.
11.3
11.3.1
DESIGN
General
The supporting structures shall be designed to ensure that the specified minimum
phase, earth and section clearances are maintained under all conditions. Where
applicable special attention shall be paid to the design of the line termination
structures to ensure minimum phase clearance is obtained for the complete range of
angles of entry specified.
The strength and rigidity of structures shall be such that the alignment of the
SEC 11: Supporting Structures for Outdoor Equipment
11/3
equipment which they carry shall not be affected by the static and dynamic loads to
which the structures are subjected.
The assumptions made in the overall structural design especially in the load
transfer between the gantry beam and column shall be adequately reflected in the
design and detailing of the beam-column connection.
11.3.2
Assumed Loading Combinations
The supporting structures shall be designed to resist the ultimate applied loading,
determined in accordance with the following load combinations:
Load Combination 1 - Design Wind, Coincident Temperature, (Ice)
(a) The wind pressure specified in the Schedule of Technical Requirements
Appendix 11of this Section, applied to the projected area of all conductors and
electrical equipment;
(b) The wind pressure specified in the Schedule of Technical Requirements
applied to the projected area of all members of the windward face of structure;
(c) Where appropriate the conductor and/or earthwire tensions or busbar forces,
including
due
allowance
for
both
horizontal
and
vertical
deviations/inclinations;
(d) Self weight of the equipment and structure;
(e) When stated in the Schedule of Technical Requirements the effects of the
specified
radial ice thickness shall be taken into account in the
determination of the wind area of the conductor, earthwire, busbar, electrical
equipment and the supporting structure, the conductor and earthwire tensions
and the self weight of the equipment and the structure.
The wind directions considered shall include transverse, longitudinal and if
appropriate 45˚ to the major axis of the structure.
Load Combination 2 - Still Air, Short Circuit, Minimum Temperature or
Maximum Operating Temperature
(a) Conductor and/or earthwire tensions or busbar forces including the dynamic
affects calculated in accordance with IEC 865-1.
(b) Self weight of the equipment and structure;
SEC 11: Supporting Structures for Outdoor Equipment
11/4
Load Combination 3 - Still Air, Seismic, Coincident Temperature (Ice)
(a) Conductor and/or earthwire tensions or busbar forces;
(b) Seismic forces;
(c) Self weight of the equipment and structure;
(d) When stated in the Schedule of Requirements the effects of the specified radial
ice thickness.
Seismic forces shall be applied as a static horizontal force transversely and
alternatively longitudinally to the major axis of the structure, and shall be equal in
value to the seismic coefficient stated in the Schedule of Technical Particulars
multiplied by the self weight of the conductor, earthwire, busbar, electrical
equipment and structure, and applied at the centre of gravity of the equipment and
structure as appropriate.
Load Combination 4 - Still Air, Erection, Coincident Temperature
(a) Conductor and/or earthwire tensions or busbar forces;
(b) Self weight of the equipment and structure.
For erection conditions any one complete phase conductor bundle or busbar or
earthwire shall be assumed not to be erected in any one span.
For the purposes of design all high level structures shall be considered as terminal
structures. For multi-bay continuous structures, central columns shall be designed
for the most onerous condition of adjacent bays being loaded or unloaded.
11.3.3
Line Termination Structures
For details of the incoming transmission line phase conductor and earthwire
details, and angles of entry reference should be made to the Schedule of Technical
Requirements.
11.3.4
Partial Load Factors
The partial load factors to be applied to the loading combinations determined in
accordance with Clause 11.3.2 shall be as specified in the Schedule of Technical
Requirements.
11.3.5
Wind Loading
SEC 11: Supporting Structures for Outdoor Equipment
11/5
The reference wind pressure to be adopted for the design of the outdoor supporting
structures shall be based upon the value specified in the Schedule of Technical
Requirements. The reference wind pressure qref N/m2 at a height of 10m above
ground level shall be subjected to variation for height and shape of the structure or
equipment under consideration to give the total wind load.
The total wind load on the structure or equipment surface shall be determined from
the expression:
The total wind load on the structure or equipment surface shall be determined from
the expression:
Fw = qref
where
H 2α
Cshp WA
10
Fw
=
The calculated total wind load on the structure or equipment:
q ref
H
α
Cshp
WA
=
=
=
=
=
reference wind pressure
Height to top of the panel under consideration
power law index
aerodynamic shape factor
windward face area of the structure or equipment
The aerodynamic shape factor Cshp shall be as specified:
Flexible conductors
Earthwires
Tubular busbars Re < 4.1 x 105
4.1 x 105< Re < 8.2 x 105
Support insulators, porcelain for apparatus or
cap & pin insulator strings
Flat truss structures consisting of profiles
Square & rectangular lattice towers & supports
consisting of profiles
Sharp edged structures & components other than above
Flat truss structures consisting of tubes
Square & rectangular lattice towers & supports
consisting of tubes
Notes:
11.3.6
1.0
1.2
1.2 [1]
0.6
1.2 [2]
1.6
2.8
2.0
1.2
2.1
[1] Re = Reynolds Number
[2] Based on external diameter of insulator.
Equipment and Conductor Terminations
All supporting structures shall be provided with such holes, bolts and fittings as
SEC 11: Supporting Structures for Outdoor Equipment
11/6
may be necessary to accommodate insulators, isolating switches and other
equipment provided under the Contract.
Where incoming transmission lines and/or conductors and/or earthwires are
terminated at structures with tension sets, approved shackle or swivel attachments
shall be provided. To facilitate maintenance and erection, additional attachment
points shall be provided adjacent to the main termination attachment. The supply
and connection of the incoming transmission line will be undertaken under a
separate contract.
Structures required to support cable sealing ends shall be provided with
arrangements for supporting the cables. Attachment holes for the connection of
earthwire bonds shall be provided adjacent to the earthwire attachment point.
Attachment holes for the connection of the substation earthing grid shall be
provided on the vertical face of the structure, approximately 300mm above the top
of concrete. Foundation holding-down bolts shall not be used for the attachment of
earth connections.
11.3.7
Safety and Access Requirements
To facilitate safe inspection and maintenance all supporting structures which
cannot be maintained from ground level shall be provided with climbing facilities,
inter-circuit screens, guards etc in appropriate positions as agreed with the
Engineer.
All members inclined at 40˚ or less to the horizontal, shall be designed to resist a
mid-point load of 1.5 kN, with no other loading being considered.
Where specified step bolts of an approved type shall be fitted to supporting
structures at not more than 450 mm centres starting as near as practicable to the
base and continuing to within 1m below the top of the structure. It shall be noted
on the erection drawings that all step bolts are to be removed after construction for
a distance of 2.0m above ground level. Adequate clearance shall be provided
between the step bolts and any obstructions which might interfere with their use.
Step bolts shall not be less than 16mm diameter, project not less than 150mm, and
be fixed with nut, washer and nut.
Where specified ladders of an approved type generally in accordance with the
requirements of BS 4211, 450mm wide and 350mm rung spacing shall be fitted to
supporting structures. They shall be incorporated into the structure either integrally
or separately. Where specified cage protection or fall arrest systems shall be fitted
to the ladder. Means shall be provided to prevent unauthorised access of ladders.
SEC 11: Supporting Structures for Outdoor Equipment
11/7
Intercircuit screens shall be provided where necessary to prevent access between
adjacent circuits on multi-bay structures. Inter-circuit screens shall be fabricated
from a 50mm x 50mm mesh formed from 3mm diameter galvanised steel wire.
All structures shall be fitted with identification/notice plates as appropriate.
11.3.8
Structural Design
The allowable ultimate unit stresses used in the determination of the nominal
member strength of supporting structures shall be based on the following:
Lattice steel structures
Steel A frame or moment structures
Aluminium structures
ANSI/ASCE 10-90
BS 5950
BS 8118: Part I
Partial factors to be applied to member nominal strength determined in accordance
with the above stated codes shall be as specified in the Schedule of Technical
Requirements. For ANSI/ASCE 10-90 the appropriate reference stress levels shall
be based on the values specified in BS 5950.
The maximum allowable slenderness ratios shall not exceed the following:
For column or support leg members, beam chords
For other load bearing compression members
For secondary (redundant bracings)
For tension only members
Steel /Aluminium
120
200
250
350
Members shall be of such shape, size and length to preclude damage or failure
from vibration or stress reversal, including the detailing of connections.
Minimum member thickness and diameter of bolts shall be as specified in the
Schedule of Technical Requirements
Holding down bolts shall be used to connect the structures to their foundations.
The design of holding down bolts shall make adequate provision for combined
axial and shear forces.
The nuts of all bolts attaching conductors, busbars or earthwire tension sets etc,
shall be locked with a locknut. No screwed threads shall form part of a shearing
plane between members, and bolts shall not project more than 10mm beyond the
nut.
SEC 11: Supporting Structures for Outdoor Equipment
11/8
11.3.9
Design Submissions
The Contractor shall submit all design calculations, drawings and method
statements as required. All sets of calculations shall be complete, bound, properly
titled and given a unique drawing number. An agreed system of identification of
the structure design reference, fabrication drawings and substation general
arrangement drawings shall be used.
Calculations shall contain a Design Information sheet, derivation of all applied
loadings including sag and tension and dynamic tension calculations, the design
load for each member group under the critical loading case, member size,
slenderness ratio, allowable load, end connection detail and foundation load
schedule. Codes or standard references should be quoted and where computer
programs are used, a full explanation in the English language shall be provided to
assist the Engineer's approval of the calculation.
11.4
MATERIALS
All steel shall comply with BS EN 10025 or BS EN 10210 as appropriate and shall
be suitable for all usual fabrication processes including hot and cold working
within the specified ranges. The Contractor must take due cognisance of the
minimum ambient temperature, quality of steel, charpy impact value and stress
relieving.
The quality of finished steel shall be in accordance with BS EN 10163. All steel
shall be free from blisters, scale, lamination, segregation's and other defects. There
shall be no rolling laps at toes of angles or rolled in mill scale.
Hot rolled steel plate 3mm thick or above shall be in accordance with the
requirements of BS EN 10029.
Bolts and nuts shall be ISO Metric Black Hexagon to BS 4190 and shall be
threaded ISO Metric
Course Pitch to BS 3643: Part 2, Tolerance Class 7H/8g. Only one grade of steel
shall be used per bolt diameter. Washers shall be in accordance with BS 4320
Grade E and BS 4464 Type B as appropriate.
Consumables used in metal arc welding shall be in accordance with the relevant
standard.
All materials for aluminium. structures shall be in accordance with BS 8118: Part
2.
SEC 11: Supporting Structures for Outdoor Equipment
11/9
11.5
WORKMANSHIP
The Contractor shall submit panel assembly (fabrication) drawings which shall
show all materials in place, complete with all fabrication and connection details. A
complete tabulation listing all pieces, bolts, nuts, washers etc shall also be shown
on the drawings. The Contractor shall make changes to the fabrication details
which the Engineer determines necessary to make the finished structure conform to
the requirements and intent of the specification.
The Contractor shall submit a detailed Method Statement of his proposed
fabrication procedures including quality control procedures to ensure satisfactory
assembly and erection, interchangeability of similar members, accuracy of
dimensions, position and alignment of holes.
All welding shall be carried in accordance with BS 5135 for steel structures and BS
8118 Part 2 for aluminium structures. All members shall be stamped on before
galvanizing or other protective coatings, using characters 10mm high and shall be
clearly legible after galvanizing.
11.6
PROTECTIVE TREATMENT
Unless otherwise specified after fabrication, all structural steelwork, including
bolts, nuts and washers shall be hot dipped galvanized to meet the requirements of
BS 729. Bolt threads shall be cleaned of surplus spelter by spinning or brushing.
Dies shall not be used for cleaning threads other than on nuts. Nuts shall be
galvanized and tapped 0.4mm oversize and threads shall be oiled.
Excessively thick or brittle coatings due to high levels of silicon or phosphorous in
steel, which may result in an increased risk of coating damage and/or other features
that make the final product non-fit-for purpose shall be cause for rejection.
Protective treatment for aluminiurn shall be in accordance with the requirements of
BS 8118.
Galvanizing thickness and aluminium protection procedure shall be as specified in
the Schedule of Technical Requirements
11.7
11.7.1
QUALITY CONTROL
General
Routine tests on raw materials and fabricated individual members shall be
undertaken in accordance with BS EN 10025, BS EN 10210 and BS 8118 as
appropriate.
All steel ex-mills or received from merchant's stock shall be marked to identify the
cast or casts from which it was rolled in accordance with Section 9 of BS EN
SEC 11: Supporting Structures for Outdoor Equipment
11/10
10025 and Section 10 of BS 102 10, and shall be covered by the appropriate (mill)
certificate. The optional impact test BS EN 10210 option 1.6 for quality JO is
required.
The material grades or alloy categories of individual pieces of steel/aluminium
shall be capable of positive identification at all stages of the fabrication process.
Bolts and nuts shall be covered by the appropriate test certificate to prove
compliance with BS 4190.
11.7.2
Welding
Unless specified to the contrary all structural welds shall be undertaken using
approved welding procedures in accordance with BS EN 288. All welders shall be
tested to the requirements of BS EN 287.
All welding shall be subject to a non-destructive testing (NDT) programme, which
shall include visual, ultrasonic and magnetic particle testing as appropriate. Visual
inspection shall be in accordance with BS 5289, ultrasonic to BS 3923 and
magnetic particle to BS 6072. Acceptance criteria shall be in accordance with BS
5135, except for porosity and BS 8118: Part 2. All welds especially butt welds
must be continuous to ensure a pickle-tight connection when galvanised.
The Contractor's NDT programme shall be submitted to the Engineer for approval
prior to the commencement of fabrication.
11.7.3
Check Erection
Prototype structures shall be check erected in order to verify the accuracy of
detailing and fabrication.
The degree of check erection shall be sufficient to verify not only the main
structure, but all auxiliary steelwork. Sufficient blocking and support shall be
provided to prevent distortion and overstressing of members to ensure proper fit.
Assembly shall be accomplished without extraordinary effort to align bolt holes, or
to force pieces into position. Bolt holes shall not be reamed or enlarged. Any
damage to protective coatings during check erection if the check erection is
undertaken on coated structures, shall be recoated at the fabricator's cost.
11.7.4
Galvanising
Tests on galvanised members and components shall be carried out at the works to
ensure compliance with the requirements of BS 729.
SEC 11: Supporting Structures for Outdoor Equipment
11/11
11.7.5
Tolerances
The fabrication tolerances after galvanising for steel members, which are not to be
considered cumulative shall be as follows:
(a) On linear dimensions of nominal sections as per BS 4, BS 4848, BS EN
10024, BS EN 10034 & BS EN 10056-2.
(b) On overall length of member ± lmm
(c) On centres of holes
± lmm
(d) On groups of holes
± 2mm
(e) On back-gauges
± lmm
(f) On corresponding holes in opposite faces of a member
± lmm
(g) On specified hole diameter on the punch side (in the black), ± 0.3%
or when drilled
-0mm
(h) Taper on the punched holes as measured between the specifiedhole diameter
on the punch side and the hole diameter on the die's side (in the black)
±
l.0mm
(i) On specified bends, open and closed flanges ± 0.02%
The pennitted tolerances for straightness after galvanising shall not exceed an
offset of 1: 1000.
Tolerances for aluminium structures shall be in accordance with BS 8118: Part 2.
11.8
ERECTION
The Contractor shall when requested provide the Engineer with a Method
Statement detailing his proposed erection methods. Due cognisance shall be taken
of the relevant parts of BS 5531 and current health and safety legislation.
All structural members stored on site shall be kept clear of the ground where
possible. Contact with substances likely to attack the protective coatings shall be
avoided and all members kept in a clean and tidy condition. Care shall be taken to
prevent damage/deterioration of any protective coating during transportation,
storage and erection. Unless otherwise agreed damaged members shall be replaced.
The renovation of damaged areas of protective coatings shall be carried out using
techniques agreed with the Engineer.
The Contractor shall ensure that the structures are not strained or damaged in any
SEC 11: Supporting Structures for Outdoor Equipment
11/12
way during erection. Structures shall be erected vertically within a tolerance at the
top, or the centre of the beam of 0.5% of the overall structure height before
equipment installation or conductor/busbar stringing.
SEC 11: Supporting Structures for Outdoor Equipment
11/13
APPENDIX TO SECTION 11
Line
1.
2.
Description
Structure Arrangement [clause 11.2]
High Level
Low Level
Primary Material
Lattice or A-Frame
Lattice or Moment
Steel
Load Combination 1 [clause 11.3.2]
Wind pressure at above G.L. qref
Power Law factor
Coincident temperature
Radial ice thickness
kN/m2
α
˚C
Structures
only
3.54
0
StructuresBusbars
etc.
1.21
0.095
5
0
mm
Density of ice
kg/m3
Load Combination 2
Minimum temperature
Maximum operating temperature
Load Combination 3
Seismic coefficient
Coincident temperature
3.
4.
-
˚C
˚C
5
80
˚C
0.2g
5
Line Termination Structure [clause 11.3.3]
Phase
Earthwire
Conductor Designation
Type
Number of sub-conductors
Maximum working tension per SubconductorkN
Radial ice thickness
mm
Maximum downlead span
m
Maximum angle of entry horizontal
deg.
Vertical
deg.
Low duty tension set wind area
m2
Mass
kgs
Mallard
ACSR/SA
2
7.0
0
7 x 4.0
GSW
4.5
0
75
45
75
45
0-30
0-30
0.7
-
100
-
Steel
1.35
1.0
Aluminium
N/A
N/A
Partial Load Factors [clause 11.3.4]
Load Combination
1
2
SEC 11: Supporting Structures for Outdoor Equipment
11/14
Line
Description
3
4
1.0
1.5
N/A
1.5
SEC 11: Supporting Structures for Outdoor Equipment
11/15
Line
5.
6.
Description
Safety and Access Requirements [clause
11.3.7]
Step bolts
Ladders:
Cage protection
Fall arrest system
High Level
Low Level
YES
YES
NO
NO
NO
NO
NO
NO
Partial Material Factors [clause 11.3.8]
Steel
Aluminium
Foundations
7.
8.
0.85
0.76
Minimum Member Thickness [clause 11.3.8]
Main member
mm
Other bracing members
mm
Secondary (redundant) members
mm
Plates
mm
mm
Bolt diameters
mm
Minimum thickness specified shall apply to both
hot rolled and hollow sections
Steel
6.0
5.0
5.0
6.0
Aluminium
N/A
16.0
Protective Treatment [clause 11.6]
Galvanising thickness
Protection procedure
µm
85
N/A
BS 729
No
SEC 11: Supporting Structures for Outdoor Equipment
11/16
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 12
LIGHTING, SMALL POWER, HEATING AND VENTILATION
SECTION 12
LIGHTING, SMALL POWER, HEATING AND VENTILATION
TABLEOF CLAUSES
12.1 SCOPE ................................................................................................. 12/3
12.2 REFERENCES..................................................................................... 12/3
12.3 DEFECTS LIABILITY PERIOD .......................................................... 12/4
12.4 APPROVALS........................................................................................ 12/4
12.5 LIGHTING REQUIREMENTS ............................................................ 12/4
12.6 SCHEDULE OF DESIGN REQUIREMENTS ..................................... 12/5
12.7 CODING SYSTEMS............................................................................. 12/6
12.8 DISTRIBUTION BOARDS .................................................................. 12/6
12.9 MINIATURE CIRCUIT BREAKERS ................................................... 12/7
12.10 CABLES .............................................................................................. 12/7
12.11CABLETERMINATIONS .................................................................... 12/8
3.12 SEALING AND DRUMMING .............................................................. 12/9
12.13CONDUIT ............................................................................................ 12/9
12.14CABLETRUNKING ............................................................................12/13
12.15CABLETRAYS ....................................................................................12/13
12.16CABLEJOINTING ..............................................................................12/14
12.17CONTACTORS ...................................................................................12/14
12.18SWITCHESANDPUSHBUTTONS .....................................................12/14
12.19LIGHTINGFITTINGS ........................................................................12/15
12.20LAMPS ................................................................................................12/16
12.21 SOCKETOUTLETSAND
12/16
FUSED
SPUR
OUTLETS
12.22 TIMESWITCHES...............................................................................12/17
12.23 POLES ...............................................................................................12/17
12.24INTERIORINSTALLATIONS.............................................................12/17
12.25 EXTERIORINSTALLATION .............................................................12/18
12.26 EMERGENCYLIGHTING .................................................................12/19
12.27 TELEPHONESYSTEM ......................................................................12/19
12.28 SCHEDULE OF LIGHTING FITTINGS AND SOCKET OUTLETS
12/19
SEC 12: Lighting, Small power, Heating and Ventilation
12/1
12.29SCHEDULEOFLIGHTINGREQUIREMENTS...................................12/21
12.29.1Control Building ........................................................... 12/21
12.29.2 Outdoor Areas .............................................................. 12/22
12.30AIRCONDITIONINGANDVENTILATION ........................................12/22
12.30.1Scope of Work................................................................ 12/22
12.30.2Heating .......................................................................... 12/22
12.30.3Air Conditioning ........................................................... 12/22
12.30.4Mechanical Ventilation ................................................ 12/23
12.30.5Basis for Design ............................................................ 12/23
12.30.6Air Cooled Condensing Units ....................................... 12/24
12.30.7Refrigeration Systems .................................................. 12/25
12.30.8 Console Air Conditioning Units .................................. 12/26
12.30.9Ductwork ....................................................................... 12/27
12.30.10 Condensate Drains .................................................... 12/27
12.30.11Extract Ventilation Units ........................................... 12/27
12.30.12Air Filters .................................................................... 12/28
12.30.12Grilles and Louvres .................................................... 12/28
12.30.14Control Equipment ..................................................... 12/29
12.30.15Electrical Connections ................................................ 12/29
12.30.16Manufacturers ............................................................ 12/29
12.30.17Standards .................................................................... 12/29
12.30.18Approval ...................................................................... 12/30
12.30.19Maintenance ............................................................... 12/30
12.31EARTHINGANDBONDING ...............................................................12/30
12.32 CCTV Camera ....................................................................................12/30
12.32 TESTING AND COMMISSIONING ..................................................12/30
SEC 12: Lighting, Small power, Heating and Ventilation
12/2
SECTION 12
LIGHTING, SMALL POWER, HEATING AND VENTILATION
12.1
SCOPE
This section of the Specification includes for the interior and exterior lighting, small
power, heating and ventilation systems and CCTV camera systems.
Whenever practicable, fixtures shall be sourced locally. All lamps, fittings, plugs,
sockets and general accessories of the same size and types shall be similar and
interchangeable throughout the installation.
The lighting and small power equipment and installation shall comply with other
sections of this Specification as appropriate.
All civil works associated with this section of the works shall be deemed to be
included as part of the works in this section. No additional payments will be made
for such requirements.
The requirements of this section of the works are subject to the Main Conditions
and Specifications laid down in other sections of the Bid Document.
12.2
REFERENCES
Any international standards referenced in the specifications and our outdated shall
be replaced with the corresponding replacement.
British Standards
BS 7671
BS 6004
BS 6346:1989
BS 6500
BS 6121
BS EN 60947
BS 4533
BS 3677
BS 1363
BS 1362
BS 4568
BS 4066
Code of Practice Regulations for Electrical Equipment in
Buildings 15th Edition. Institution of Electrical Engineers.
Specification for PVC insulated cables (non armoured) for
electric power and lighting
Specification for PVC insulated cables for electricity supply
Specification for insulated flexible cords and cables
Mechanical cable glands
Specification for control gear for voltages up to and including
1000V AC and 1200V DC
Luminaries
Specification for high pressure mercury vapour lamps
Specification for 13A fuse plugs and switched and unswitched
socket outlets
Specification for general purpose fuse links for domestic and
similar purposes (suitable for use in plugs)
Specification for steel conduit and fittings with metric threads
of 150 form for electrical installation
Test on Electric cable under fire conditions.
SEC 12: Lighting, Small power, Heating and Ventilation
12/3
BS 4434
BS 5970
BS 848
BS 6540
BS 2871
BS 1470
12.3
Specification for safety aspects in the design construction and
installation of refrigerating appliances and systems.
Institution of heating and ventilation Engineers Guide to
current practice.
American Society of Heating Refrigeration and air
conditioning Engineers
Recommendations
Heating and Ventilation Contractors Association of U.K.
specification DW/ 121
Code of Practice for thermal insulation of pipe work and
equipment
Fans for general purposes
Method of test for atmospheric dust spot efficiency and
synthetic dust weight arrestance
Specification for copper and copper alloys: tubes
Specification for wrought aluminium and aluminium alloys for
general engineering purposes, plate, sheet and strip
DEFECTS LIABILITY PERIOD
The Contractor shall be responsible for the efficient and good working of the
installations comprising this section of the Specification for the agreed period as set
out in the Specification document.
12.4
APPROVALS
The Contractor shall submit to the Engineer for approval copies of all his
calculations forming the basis for the designs of the specified systems which shall
be shown on the working drawings, also to be submitted for approval.
Any approvals shall not, however, relieve the Contractor of his contractual
responsibilities which include obtaining local authority approvals for electrical
wiring installations.
12.5
LIGHTING REQUIREMENTS
The lighting installations shall be designed to give the standard service illuminations
and shall incorporate emergency lighting where indicated. Control rooms, relay
rooms, telecommunications equipment rooms, offices and stores shall have the
service illumination measured at 850 mm above finished floor level. All other areas
shall have the service illumination measured at floor level.
The installations shall also meet the limiting glare index requirements as set out in
the specified codes of practice. This section of work gives proposals for the types of
lighting fittings to be used in the area, type of control to be employed, number of
socket outlets and the types of mounting expected to be suitable for the respective
SEC 12: Lighting, Small power, Heating and Ventilation
12/4
areas. Where discharge and fluorescent light sources are to be used in areas
containing rotating or reciprocating machinery, the fittings shall be allocated
between the 3 phase and neutral in such a manner as to avoid stroboscopic effects.
When 3 phase lighting installations are to be used, contactor switching controlled by
pushbuttons located in the area to be illuminated is preferred.
In all rooms and corridors having two entrances the lighting installation shall have
two way switching, the switches being located in appropriate positions adjacent to
the entrances.
Emergency lighting shall be arranged to illuminate all stairways, exits and entrances
and provide some illumination in operational areas within the control building and
the switchyard, e.g. circuit-breaker and transformer locations.
Security lighting shall be installed around the perimeter walls illuminating the
external area and shall be controlled from the gatehouse. The level of illumination
for security lighting shall be measured at a distance of 3 metres outside the
boundary wall.
12.6
SCHEDULE OF DESIGN REQUIREMENTS
The lighting system shall include provision for ease of erection, maintenance,
cleaning, lamp replacement and future extension. Lamp replacement and
maintenance should, unless otherwise approved, be possible without necessitating
outages on main plant items.
Lighting apparatus shall be of top quality, designed to ensure satisfactory operation
and service life under all variations of load, frequency and temperature. Sodium
discharge lighting shall be used for road and security lighting. Switchyard
floodlighting shall use 500W Halogen lamps unless otherwise specified.
Key to Abbreviations:
L
Local switches
S1, S2 etc. Socket outlets or fused spur circuits
P.B
Pushbutton for remote control
T.S
Time switch control
C
Ceiling mounted
W
Wall mounted
P
Pole or earth mast mounted
M
Recessed modular mounting
D
Suspended
F
Flush installation
S
Surface installation
A
Automatic on mains failure.
SEC 12: Lighting, Small power, Heating and Ventilation
12/5
BH
12.7
Behind ceiling diffuser.
CODING SYSTEMS
The Contractor shall, when preparing drawings showing the respective designs, use
a code to identify each lighting fitting and socket outlet.
The code shall comprise letters and figures so compiled that the following
information can be readily identified:-
12.8
1.
The lighting distribution board to which the fitting or socket outlet is
connected.
2.
If connected to the normal supplies or to the emergency DC supplies.
3.
The circuit number and phase of the distribution board to which the fitting is
connected.
4.
The sequence of the fitting in a particular circuit.
DISTRIBUTION BOARDS
The distribution boards and all component parts shall be manufactured and tested in
accordance with the latest standards and designed to suit the fault level of the
transformers supplied. The Contractor shall demonstrate by calculation that this has
been complied with.
Each, current carrying component shall be so designed that under continuous rated
full load conditions in the climatic conditions at Site the maximum total
temperatures permitted under the relevant Standards are not exceeded.
Each distribution board shall have a rustproof metal case of sheet steel with either a
galvanised or enamelled finish. The colour of the enamel finish shall match the
colour of other switchgear. The metal casing is to be provided with a number of
knock-outs or other approved form of cable entries, corresponding to the circuit
capacity of the distribution board, and a suitable screened brass earthing stud.
Busbars, including neutral bar, shall be of high conductivity copper supported to
withstand all normal and fault condition stresses.
All busbars, neutral bars and primary conductors are to be PVC sleeved in
respective phase and neutral colours.
Distribution boards for exterior use shall be galvanised and weatherproof.
Neutral bars shall have an appropriate number of ways relative to the size of the
board. They shall have a rating not less than that of the associated phase busbars.
The metal surface adjacent to any live part and all spaces between phases shall be
protected by barriers of fireproof insulation material.
The distribution boards shall be either single pole or triple pole and neutral types
SEC 12: Lighting, Small power, Heating and Ventilation
12/6
and shall be equipped with means to provide overcurrent protection to each circuit.
This protection may comprise an HRC fuse or a miniature circuit breaker, both of
which shall be removable without exposing live connections.
Fuse bases and bridges, where used, shall be of an approved non- hygroscopic
insulation suitable for the receipt of HRC fuses.
Residual current circuit breakers shall be incorporated to protect all lighting circuits,
socket outlets and supplies to appliances, etc. These shall comply with the
requirements of the main electrical part of this Specification.
The current rating of the busbars in each distribution board is not to be less than the
sum of maximum current rating of all outgoing circuits. The neutral connection for
each circuit is to be direct to the neutral busbar.
Title labels of an approved type and inscriptions are to be fitted externally on the
front cover of each distribution board giving details of the points controlled by each
circuit. The circuit lists shall be typed or printed stating the location of the
equipment served, rating of the protective unit and the circuit loading. The lists shall
be mounted on the inside of the cover door and shall be protected by an acrylic sheet
slid into a frame over the circuit lists. The lists and cover are to be easily removable
to permit circuit modifications.
The cables feeding the distribution boards will be connected directly to the
incoming isolator or neutral bar as appropriate, unless otherwise indicated by the
Specification.
Switchfuse units or isolators connected on the incoming side of a distribution board
shall be mechanically attached to the board with solid copper electrical connections
between the units. A suitable insulated barrier is to be supplied to prevent copper or
carbon dust released under fault conditions passing from one unit to the other.
Distribution boards for use on the direct current system shall be double pole types
equipped with adequately rated fuses.
Mixed capacity boards shall be employed and all contactors and time switches
associated with the respective outgoing circuits shall be accommodated within the
distribution board.
12.9
MINIATURE CIRCUIT BREAKERS
Miniature circuit breakers shall comply with the requirements of the main electrical
part of this Specification.
12.10
CABLES
Cables shall be XLPE insulated, single wire armoured and PVC sheathed overall
and be manufactured and tested in accordance with the requirements of BS 5467,
SEC 12: Lighting, Small power, Heating and Ventilation
12/7
600/1000V grade or equivalent. The outer sheath shall be coloured black and
incorporate flame retardant characteristics to meet the requirements of BS 4066 and
IEC 60332. Jute fillings will not be permitted. Cables shall comply with the
requirements of the cable section of this Specification.
Flexible type cables for pendant cords and final connections to fixed apparatus are
to be butyl or silicone rubber insulated and sheathed, manufactured and tested in
accordance with the requirements of BS 6500, 300/500V or 300/300V grade as
applicable.
The conductor is to comprise multi-strands of 0.25 mm wire. The number of strands
are to be not less than 30 and in all cases of a number suitable for the protection
rating of the respective circuits.
All cables used for lighting and small power shall have copper conductors.
The Contractor is to select conductor sizes for the respective final circuits to meet
the following conditions:(a) That the minimum conductor size for lighting circuits is to be 1.5 mm2 and for
socket outlets 2.5 mm2.
(b) That the size is to be adequate for the current to be carried as set out in the
cable manufacturer's specification.
(c) That the size is sufficient to keep the voltage drop in the phase and neutral
conductor to the farthest lighting or power point, under normal full load
conditions, to within the final circuit limit specified in BS7671. Diversity will
not be allowed.
12.11
CABLE TERMINATIONS
Terminations for cables shall comprise compression type glands with armour and
bonding clamps to meet the requirements of Type E1 to BS 6121, or equivalent, and
are to be designed to secure the armour wires, to provide electrical continuity
between the armour and the threaded fixing component of the gland and to provide
watertight seals between the cable outer sheath and gland and between the inner
sheath and threaded fixing component. The glands are to project at least 10 mm
above the gland plate to avoid moisture collecting in the cable crutch.
Earth bond terminal attachments are to be provided.
Terminations for rubber insulated cables are to comprise compression type glands
where the function of the gland is to secure the outer sheath of the cable, in
accordance with the requirements of Type A2 to BS 6121 or equivalent. A
watertight seal is to be provided between the outer sheath and the gland.
Only one cable is to be terminated in each gland.
SEC 12: Lighting, Small power, Heating and Ventilation
12/8
3.12
SEALING AND DRUMMING
Immediately after the works tests, both ends of all cables shall be sealed against the
ingress of moisture, dirt and insects and the end projecting from the drum shall be
adequately protected against mechanical damage during handling and shall be fitted
with a pulling eye bonded to cores, sheath and armours.
12.13
CONDUIT
All wiring shall be installed in screwed heavy gauge welded steel conduit or heavy
gauge PVC conduit, at the discretion of the Engineer. No conduit less than 20 mm
diameter will be permitted.
Surface mounted
i.e.painted blockwork.
- steel -
switchrooms, battery rooms,
Flush mounted adecorative finish.
PVC
relay control rooms which have
-
Steel conduits shall be manufactured in accordance with BS 4568, Part 1 or
equivalent, heavy
gauge screwed and welded Class B and shall be galvanised. Conduit fittings are to
be
manufactured of good quality galvanised malleable cast iron and of small circular
pattern to BS
4568, Part 2 or equivalent, with internally tapped spouts minimum length 21 mm.
threaded to the
correct length at intersections, tees, draw throughs and stopends.
Conduit fittings of PVC shall be of the plain bore pattern suitable for a push-on
compression type joint-and shall be sealed with a hard setting vinyl cement to
prevent ingress of vermin, water, dust, etc. Inspection bends, solid or normal bends,
elbows or tees are not to be used except with the approval of the Engineer.
Conduit runs shall, wherever possible, be concealed in ceilings, voids and walls,
chases etc., and in rooms of secondary importance (with back outlet entries to
switch boxes etc. especially on fair faced brickwork) otherwise the conduits shall be
securely fixed to the surface of walls using heavy cast distance saddles. Where
plastered finishes are called for, buried conduit systems shall be provided.
Where the system of wiring is concealed, the 'loop-in' system of conduit shall be
used and the 'looping-in' boxes shall conform to BS 31, Class B3.
A separate insulated earth conductor, coloured green and yellow, shall be run in
PVC conduits and such facilities shall be provided at all terminal points.
Wherever the installation is specified as being flame-proof, the conduit runs
SEC 12: Lighting, Small power, Heating and Ventilation
12/9
entering these areas shall have a barrier box inserted in the run immediately before
the conduit passes into the flame-proof area. All conduit work inside the
flame-proof area shall be carried out with solid drawn galvanised conduit and all
conduit fittings, sockets and accessories shall be galvanised and certified suitable for
Group 1 hazard. At the completion of the wiring all machine faces on accessories
shall be thoroughly cleaned and greased, prior to the screwing or bolting of all
accessory cover plates into their final flame-proof secure position.
The ends of all steel conduits shall be reamered to remove all burrs or sharp edges
after the screw threads have been cut. All dirt, paint or oil on the screw threads, the
conduit, sockets and accessories must be removed prior to erection. All conduits
shall be swabbed through prior to installation of cables.
The ends of the conduit shall butt solidly in all couplings. Where they terminate in
fuse-switches, distribution boards, adaptable boxes or non-spouted switch boxes,
they shall be connected thereto by means of smooth bore male brass bushes,
compression washers and sockets. All exposed threads and all bends shall be
painted with an aluminium spirit paint after erection.
All conduit and accessories, after being installed, shall be examined and all parts
where the surface has been chipped or scratched shall be painted.
All conduits shall be kept 80 mm clear of water, gas and other services. Should this
prove impracticable, then they shall be properly bonded by means of pipe clamps or
other device ensuring mechanically sound, electrically continuous connection.
The method of installing PVC conduit and fittings shall conform strictly to the
manufacturer's recommendation. These recommendations shall be submitted when
seeking approval to the system proposed. In general the clauses dealing with steel
conduit shall apply.
PVC tube not exceeding 25 mm in diameter shall be bent cold by means of the
appropriate spring and the tube shall be saddled as quickly as possible after bending.
When bending larger sizes of tube, the tube must be heated in an approved manner
until it is pliable. A 90˚ bend shall have a radius of not less than five times the
outside diameter of the tube.
Joints between conduits and conduit fittings shall be watertight and shall be made
by means of a solvent adhesive as recommended by the manufacturer. Care shall be
taken to ensure that the tube is clean and free from damp and grease and in
particular dust, mould and oil.
The Contractor shall provide PVC tube ends and flexible covers to prevent ingress
of concrete grout into the tubing and boxes.
All bends are to be made on Site to suit conditions and not more than two right
angle bends will be permitted without the interposition of a draw box. No tees,
elbows, sleeves, either of inspection or solid type, will be permitted. Generally long
SEC 12: Lighting, Small power, Heating and Ventilation
12/10
straight conduit runs from point to point shall have draw boxes installed at
maximum intervals of 10 metres.
Deep boxes or extension rings on standard circular conduit boxes shall be used
where necessary in order to bring the front of each box flush with the surface of the
ceiling or wall. Where conduits are laid direct on the shuttering of the reinforced
slab construction, conduit extension rings or deep boxes shall be used to raise the
run of conduit to between the top and bottom reinforcing. Galvanised draw wires or
other approved types shall be provided where conduits are not to be wired on
completion or are to be wired by others.
All draw boxes and junction boxes shall be of ample size to permit the cables being
drawn in and out. They shall be made of malleable iron or PVC approved type and
the jointing surface machined to ensure a dust tight joint. All circular boxes shall be
provided with long spouts
internally threaded incorporating a shoulder for the proper butting of the conduit and
a solid brass earth terminal tapped and screwed into the base of the box.
All conduit boxes shall be screwed on or in walls, ceilings etc. by countersunk wood
screws of appropriate size. Holes in boxes shall be adequately countersunk to ensure
the complete recession of the fixing screws. All inspection and draw-in boxes shall
be provided with covers fixed by round head brass screws.
Where surface conduit is specified, it shall be fixed by means of distance saddles
and shall terminate in raised back pattern conduit boxes. Surface conduits shall not
be bent or set to enter accessories, and where they turn through walls back outlet
boxes shall be provided. Conduits shall be fixed at 1200 mm centres on vertical runs
and 900 mm apart on horizontal runs.
Vertical conduit runs shall have saddles at 300 mm maximum from their points of
emergence from floors or ceilings and the remaining saddles shall be fixed
consistent with the requirements of spacing and appearance. Saddles shall be fixed
on each side of every bend at 300 mm maximum from the point of intersection of
the centre line conduit.
Conduits in ceiling cavities shall be supported independent of the suspended ceiling.
Where conduits cross expansion joints, the Contractor shall allow for the installation
of expansion couplers at the positions of the expansion joint and at fight angles to it.
He shall provide a bonding earth wire between each terminal fitted in the nearest
conduit box each side of the coupler.
All flexible metallic tubing shall be galvanised watertight pattern fitted with
sweated brass adaptors. External earth conductors, wrapped around the tubing, shall
be provided.
Where conduits are laid in slab floor etc., the Contractor shall arrange for a
competent person to be in attendance whilst the concrete pouting or screeding
SEC 12: Lighting, Small power, Heating and Ventilation
12/11
operation is being carried out, in order to avoid damage being caused to the conduits
and also to ensure that the conduit work is in sound condition, properly and
efficiently maintained during this installation period.
Particular care should be taken when setting out conduit runs to outlet points where
they are to be fitted to furniture, kitchen fittings, etc. The Contractor shall ascertain
exact details of the furniture and fittings construction in order that all conduit work
shall wherever possible be concealed.
Conduits installed in chases of walls and floors shall be firmly secured by wrought
iron pipe hooks or crampets and these fixings shall in themselves be sufficient to
hold the conduits in place. Conduits installed in chases shall be painted with one
coat of bitumastic paint before erection and a further coat shall be applied to all
accessible surfaces including the hooks and the crampets after erection.
Recessed conduits buried in plaster shall permit a full 6mm. depth of cover over its
entire length.
Provision shall be made for the tapping of condensed moisture.
Care shall be taken to prevent water, dirt or rubbish entering the conduit system
during erection. Screwed metal caps or plugs shall be used for protecting open ends.
All conduit systems shall be erected completely with all conduit accessories
connected. They shall then be offered for inspection and approval by the Engineer
before any cables are installed. Conduit boxes shall be fixed to the structure of the
building independently of the conduit.
Where a conduit is exposed to different temperatures (either by surrounding air
conditions or by virtue of the surrounding medium with which it is in contact) at any
particular time, the section of the conduit at the higher temperature shall be isolated
from the section at the lower temperature by means of a conduit box filled with an
approved permanently plastic compound, after completion and testing of all wiring.
Such a condition would arise if a conduit running in a warmed building is run to
exterior points.
Where galvanised conduit is specified, all conduit, accessories, switch boxes and all
associated apparatus used in the installation must also be galvanised. Galvanised
conduit shall be used when mounted outside a building, installed in floor chases
subject to dampness or accidental flooding, or buried in the ground. Conduit
systems shall be weatherproof when erected outside a building. Exposed conduit
threads shall be given a coat of zinc rich paint.
Conduit buried in the ground shall be wrapped with PVC self-adhesive tape half
lapped. The taping shall be extended for a distance of 150 mm beyond the point
where the conduit emerges from the ground. Joints in galvanised conduit systems
shall be made watertight using lead, aluminium paint and hemp and/or gaskets. The
joints shall be partially screwed up before the paint and hemp are applied to
SEC 12: Lighting, Small power, Heating and Ventilation
12/12
maintain continuity.
All adaptable boxes shall be grey iron pattern unless otherwise specified. Where
adaptable boxes are fitted flush, the cover plates shall be heavy gauge metal with 12
mm overlap on all sides. The internal depth of a box shall be not less than 40 mm.
Covers shall be secured by a screw at each comer and by additional screws as
necessary to provide a maximum spacing of 300 mm between adjacent screws.
Fixing screws shall be brass (round or cheese head).
Covers for boxes shall be of the same material as the box. For boxes mounted in
weatherproof situations, the cover shall have a machined surface around the
perimeter mating with a similar machined surface on the box and shall be complete
with a gasket.
Every flush outlet box to which a luminaire pull cord switch or similar is to be
fitted, shall be equipped with an approved type of break joint ring.
12.14
CABLE TRUNKING
Where trunking is specified it shall be constructed of 1.65 mm minimum thickness
zinc coated mild steel or PVC and shall have a removable cover throughout its
length with centre screw latch fixings. Trunking shall be rigidly fixed and supplied
complete with purpose manufactured fittings, connectors, dividers, flanges, cable
retaining clips, racks and copper earth continuity links. As an alternative, if
approved, a proprietary brand of heavy duty plastic trunking may be acceptable.
When submitting details for approval, full installation instructions as recommended
by the manufacturer shall be included in the details.
All cables installed in trunking shall be labelled and identified in an approved
manner. Clips shall be at 600 mm centres. Vertical cable trunking shall be fitted
with cable pin racks arranged to avoid any strain on the cables.
All trunking shall be rust proofed, primed and painted and fixed at intervals not
greater than 1,000 mm.
12.15
CABLE TRAYS
Cable trays, where required as part of the Contract supply, are to be the perforated
galvanised sheet type.
Trays are to have upturned edges and be of a width suitable for the number of cables
to be supported and are to be supplied with purpose- made galvanised steel brackets
suitable for mounting from the building structure. External cable trays shall be
provided with covers.
Where site cutting of trays or support bracket steelwork is unavoidable, recutting
bare steel shall be protected with two coats of an approved zinc rich paint
SEC 12: Lighting, Small power, Heating and Ventilation
12/13
immediately after cutting.
12.16
CABLE JOINTING
The Contractor shall be responsible for the sealing and jointing of all cables
supplied and installed as part of this Section of the Contract. Straight jointing of
cables is not permitted without the written consent of the Engineer.
12.17
CONTACTORS
Contactors shall comply with BS 5424 or equivalent and shall be of the electrically
held-in types contained in heavy gauge sheet steel cases suitable for panel
mounting. Each contactor shall be continuously rated and suitable for thirty
inductive switching operations per hour.
12.18
SWITCHES AND PUSHBUTTONS
Switches shall be rated for 15 amps, shall be single pole types and be provided with
an earth terminal.
Switches shall be one way, two-way or intermediate as required and, where
mounted together, they shall be fitted in a common box.
Switches for use in areas designated for surface installation shall be
quick-make-quick-break fixed grid industrial types mounted in galvanised malleable
iron boxes with protected dolly and arranged where necessary for multigang
switching.
Switches for use in areas designated for flush installation shall be micro-break types
fixed to white plastic cover plates and mounted in galvanised steel flush type boxes.
Switch-boxes shall be galvanised and fitted with screwed stainless steel front plates
having a 6 mm overlap minimum for flush installations. They shall be suitably
barriered and labelled where two phases are connected in the same box.
Switches mounted externally shall be of weatherproof pattern to IP55 level fitted
with machined box and cover joint, brass operating handles, neoprene weathertight
seals and external fixing feet.
Where DC emergency lighting circuits are to be switched, double-pole quick make,
quick break switches with pillar type terminals and earthing straps shall be
provided.
Switches shall be mounted 1.4 m above finished floor level.
Pushbutton switches shall either be flush or surface types contained in galvanised
steel boxes and be single pole rated for 5 Amps. Pushbuttons shall be made of
non-hygroscopic material, be non-swelling and so fitted as to avoid any possibility
of sticking.
SEC 12: Lighting, Small power, Heating and Ventilation
12/14
The terminals for all switches shall be adequate to accommodate 2 conductors, each
a minimum of 1.5 mm2 in area.
12.19
LIGHTING FITTINGS
Illustrations and/or samples of all lighting fittings which the Contractor proposes to
purchase shall be submitted to the Engineer for approval before issuing any
sub-orders.
Lighting fittings for interior and exterior use are to be manufactured and tested in
accordance with the appropriate sections of BS 4533, IEC 60162 or equivalent and
together with all components are to be suitable for service and operation in the
tropical climate stated.
Each fitting is to be complete with all lampholders, control gear, internal wiring,
fused terminal block, earth terminal and reflectors or diffusers as specified. The
design of each fitting is to be such as to minimise the effect of glare and such that
the ingress of dust, flies and insects is prevented, where open type fittings are used it
is to be impossible for insects to become lodged therein.
The control gear for use with fluorescent lamps is to be quick or resonant start type
without starters. Chokes are to be impregnated and solidly filled with polyester
resin, or other approved high melting compound, are to be manufactured to restrict
the third harmonic content to less than 17% of the uncorrected current value, and are
to be silent in operation.
The built-in ballast units shall comply with IEC 60082 and shall include radio
interference suppressors and capacitors to correct the fitting power factor to a
minimum of 0.85 lagging. Control gear noise levels shall be minimal.
Fittings shall be supplied complete with closed end vitreous enameled metal
reflectors or totally enclosed opal plastic diffusers, which shall be fully
interchangeable.
Dispersive reflector fittings suitable for mercury bulb fluorescent or tungsten
filament lamps shall be of heavy gauge sheet steel finished vitreous enamel. They
shall be fitted with anti-vibrators and arranged for conduit box mounting, direct or
pendant, on galvanised ball and socket dome type lids.
Bulkhead fittings shall have cast bases tapped for conduit entry, hinged bezels, heat
resisting prismatic glasses fitted with neoprene gaskets and porcelain lampholders.
Circuit cable shall not be connected direct to bulkhead fittings but shall terminate in
a fixed base connector mounted in a conduit box adjacent to the fitting. Final
connections to each fitting shall be carried out with silicone rubber covered cable.
All bulkhead fittings shall be watertight pattern.
LED flood light fittings shall be explosion-proof, featured with high strength,impact
resistance anticorrosionwith performances of strong waterproof and dustproof ,body
material shall be aluminium alloy.
Internal connections are to comprise stranded conductors not less than 0.75 MM2
covered with heat resistant insulation to the requirements of BS 6500 or equivalent.
SEC 12: Lighting, Small power, Heating and Ventilation
12/15
12.20
All internal wiring is to be adequately cleated to the fitting casing with an approved
form of cleat. The finish of fittings for interior use is to be impervious to
deterioration by atmospheric reaction. Fittings for exterior use shall have a vitreous
enamel, natural aluminium or galvanised finish according to the manufacturer's
standard product.
Lampholders for tungsten lamps up to 150 watts shall be brass or porcelain BC type
and for higher ratings shall be ES or GES type according to size. Fittings for
housing tungsten lamps exceeding 150 watts rating are to be provided with an
approved method of dissipating heat from the lamp cap and terminal housing.
Lampholders as applicable are to be suitable for the lamp specified.
Lighting fittings are to be of the type description as generally set out in the schedule
appended to this section of the Specification. The type references used are to be
repeated in the Schedules and on the drawings.
LAMPS
The Contract includes the supply and erection of all lamps and tubes necessary to
complete the installation.
Fluorescent lamps shall be manufactured and tested in accordance with BS1853,
IEC 60081 or equivalent, shall be bi-pin types and shall have colour rendering
values of X = 0.335 and Y=0.342 (i.e., Colour 2) on the CIE chromaticity scale.
Tungsten lamps shall be manufactured and tested in accordance with BS 161 or
equivalent and shall be bayonet cap for lamps up to and including 100 watts. Lamps
rated for 150 watts and higher shall have edison screw caps. Low wattage lamps
used in exit signs and emergency lighting units may be small or miniature edison
screw.
Discharge lamps shall be manufactured and tested in accordance with BS 3677 or
equivalent. Mercury vapour lamps shall be fluorescent types having a 10% red ratio
colour correction, whenever used.
LED flood light shall be rain/fog penetrable and tested in accordance with IEC/EN
62471 or equivalent.
12.21
SOCKET OUTLETS AND FUSED SPUR OUTLETS
Each socket outlet shall comply with the requirements of the BS 1363 or equivalent
and shall be the interlocked shuttered and switched types arranged for surface or
flush mounting in single or multi- gang units as appropriate.
Each fused spur outlet shall be equipped with double pole isolator, a fuse to BS
1362 or equivalent and where required front entry for flexible connection.
Each socket outlet and fused spur outlet shall be equipped with a galvanised metal
box with earth terminal.
Each group of five socket outlets is to be provided with a matching fused plug top.
SEC 12: Lighting, Small power, Heating and Ventilation
12/16
All socket outlets for exterior use shall be galvanised and weather- proof and be
equipped with screwed dust proofed cap attached to the socket by means of a chain.
12.22
TIME SWITCHES
Time switches for use with lighting systems shall be the synchronous motor wound
types protected by a suitably rated fuse for 230 volts operation with a nine hour
reserve spring and are to be fitted with a twenty-four hour hand set dial, two "off"
and two "on" levers and manual operation pushbutton. The main contacts shall be
rated for 20 Amps on a 230 Volt 50 Hz AC supply.
Time switches shall be suitable for mounting in the distribution boards supplying
the circuits to be controlled.
12.23
POLES
Lighting poles shall be tapered, of hot dip galvanised steel with bituminous
preservative inside and outside at the base and shall be approved by the Engineer.
Each pole shall be equipped with a base section compartment of 470 mm by 150
mm to house an inspection trap, lockable door, fused cutout, cable entry and
terminations for both the incoming and outgoing power cables and secondary cables
feeding the light sources.
Poles for substation lighting shall support the floodlights at 11m above ground level
and poles for access roadway lights shall support the lanterns at 4.5m above ground
level.
The Contractor shall ensure each pole is provided with foundations suitable for the
ground conditions occurring at each Site.
12.24
INTERIOR INSTALLATIONS
Wiring for the lighting and socket outlet installations shall comprise PVC cables
drawn into conduits attached to walls, structural or roof steelwork or ceilings as
appropriate. (See Clauses12.13 & 12.14).
Surface and flush type installations are required according to the particular area as
indicated in the schedule appended to this section.
In areas where flush type installations are indicated the wiring shall be drawn into
conduits buried under wall finishes or concealed above ceilings as appropriate.
All fixings shall be of a type approved by the Engineer and all metalwork used shall
be galvanised. Fixings to structural steelwork shall be with purpose made brackets
or clamps; the drilling of structural steelwork will not be permitted.
Cleats with two screw fixings shall be used for supporting conduits at not greater
than 2m intervals.
SEC 12: Lighting, Small power, Heating and Ventilation
12/17
All switchboxes, socket outlet boxes and items of a similar type shall be fixed with
two screws or bolts.
Switches and pushbuttons for lighting circuits shall be mounted at 1400 mm above
finished floor level. Socket outlets shall be mounted 500 m above finished floor
level but those for use with workshop benches shall be mounted 150 mm clear of
the bench working surface.
Lighting fittings shall be attached to ceilings, walls, trunking or roof steelwork or
suspended therefrom as appropriate.
Where fittings are to be suspended, rod type suspension units shall be employed.
Final connections to all suspended lighting fittings shall be with heat resistant
flexible cable terminated in porcelain clad connectors in the ceiling or junction box
which shall also terminate the main circuit cable. The cable length shall be such that
the suspension unit supports the full weight of the lighting fittings.
Where recessed type lighting fittings are to be installed suspension units shall be
used to prevent the weight of the fittings being applied to the suspended ceiling. It
shall be possible to carry out maintenance from the underside of the fitting without
disturbing the false ceiling. To facilitate this need the final connection to each fitting
shall be with heat resistant flexible cable from a plug in type ceiling rose mounted
above the false ceiling.
All cables not contained within conduit for their whole route shall be terminated
with a cable gland.
Where lighting fittings are mounted direct on walls or ceilings, the main circuit
cables may be connected into the fitting terminal block. Where terminal blocks do
not exist within the lighting fitting, flexible heat resistant cable shall be used
connected to a separate junction box.
Earth continuity shall be maintained throughout the entire wiring installation with
separate insulated earth continuity conductors of adequate cross-section ultimately
connected to a common earth terminal at the respective distribution board.
Within the interior installation adequate provision shall be made for connection to
small ventilating fans, which are not energised from the central air conditioning
control and starter panel.
Each and every trunking route shall be bonded across all joints with external copper
bonding links supplied for the purpose.
12.25
EXTERIOR INSTALLATION
Exterior substation lighting fittings shall be attached to substation walls at high level
or pole mounted as appropriate. Security lighting round the perimeter wall/fence is
to be provided.
SEC 12: Lighting, Small power, Heating and Ventilation
12/18
When locating the floodlights for the switchyard lighting, the Contractor shall
ensure that all floodlights are outside safety clearance for the high voltage
switchgear at the particular location.
Cables to exterior lighting shall be laid direct in ground, laid in concrete trenches or
cleated to buildings structures as appropriate to the route requirement. The cables
shall be terminated at a cut-out located at the base of each support. Wiring between
the cut-out and the control gear or lantern shall be with multicore cable run within
poles or with cable drawn into galvanised steel conduit attached to the supporting
structure.
12.26
EMERGENCY LIGHTING
Emergency lighting shall comprise lighting fittings of the types indicated in the
schedule appended to this section of the Specification.
The system shall be so arranged that on failure of the normal a.c. supplies to the
lighting installation the emergency lighting system will automatically be switched
on. Other than those of the "on demand" type, all emergency lighting shall be
switched "off" 5 minutes after restoration of normal supplies. Each emergency
lighting unit shall have a minimum 3 hour rating.
Sufficient fittings of Type E3 shall be provided in each room to enable the rooms
and building to be evacuated safely.
In addition, in designated working areas emergency manually switched lighting, to
give not less than 30 lux, shall be provided utilising type E4 fittings. Switches shall
be labelled to the approval of the Engineer.
The security lighting scheme shall illuminate the area to 6 metres inside the
perimeter wall to the lighting level specified.
12.27
TELEPHONE SYSTEM
A complete conduit/duct system shall be provided throughout the building to enable
the telephone cables to be run to the proposed extension points. This includes
telephone wiring to operators' desks and office in the control building.
Telephone instruments, the PABX and connections to PTT exchange lines shall be
carried out by other Contractor.
12.28
SCHEDULE OF LIGHTING FITTINGS AND SOCKET OUTLETS
All lighting schemes are to utilise fittings and lamp types which are available locally
in Bangladesh to ensure that replacements are readily acceptable.
Lighting fittings described in this Schedule shall also meet the general requirements
of the Clause for Lighting Fittings of this Specification.
SEC 12: Lighting, Small power, Heating and Ventilation
12/19
TYPE F1 Shall indicate a basic channel complete with control gear and
lampholders for one fluorescent lamp, equipped with an open ended
metal reflector having upwardlight slots.
TYPE F2 Shall indicate a fitting which shall comply generally with the description
for Type Fl but be equipped for use with two lamps.
TYPE F3 Shall indicate a recessed modular fitting suitable for mounting in a
suspended ceiling and equipped with a clear prismatic controller. The
metalwork and trim are to comprise a rigid welded unit so arranged as to
be invisible when erected complete with controller. The fitting is to be
equipped with a pre-wired removable gear tray and adjusting facilities to
enable levelling relative to the ceiling to be carried out after erection.
The assembly is to be complete with control gear and lampholders for
one 1500 mm long 65 watt fluorescent lamp.
TYPE F4 Shall indicate a fitting which shall generally comply with the description
F3 but with an open type grid diffuser.
TYPE F5 Shall indicate a dust-tight, weatherproof and vapour resistant fitting,
having a grey polyester fibre glass reinforced chassis containing the
control gear and having lampholders for one 1500 fluorescent lamp. The
fitting shall be complete with a vacuum formed acrylic diffuser which is
secured to the body with injection moulded toggles and sealed with a
neoprene gasket.
TYPE F6 Shall indicate a weatherproof bulkhead fitting with a cast aluminium
base and vandal resistant diffuser equipped with control gear and
lampholders for two fluorescent lamps.
TYPE E1
Shall indicate a self-contained, self-sustained (normally off) emergency
lighting unit, complete with integral batteries and control gear, with the
words "EXIT" in white letters on red background in English and Arabic.
It shall be energised from the batteries under mains failure conditions.
The mains failure device shall be sensed by an unswitched phase
connection from the local lighting circuit.
TYPE E2 Shall indicate a self-contained, self-sustained (normally off) wall
mounted emergency lighting unit comprising a pilot light and two 100
watt spotlights complete with integral batteries and control gear. The
pilot light shall be energised under mains failure conditions with manual
"on demand" switches for the spotlights. The mains failure device shall
be sensed by an unswitched phase connection from the local lighting
circuit.
TYPE E3 Shall indicate a self-contained, self-sustained (normally off) wall or
ceiling mounted emergency lighting unit complete with integral
SEC 12: Lighting, Small power, Heating and Ventilation
12/20
batteries and control gear. The lamps shall be energised under mains
failure conditions. The mains failure device shall be sensed by an
unswitched phase connection from the local lighting circuit.
TYPE E4 Shall indicate a 110V DC wall or ceiling mounted emergency lighting
unit which shall be manually switched and be similar to type E3.
TYPE H1 Shall indicate forward throw floodlight fitting comprising a sheet steel
vitreous enamelled or spun aluminium reflector housing a 500 Watt
Halogen lamp. The fittings to be complete with wall mounting bracket.
TYPE H2 Shall indicate a semi cut-off roadway and perimeter security lantern
with housing manufactured from a one piece LM6 aluminium alloy
casting enamelled white internally and equipped with reflector bowl of
heat resisting glass, all suitable for housing the lampholder and control
gear for one 150 Watt sodium vapour lamp. The fitting to be equipped
with pole arm suitable to give an outreach of 1 metre.
TYPE S1
Shall indicate a 13 Amp single or double gang flush mounted switched
socket outlet.
TYPE S2 Shall indicate a 13 Amp single or double gang surface mounted
switched socket outlet.
TYPE S3 Shall indicate an ironclad one gang heavy duty 4 pole interlocked
switched socket outlet with scraping earth connection suitable for use on
a 400V 3 phase 4 wire 50 Hz for 125A. Each socket is to be supplied
complete with cable box with 2 glands, suitable for terminating a
PVCWPVC cable and shall be fitted with a screwed dustproof cap
attached to the top of the socket by means of a chain. Matching plugs to
be provided in each socket.
TYPES4
12.29
Shall indicate a 15 amp 3 phase 4 wire switched socket outlet with plug
flush mounted.
SCHEDULE OF LIGHTING REQUIREMENTS
12.29.1 Control Building
Location
(a)
(b)
(c)
(d)
(e)
Service
Illuminance (Lux)
Control Relay Room
Behind panels
Office
Battery Room
Toilet
Glare
Index
400
100
500
100
100
25
20
-
SEC 12: Lighting, Small power, Heating and Ventilation
12/21
(f)
Corridors, Stairs
100
20
12.29.2 Outdoor Areas
(a)
(b)
(c)
(d)
(e)
12.30
Switchyard Floodlighting
Transformer Compounds
Roadway Lighting
20
Perimeter Wall Security 10
Control Building Exterior
20
120
15
-
-
AIR CONDITIONING AND VENTILATION
12.30.1 Scope of Work
This Section of the works covers the design, supply, delivery, installation,
commissioning and setting to work of the heating and ventilating systems for the
control building.
All heating and ventilating systems shall be fully automatic in operation and shall be
capable of maintaining internal conditions within the bands of temperature and
humidity specified hereafter. the substations are normally manned and allowance
shall be made for at least four persons on site in the design.
13.30.2 Heating
Electrical heating shall be provided for each room of the building. Except for the
battery room, the heating shall comprise of 1500mm long tubular heaters with a
load of 60 watts/foot (300mm) which shall be mounted in double tier banks.
Electric heaters shall be fitted with bright plate safety guards affording full
protection to the heating tubes. The Contractor shall assess the thermal performance
of the building and ensure that the sizes of units are adequate to maintain internal
temperatures of 5° C when the external temperature is -3°C, measured 1200mm
above finished floor level out of an air stream.
The heaters in each room shall be controlled by contactors which have thermostats
connected into the coil circuit. Thermostats shall be located in each room and have
a maximum cut-off temperature of 17° C.
Each heater bank shall be equipped with a local isolator. The lower tubular heater
shall be mounted at 500mm above finished floor level.
12.30.3 Air Conditioning
The following areas shall be air conditioned.
Control/Relay room
Communication/SCADA/PLC room
SEC 12: Lighting, Small power, Heating and Ventilation
12/22
Office/record room
Air conditioning shall be provided in the form of Air Cooled Split System Air
Handling Units. The systems shall handle predominantly recirculated air with a
controlled quantity of fresh air introduced either at each unit or independently via a
separate supply and extract system. Supply air distribution ducts for the
Control/Relay room shall be located in the false ceiling serving supply diffusers.
Return (recirculated) air shall be drawn in through the front of each unit.
The cooling medium for the split System Air Handling Units shall be direct
expansion provided by air cooled refrigeration condensing units located on the roof
of the building or wall mounted on building exterior, and interconnected by
refrigerant pipe work to multi circuit direct expansion cooling coils.
Air conditioning system shall be thermostatically controlled to maintain internal
conditions under continuous operation within the limits stated. Plant shall be
arranged to facilitate maintenance and future replacement of equipment.
12.30.4 Mechanical Ventilation
Supply and extract ventilation shall be provided to serve the following areas:Switchgear room
Battery Rooms
Toilets (Extract only)
Cable basement
Supply air handling plants shall consist of a sand trap fresh air intake louvre, insect
screen, pre-filter, bag filter, electric air heater battery, fan and distribution ductwork.
The air intake shall not face the prevailing wind.
Extract ventilation shall be provided by means of wall mounting fans, roof extract
units or ducted systems with louvered discharges to atmosphere. Individual extract
fans shall be provided for Battery room and toilets.
Extract fans for battery room shall be corrosion resistant throughout, with a 4 mm
PVC lining.
12.30.5 Basis for Design
(a) External Design Conditions
The external conditions for the calculation of duties for the mechnaical services
shall be with mean monthly, maximum and minimum values as below:
Maximum ambient shade temperature
45 oC
Minimum ambient shade temperature
4 oC
Maximum daily average temperature
35 oC
SEC 12: Lighting, Small power, Heating and Ventilation
12/23
Maximum annual temperature
25 oC
Relative humidity - maximum
100%
- minimum
Solar radiation
80%
100mW/sq.m
All plant and equipment installed externally, or which can be affected by
external condition shall be capable of withstanding without damage or
deterioration the effects of solar radiation, rain, wind, dust, sand storms or
other weather phenomena prevalent in the area in which particular building is
located.
(b) Internal Design Conditions
Air conditioning systems shall be capable of maintaining internal l conditions
in all air conditioned areas within the following bands or, if necessary for the
satisfactory operation of the equipment housed, more stringent requirements:
For substations
22+4 oC DB
40 to 70% R.H.
The following air change rates/hour shall be provided in mechanically
ventilated area:
Switchgear Rooms 10
Battery Rooms
10
Toilets
12 (Extract only)
Cable basement. 6
Other general areas 4
All air conditioning and ventilating systems shall be designed for continuous
operation. Plant shall be arranged to facilitate maintenance and future replacement
of equipment.
The Contractor shall calculate heat gains and losses under the specified conditions
for each part of each building, taking into account solar radiation, thermal
transmittance through roofs, walls, floors and windows, fresh air requirements, heat
emission from installed e1ectrical equipment and lighting, personnel, infiltration
and any other sources. The Contractor shall be responsible for determining the heat
transfer coefficients for all materials used in building construction. In the event of
any change in materials. design or method of building construction, the Contractor
shall at all times be responsible for rechecking the design of all systems to ensure
that they are capable of meeting the specified design requirements
12.30.6 Air Cooled Condensing Units
The cooling medium for the air conditioning shall be direct expansion refrigeration
provided by air cooled condensing units located externally.
SEC 12: Lighting, Small power, Heating and Ventilation
12/24
The condensing units shall be of the fully packaged type requiring only site
connection of refrigeration pipe work, , isolated electrical supply and input from the
control system.
The individual item of refrigerant equipment shall be matched such that the required
performance of the evaporator is achieved concurrently with the satisfactory
operation of the compressor and adequate heat rejection at the condenser. Each
system as a whole shall maintain the correct duty at the design ambient and operate
at the maximum ambient conditions stated without exceeding the safe operational
limits of any individual item of equipment and without causing any safety device to
operate.
All electrical equipment, control, magnetic coils and solenoids shall be
manufactured specifically for operation at the electrical characteristics specified
herein and such items designed for any other characteristics shall not be used.
Air cooled condensing units and air handling units that are inter-connected on site
with refrigerant piping shall all be supplied by the same manufacturer.
The casings of the condensing unit shall be weatherproof and shall incorporate
adequate access and inspection panels secured in place by rustproof fasteners.
The whole of the casing shall be treated for corrosion and weather resistance and
ungalvanized mild steel shall not be used (even if painted).. The unit shall be
finished in not less than two coats of weather resistant finish, such as baked enamel
of a light reflective colour.
The access panels shall be adequately sized for the service and removal of all
working parts of l the unit. All panels shall be stiffened and supported to prevent
flexing and drumming.
Electrical equipment shall he contained in a fully weatherproofed enclosure with
internal division between the power connections and equipment and the control
connections and equipment.
12.30.7 Refrigeration Systems
(A) Liquid lines shall be insulated where they are in direct sunlight or where they
pass though non-air conditioned areas.
Suction lines shall be insulated over their entire length.
All insulation to refrigeration pipe work shall be flexible closed cell l foam
phenolic rubber type with a temperature range of -40°C to +105°C and having
a thermal conductivity of 0.0375 w/m °C at 2l °C and a water vapour
transmission of less than 6.0 ng/Ns.
The thickness of insulation shall be in accordance with the following tables:-
SEC 12: Lighting, Small power, Heating and Ventilation
12/25
i)
Suction Lines
Location
Insulation thickness for O.D. Pipe Sizes Range
6-10mm
12-22mm
Exposed to weather
13mm
19mm
In air conditioned spaces
9mm
19mm
In non-air conditioned spaces
9mm
9mm
9mm
9mm
ii) Liquid Lines
Exposed to weather and
in non-air conditioned spaces
(b) The refrigerant used shall conform to BS 4334 Group 1 or equivalent and shall
be non explosive, non-combustive, non-toxic and non-irritating.
Packaged air conditioning plant items requiring interconnection with
refrigeration piping on site shall be leak tested by the manufacturers and
delivered to site with a holding charge of refrigerant.
12.30.8 Console Air Conditioning Units
Console model room air conditioners shall be of the slim-line pattern and complete
with 4-way adjustable grilles, heavy gauge zinc coated stove enamelled sheet steel
casing with single or two colour decorative finish. Electrical-heaters shall not be
fitted.
The casing and position shall be such as to protrude not more than 250 mm into the
air-conditioned space and no external projection beyond the building line will be
permitted other than the fixing of the condenser cooling air grille.
The units shall be extremely quiet ill operation, the noise level not being higher than
30 dB. All sections of :he casing shall be acoustically and thermally insulated.
Compressors shall be of the fully hermetic type, fitted with resilient mountings and
complete with thermal overload protection and starting relays.
Evaporators shall be manufactured of' copper tube with copper or aluminum fins
mechanically bonded. The evaporator fan shall be of double inlet, double width type
and complete with continuously rated totally enclosed electric motor.
Filters shall be of the washable type, suitably positioned for easy access for
cleaning.
Automatic control by means of an integral thermostat shall be provided, together
with the safety control to prevent excessive cooling.
Motors shall be air cooled and units shall be complete with internally mounted
condenser cooling fans with totally enclosed motors.
SEC 12: Lighting, Small power, Heating and Ventilation
12/26
Fresh air shall be introduced separately by means of a central fresh air plant, where
these units are proposed to serve individual offices in a building.
Units shall be supplied as a whole and be suitable for easy removal and repositioning should this be desired at a later date.
12.30.9 Ductwork
All sheet metal ducting shall be manufactured and installed in accordance with the
Institution of Heating arid Ventilation Engineers Guide to Current Practice Section
B 16, the American Society of Heating, Refrigeration and Air Conditioning
Engineers, or the Heating and Ventilating Contractors Association of United
Kingdom Specification DW/142 or equivalent international standards for sheet
metal ductwork for low velocity low pressure air system with air velocity of up to
10 m/s.
Ail ductwork and fittings serving hazardous areas, such as battery rooms where
corrosive fumes are expected, shall be of rigid PVC materials.
12.30.10Condensate Drains
Provision shall be made for condensate to be passed into the rainwater drainage
system. Condensate drains must be routed directly into the drainage system or
individual soakaways. Pipes discharging onto substation or building brick paving
will not be permitted.
12.30.11 Extract Ventilation Units
This clause covers fan powered extract ventilation units for mounting in walls and
windows, on roofs and in plant rooms.
Extract units shall incorporate propeller. aerofoil, axial, centrifugal or hybrid type
fans which shall be constructed in accordance with the relevant sections of this
Specification.
Roof units shall comprise a galvanised sheet steel base suitable for use as a
weathering skirt, a mild steel fan/motor mounting frame and a spun aluminium
cowl.. The sheet steel base shall be constructed to support the fan/motor without
distortion and where the fan is belt driven shall incorporate a rigid subframe for
motor mounting. Fans shall be diaphragm mounted or fitted with a cylindrical
casing designed for removal from the unit from inside or outside the building
without disturbing the weathering skirt or cowl fixings. The cowl shall be
weatherproofed and shall be hinge mounted to provide complete access to the
fad/motor.
Lubricating points shall be extended to a convenient access point.
Stainless steel nuts, bolts and washers shall be used for all fixings exposed to the
weather.
SEC 12: Lighting, Small power, Heating and Ventilation
12/27
12.30.12 Air Filters
All filter media hall be properly bonded and protected against filter fibre or particle
migration. The direction of air flow shall be clearly marked on all filter panels and
on installation frames.
Access to filters shall be through removal panels fitted with quick release fasteners
and rubber sealing gaskets.
Each disposable panel filter system shall be provided with 4 complete spare sets for
use during the commissioning period. These sets shall be in addition to any filter
cells supplied as spares in accordance wit11 the general clauses of this
specifications.
Filter performance shall, unless otherwise noted, be taken to mean the Overall
Gravometric Efficiency against BS 6540:Part I Duct Test or equivalent.
Filter media of all types and sizes shall be supported in rigid peripheral frames with
internal or external wire support of the media to ensure that the media shall not
collapse under air flow. The holding frames shall incorporate accurately sized
channel sections to provide a good fitting for the filters.
The type of washable and/or disposal panel filters shall be subject to the Engineer's
approval.
12.30.13 Grilles and Louvres
Grilles shall be of aluminum construction and shall be fixed by means of subframe
with spring clips or screw fixings.
The corners of front flanges of grilles and subframes shall be mitred and jointed to
produce a clean unbroken appearance and visible aluminum sections shall be free
from extrusion marks.
Front flanges shall be at least 30mm wide and shall incorporate a lip of at least 4.5
mm and a felt gasket. Blades shall be fixed at even centers with intermediate
mullions giving support for blades of more than 550 mm long. Grille finish shall be
anodised natural aluminium colour except where otherwise indicated.
All grilles shall be fitted with an opened blade damper for regulation purposes and
shall be fitted with acoustically lined inlet plenums where necessary in order to
comply with the acoustic limits of this Specification.
Outdoor air louvers shall be of all extruded aluminium construction fitted with
opposed blade dampers in the connected ducting where necessary for air flow
regulation, Movable blade louvres shall not be used.
Louvers shall be weatherproof and shall incorporate an aluminium wire mesh screen
on the inside surface.
The dimensions of louvers for mounting in the building structure shall suit the
SEC 12: Lighting, Small power, Heating and Ventilation
12/28
concrete block or brick modules and shall be fixed to a hardwood frame.
12.30.14 Control Equipment
Each item of shall be provided with local isolation and/or emergency stop buttons to
facilitate maintenance, inspection and emergency operation.
The control system shall be of the electronic type, capable of providing the degree
of thermostatic control specified. The Contractor shall provide full wiring diagram
of all control circuits giving terminal connection reference.
The control system shall incorporate all necessary safety interlocks for the
successful operation of the mechanical plant and system. All of the individual
control elements shall be provided by the same manufacturer.
Temperature sensors shall be of the resistance type using nickel based elements and
shall be accurate to + 1oCover the range of 0 oC to 30 oC. The sensor resistance
shall be compatible with the measuring bridge of the matching control box.
12.30.15 Electrical Connections
All electrical power control cables and wiring associated with the air conditioning
and ventilation systems, including all connections between control panels, valves,
thermostats, sensing probes and other like items shall be supplied, installed and
connected up as part of this Contract.
The cabling and wiring system shall comply with the requirements of the relevant
clauses of this Specification and be either surface or flush installation as
appropriate.
Cables and wiring shall comprise either PVCWPVC laid in cleats or trenches, or
PVC drawn into galvanised conduits and trunking.
Final connections to electric motors and all other items of plant subject to
movement and vibration shall comprise flexible cable in flexible conduit.
12.30.16 Manufacturers
Wherever possible all air conditioning and ventilating plant shall be selected from a
single manufacturer's product range and origin. Where this is not possible, because
of practical or technical constraints. then the number of different sources of origin
shall. be kept to a minimum. Local service facilities shall be available for the
equipment proposed.
The Contractor shall provide, with his submission, illustrated technical literature
covering all plant and equipment offered.
12.30.17 Standards
All air conditioning and ventilation equipment shall conform to British Standards,
SEC 12: Lighting, Small power, Heating and Ventilation
12/29
Chartered Institution of Building Services or ASHRAE recommendations or other
recognised International Standards.
12.30.18 Approval
The Contractor shall submit to the Engineer for approval copies of all his
calculations forming the basis for the selection of all air conditioning and ventilating
plant, plant selection details and full working drawings. Such approval shall not
relieve the Contractor of his contractual responsibilities.
12.30.19 Maintenance
The Contractor shall be responsible for the maintenance of all installations covered
by this section of the Specifications for the period stated elsewhere in the
Specification.
12.31
EARTHING AND BONDING
All equipment being supplied under this Section shall be effectively bonded to
ensure earth continuity throughout the system. Continuity may be provided by
means of cable armouring but a separate earth continuity conductor shall be
included with all wiring in conduits. No reliance shall be placed on metal to metal
joints in conduits for earth continuity. The earth continuity conductors shall as far as
possible be in one continuous length to the furthest part of the installation from the
controlling switchboard. The earth conductor shall connect all metal cases housing
electrical equipment. The branches shall be connected to the main conductor by
permanently soldered on mechanically clamped joints.
12.32
CCTV Camera.
At least 6(Six) IP based CCTV Camera with complete necessary hardware &
software for video recording, monitoring and storage, switch etc. shall be supply,
install and commissionedon two AIS substation at Nawabganj and Srinagar for
security purpose. The suitable location of the camera shall be finalized during
contract execution and approval shall have to be taken from PGCB design.Data
connection for individual camera shall be through well protected fiber optic cable.
Minimum specification requirement for CCTV camera has mentioned in schedule
A of section 1 of this document(Volume 2 of 2).CCTV camera system shall have to
be integrated with substations Fiber Optic Multiplexer equipment for remote
monitoring.
12.33
TESTING AND COMMISSIONING
The Contractor shall be required to prove that the installed system meets the design
requirements and Specification to the satisfaction of the Engineer.
SEC 12: Lighting, Small power, Heating and Ventilation
12/30
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 13
FIBRE OPTIC MULTIPLEXER EQUIPMENT FOR
COMMUNICATION AND PROTECTION
SECTION13
FIBRE OPTIC MULTIPLEXER EQUIPMENT FOR
COMMUNICATION AND PROTECTION
TABLE OF CLAUSES
13.1
SCOPE ................................................................................................................ 13/3
13.2
SUMMARY OF STANDARDS ........................................................................... 13/3
13.3
ABBREVIATIONS ............................................................................................. 13/5
13.4
GENERAL REQUIREMENTS .......................................................................... 13/6
13.5
GENERAL CONDITIONS ................................................................................. 13/7
13.5.1 CHANNEL CAPACITY : DIGITAL CROSS CONNECTION ....................................................... 13/7
13.5.2 REDUNDANT CENTRALISED FUNCTIONS .......................................................................... 13/7
13.5.3 POWER SUPPLY................................................................................................................. 13/7
13.5.4 ITU COMPLIANCE............................................................................................................. 13/7
13.5.5 ELECTROMAGNETIC COMPATIBILITY AND SAFETY REGULATIONS .................................... 13/8
13.5.6 AMBIENT CONDITIONS ..................................................................................................... 13/8
13.5.7 MECHANICAL CONSTRUCTION.......................................................................................... 13/8
13.5.8 NETWORK MANAGEMENT SYSTEM ................................................................................... 13/8
13.5.9 1+1 PATH PROTECTION .................................................................................................... 13/8
13.5.10 1+1 SECTION PROTECTION ............................................................................................. 13/8
13.5.11 NETWORK TOPOLOGY ..................................................................................................... 13/9
13.5.12 SYNCHRONISATION ......................................................................................................... 13/9
13.5.13 ALARMS .......................................................................................................................... 13/9
13.5.14 TEST LOOPS .................................................................................................................... 13/9
13.5.15 MAINTENANCE FACILITIES ............................................................................................. 13/9
13.6
REQUIREMENTS FOR TRANSPORT LEVEL ............................................. 13/10
13.6.1 SDH AGGREGATE UNITS ................................................................................................ 13/10
13.6.2 HDSL AGGREGATE UNITS ............................................................................................. 13/10
13.7
TRIBUTARY UNITS ........................................................................................ 13/11
13.7.1 4-WIRE INTERFACE (VF INTERFACE) ............................................................................. 13/11
13.7.2 ANALOGUE SUBSCRIBER INTERFACE.............................................................................. 13/11
13.7.3 EXCHANGE INTERFACE................................................................................................... 13/12
13.7.4 PARTYLINE TELEPHONE SYSTEM (ENGINEERING ORDER WIRE) ................................... 13/12
13.7.5 V.24/V.28 RS232 INTERFACE ........................................................................................ 13/13
13.7.6 V.11/X.24 INTERFACE .................................................................................................... 13/13
13.7.7 V.35 INTERFACE ............................................................................................................. 13/13
13.7.8 V.36/RS 449 INTERFACE ................................................................................................ 13/13
SEC 13: Fibre Optic Multiplexer13/1
13.7.9 64KBIT/S CODIRECTIONAL INTERFACE........................................................................... 13/14
13.7.10 LAN INTERFACE........................................................................................................... 13/14
13.7.11 ALARM INTERFACE ....................................................................................................... 13/14
13.7.12 TELEPROTECTION INTERFACE ...................................................................................... 13/14
13.7.13 OPTICAL PROTECTION RELAYS INTERFACE .................................................................. 13/15
13.7.14 OPTICAL AMPLIFIER ..................................................................................................... 13/16
13.7.15 BINARY CONTACT INTERFACE ...................................................................................... 13/16
13.7.16 2MBIT/S G.703/G.704 INTERFACE ............................................................................... 13/16
13.8
OPERATIONAL TELEPHONE SYSTEM ...................................................... 13/17
APPENDIX 13.A.1 .................................................................................................................... 13/17
APPENDIX 13.A.2 .................................................................................................................... 13/20
APPENDIX 13.A.3 .................................................................................................................... 13/22
SEC 13: Fibre Optic Multiplexer13/2
SECTION 13
FIBRE OPTIC MULTIPLEXER EQUIPMENT FOR
COMMUNICATION AND PROTECTION
13.1
SCOPE
This specification describes the communication requirements for the transport of
voice, data and protection signals, including engineering, configuration, testing,
installation and commissioning.
For standardization of operation performance, facilities and spare requirements,
the Fiber Optic Multiplexer Equipment for Communication and Protection to be
supplied under this project shall comprise of equipment which can totally be
integrated into the existing Telecommunication system in PGCB Network
including the Telecommunication Network Management System.
Drawing in this Specification shows the planned arrangements of fiber optic
multiplexer equipment for communication and protection. All materials and
equipment offered shall be brand new, from the manufacturer’s normal and
standard construction, designed and manufactured according the latest
technological methods.
13.2
Summary of Standards
Any international standards referenced in the specifications and our outdated shall
be replaced with the corresponding replacement.
The Equipment shall comply with the latest ITU-T recommendations for the
plesiochronous and synchronous hierarchies.
The equipment shall be independenttype tested.
In particular the mentioned recommendations shall be covered:
13.2.1
The PDH interfaces shall conform to the following recommendations:
ITU
- ITU-T G.702: General aspects of digital transmission systems – Terminal
equipment - Digital hierarchy bit rates
- ITU-T G.703: Digital transmission systems – Terminal equipment – General
Physical/electrical characteristics of hierarchical digital interfaces
- ITU-T G.704: Digital transmission systems – Terminal equipment – General
Synchronous frame structures used at 1544, 6313, 2048, 8448 and 44 736
kbit/s hierarchical levels
- ITU-T G.706: General aspects of digital transmission systems – Terminal
equipment - Frame alignment and cyclic redundancy check (CRC) procedures
relating to basic frame structures defined in recommendation G.704
- ITU-T G.711: Pulse code modulation (PCM) of voice frequencies
- ITU-T G.712: Transmission performance characteristics of pulse code
modulation channels
SEC 13: Fibre Optic Multiplexer13/3
- ITU-T G.732: General aspects of digital transmission systems – Terminal
equipment - Characteristics of primary PCM multiplex equipment operating at
2048 kbit/s
- ITU-T G.735: Characteristics of primary multiplex equipment operating at 2048
kbit/s and offering synchronous digital access at 384 kbit/s and/or 64 kbit/s
- ITU-T G.736: General aspects of digital transmission - Characteristics of a
synchronous digital multiplex equipment operating at 2048 kbit/s
-ITU-T G.737: Characteristics of external access equipment operating at 2048
kbit/s and offering synchronous digital access at 384 kbit/s and/or 64 kbit/s
- ITU-T G.823: The control of jitter and wander within digital networks, which
are based on the 2048 kbit/s hierarchy
- ITU-T G.826: Error performance parameters and objectives for international,
constant bit rate digital paths at or above the primary rate
13.2.2
The architecture of optical SDH interfaces shall conform to the following
recommendations:
ETS/EN
- ETS 300 147: Synchronous digital hierarchy multiplexing structure
- ETS 300 417: Transmission and Multiplexing (TM); Generic requirements of
transport functionality of equipment
- ETS 300 417-1-1 / EN 300 417-1-1 V1.1.2: Generic Processes and
Performance
- ETS 300 417-2-1 / EN 300 417-2-1 V1.1.2: SDH and PDH Physical Section
Layer Functions
- ETS 300 417-3-1 / EN 300 417-3-1 V1.1.2 : STM-N Regenerator & Multiplex
Section Layer Functions
- ETS 300 417-4-1 / EN 300 417-4-1 V1.1.2 : SDH Path Layer Functions
ITU
- ITU-T G.707: Network node interface for the synchronous digital hierarchy
- ITU-T G.783: Characteristics of synchronous digital hierarchy (SDH):
equipment functional blocks
- ITU-T G.803: Architecture of transport networks based on the synchronous
digital hierarchy (SDH)
- ITU-T G.805: Generic functional architecture of transport networks
- ITU-T G.826: Error performance parameters and objectives for international,
constant bit rate digital paths at or above the primary rate
- ITU-T G.841: Types and characteristics of synchronous digital hierarchy
(SDH) network protection architectures
- ITU-T G.957: Optical interfaces for equipment and systems relating to the
synchronous digital hierarchy
- ITU-T G.958: Digital line systems based on the synchronous digital hierarchy
for use on optical fibre cables
- ITU-T M.2101.1: Performance limits for bringing into service and
maintenance of international SDH paths and multiplex section
- ITU-T T.50: International Reference Alphabet (IRA) - Information technology
7 bit coded character set for information interchange
SEC 13: Fibre Optic Multiplexer13/4
13.2.3
The synchronization and timing of optical SDH interfaces shall conform to the
following recommendations:
ETS/EN
- ETS 300 417-6-1 / EN 300 417-6-1 V1.1.2: Synchronisation Layer Functions
- ETS 300 462-1 / EN 300 462-1-1 V1.1.1: Transmission and Multiplexing
(TM); Generic requirements for synchronization networks; Part 1: Definitions
and terminology for synchronization networks
- EN 300 462-4-1 V1.1.1: Transmission and Multiplexing (TM); Generic
requirements for synchronization networks; Part 4-1: Timing characteristics of
slave clocks suitable for synchronization supply to Synchronous Digital
Hierarchy (SDH) and Plesiochronuous Digital Hierarchy (PDH) equipment
- ETS 300 462-5 / EN 300 462-5-1 V1.1.2: Transmission and Multiplexing
(TM); Generic requirements for synchronization networks; Part 5: Timing
characteristics of slave clocks suitable for operation in Synchronous Digital
Hierarchy (SDH) equipment
ITU
- ITU-T G.813: Timing characteristics of synchronous digital hierarchy (SDH)
equipment slave clocks (SEC)
13.3
Abbreviations
ADM
ALS
BIP
CAS
CAP
CRC
DTMF
EN
EOW
ETS
GPS
HDSL
IEC
ITU
IP
ISDN
MCMI
MS
NE
NMS
LAN
OS
OSPF
PDH
PPP
RS
SDH
Add-drop multiplexed
Automatic Laser Shutdown
Bit Interleaved Parity
Channel Associated Signalling
Carrier-less Amplitude and Phase
Cyclic Redundancy Check
Dual Tone Multi-Frequency
European Norm
Engineering Order Wire
European Telecommunications Standards
Global
High Density Subscriber Line
International Electrical Commission
International Telecommunication Union
Internet Protocol
Integrated Services Digital Network
Multi Coded Mark Inversion
Multiplex Section
Network Element
Network Management System
Local Area Network
Optical Section
Open Shortest Path First
Plesiochronuous Digital Hierarchy
Point-to-Point Protocol
Regenerator Section
Synchronous Digital Hierarchy
SEC 13: Fibre Optic Multiplexer13/5
SNMP
SOH
STM
TCP
TTI
VC
VF
13.4
Simple Network Management Protocol
Section Overhead
Synchronous Transport Module
Transmission Control Protocol
Trail Trace Identifier
Virtual Container
Voice Frequency
General requirements
The digital multiplex equipment shall be universal, software-controlled, and
provide various interface cards to connect tributary interfaces signals such as
voice, teleprotection and data to aggregate interfaces. On aggregate level 2Mbit/s
and 8Mbit/s electrical interfaces complying with ITU-T recommendations G.703 /
G.704 and 2Mbit/s HDSL interfaces shall be available. In addition, optical STM4 aggregate interfaces on 620Mbit/s shall be available. All modules shall form an
integrated part of a shelf.
The multiplexer shall provide means to drop and insert individual 64 kbit/s
signals and allocate them to determined time slots in the 2Mbit/s streams. Path
protection on 64 kbit/s and 2Mbit/s shall be supported.
It shall be suitable for operation in substation with harsh environment with high
electromagnetic interference, be highly reliable and provide secure
communication for real time signals such as voice, SCADA, tele protection and
status/control signals.
The equipment offered shall already be working successfully in
telecommunication networks operated by power utilities. It shall comply to the
latest ITU-T standards and be able to be interconnected with telecommunication
equipment.
Any equipment in the network shall be manageable from a control centre and
there shall be means to supervise external/existing equipment as well.
As a minimum modules for the following user signals shall be available as plugin units for the digital multiplexer:
·
·
·
·
·
·
·
·
Analogue subscriber interface: subscriber and exchange side
4-wire E&M voice interface
G.703, 64kbit/s data Interface
X.24/V.11 (RS-422), Nx 64kbit/s data interface
Alarm collection interface
Teleprotection command interface
Binary signal (status and control) interface
2Mbit/s electrical interface for unframed signals acc. to ITU-T G.703 and
framed signals acc. to G.703 and G.704.
Additionally, the equipment shall provide the following aggregate interfaces:
SEC 13: Fibre Optic Multiplexer13/6
·
·
·
·
STM-4 (620 Mbit/s) optical 1+1 interface for medium and long distances, with
automatic laser shut down.
STM-4 (620 Mbit/s) optical add-drop interface for medium and long distances,
with automatic laser shut down
STM-4 (620 Mbit/s) electrical interface
2 Mbit/s HDSL interface
The equipment shall be equipped with a ringing generator for analogue subscriber
interfaces.
13.5
General Conditions
The same equipment shall be used as a terminal, for through connections (transit,
repeater) and as add-drop multiplexer (ADM) with integrated optical line
modules.
First order multiplexing (2048 Mbit/s), second order multiplexing (8448 Mbit/s/s)
and STM-4 multiplexer shall be integrated.
Conference for voice channels and point-multipoint function for data signals shall
be possible.
The equipment shall be of fully modular design, based on a single shelf.
13.5.1 Channel capacity: Digital Cross Connection
The equipment shall be equipped with a redundant cross connection function with
decentralized cross connection functions on each board.
The cross connect capacity shall be minimum 40x2Mbit/s, or 200x64kbit/s nonblocking.
13.5.2 Redundant centralised functions
The equipment shall be equipped with redundant circuits for all centralised
functions.
13.5.3
Power Supply
The multiplex equipment shall operate at 48VDC +/- 15%. Redundant powersupply shall be supported.
13.5.4 ITU Compliance
The Equipment shall comply to the latest ITU-T recommendations for the
plesiochronous and synchronous hierarchies, such as:
G.702-704, G.706, G.711-714, G.732, G.735-737, G.742, G.826, G.823, Q.552
SEC 13: Fibre Optic Multiplexer13/7
13.5.5 Electromagnetic compatibility and safety regulations
The equipment shall comply with the EN50022, EN50082, IEC 801-2, IEC
801-6 and shall be conformant with CE.
13.5.6 Ambient Conditions
Storage and transport:
-40 ... +70°C; 98% (no condensation)
Operation:
-5 ... +45 °C, humidity of max. 95% (no condensation)
13.5.7 Mechanical construction
The equipment shall be of robust design. All tributary and aggregate units shall be
integrated in the same shelf.
All connectors shall be accessible from the front.
13.5.8 Network management system
The equipment shall be software programmable, either by a local craft terminal preferably notebook - or a centralized Network Management System (NMS).
Traffic through the multiplexer shall under no circumstances depend on Network
Management System; i.e. the multiplexer has to operate without being connected
to any management system.
The Network Management System shall be used to supervise the PDH and SDH
network.
13.5.9 1+1 Path protection
The equipment shall provide means to protect 64kBit/s channels. The protection
shall be end to end from one interface (telephone or data) to the other. It shall
switch automatically from the main channel to the standby channel. It shall be
configurable whether the system switches back to the main channel (reversible
switching) or not (non-reversible).
If a path has switched to its standby route because the main route is disturbed this
shall be indicated with an alarm.
The switching shall be done within the multiplexer without using the Network
Management System.
13.5.101+1 Section protection
The equipment shall provide means to protect 8Mbit/s and 155 Mbit/s
connections. It shall be possible to use two independent links: one as the main
and the other as the standby. The system shall automatically switch to the standby
SEC 13: Fibre Optic Multiplexer13/8
connection and generate an alarm if the main connection is disturbed.
The switching shall be done within the multiplexer without using the Network
Management System.
13.5.11
Network Topology
It shall be possible to build point to point - , linear-, ring-, T, and meshed
networks.
13.5.12 Synchronisation
The equipment shall be synchronisable with an external clock, with connected
2048 Mbit/s signals and/ or with internal oscillator. The synchronization shall be
configurable and it shall be possible to distribute the synchronization to other
equipment as well.
The system shall have means to switch to select the synchronisation source as
well as means to prevent the system from switching synchronisation loops. The
equipment shall be capable select the synchronisation source by means of the
SSM (Synchronisation Status Messaging) feature according to ITU-T G.704 or
priority based.
13.5.13 Alarms
Each module shall supervise its functions and shall have an alarm-indication LED
on its front. All alarms shall be collected by the NMS.
Each node shall be capable to collect up to 50 external alarms.
13.5.14 Test Loops
The equipment shall provide means to loop signals on 64kBit/s level as well as on
2Mbit/s level. It shall indicate an alarm if a loop is activated. It shall have the
possibility to determine the time after which an activated loop is switched back.
13.5.15 Maintenance facilities
Every Network Element shall have a built-in Signal Generator and Analyser to
analyse communication paths. It must be possible to cross connect the Generator
and Analyser to transmission channels and terminate the signal in other Network
Elements. The configuration must be possible locally with the craft access
terminal and remotely with the NMS or the craft access terminal.
It must be possible to loop-back signals locally and remotely using the craft
access terminal or the NMS.
SEC 13: Fibre Optic Multiplexer13/9
13.6
Requirements for Transport Level
13.6.1SDH Aggregate Units
The interface shall be designed for use on single mode fiber at 1310nm and
1550nm. The optical connectors shall be E2000.
The following main functions shall be supported:
Termination of the OS-, RS-, MS- and VC-4 layer
Extraction and insertion of the SOH communications information
Through connections of VC-12 and VC-3
The following maintenance functions shall be supported:
Status indications
Loops
Restart after ALS
TTI monitoring
BIP Error Insertion
The following SDH interfaces shall be available:
6 × STM 4 optical port interface
4 × STM 1optical port interface
2× STM 4 electrical port interface
2× STM 1 electrical port interface
13.6.2 HDSL Aggregate Units
2Mbit/s HDSL interface
The HDSL interface shall provide means to interconnect the multiplexer over two
pairs of copper wire up to 12km using CAP modulation (Carrier-less Amplitude
and Phase). It shall communicate either with another interface of the same type or
with a remote desktop terminal.
2Mbit/s HDSL Desktop Terminal
This Terminal shall provide a HDSL interface to transmit 2Mbit/s over two pairs
of copper over a distance up to 12 km. It shall be housed in a metallic indoor
case. The following interfaces shall be available:
- G.703, 2Mbit/s, 75 ohm
- G.703, 2Mbit/s, 120 ohm
- X.21/V11, Nx 64kBit/s (N = 1 .. 32)
- V.35, Nx 64kBit/s (N = 1 .. 32)
- V.36 / RS449, Nx64kBit/s (N = 1 .. 32)
SEC 13: Fibre Optic Multiplexer13/10
LANconnection:
10/100 BaseT Ethernet connection for e.g. router supporting LAN protocols: IP,
IPX; Routing Protocols: RIP; WAN protocols: HDLC, PPP, Frame Relay
(including RFC 1490). It shall inter-operate with Cisco, Wellfleet, 3Com etc. and
be manageable locally, remotely, and with Telnet and SNMP. Two such Desktop
Terminals shall be connectable to provide a 2Mbit/s link over two pairs of copper.
HDSL Repeater:
An HDSL repeater solution for distances longer than 12km shall be offered
including a remote powering solution.
HDSL Line Protection:
The HDSL equipment shall (where necessary) be protected against influences of
induced voltages up to 10 kV.
13.7
Tributary Units
13.7.1 4-Wire Interface (VF interface)
This interface shall provide 8 voice channels with a bandwidth of 300 Hz .. 3.4
kHz and 2 signaling channels (M => E, M’ => E’) per voice channel.
Each interface shall be configurable to operate with or without CAS. With CAS it
shall use the a and b bits for the two signaling channels.
The level shall be software adjustable within the following range:
Input: +7.5 .. -16 dBr
Output:+7.0 .. -16 dBr
Modules where each interface can be individually configured with 1+1 path
protection shall be available.
13.7.2 Analogue Subscriber Interface
An interface with at least 10 subscribers as well as high-density analogue
subscriber card with 60 subscribers shall be available. The ringing generator shall
be integrated in the subscriber module interface. The ringer frequency shall be
adjustable for 20Hz, 25Hz, and 50Hz.
The following main functions shall are supported:
Downstream signaling:
Ringing
Metering
SEC 13: Fibre Optic Multiplexer13/11
Polarity reversal
Reduced battery
No battery
Upstream signaling:
On/off-hook
Pulse and DTMF dialing
Flash impulse
Earth key
General:
Constant current line feeding
Line test
Permanent line checks
CLIP (On-hook VF transmission)
Metering after on-hook
13.7.3 Exchange Interface
This interface shall provide 12 interfaces to connect remotely connected analogue
subscribers to an exchange. It shall provide the following functions:
pulse dialing
tone dialing (DTMF)
earth key function
metering function(12 kHz or 16 kHz)
flash impulse
polarity reversal
indication of busy lines
The following parameters shall be configurable by software:
input voice level –5 .. +4 dBr
output voice level –7.5 .. –1 dBr
metering pulse enable/disable
signaling bit definition
loop back of voice to the telephone
13.7.4 Partyline Telephone System (Engineering Order Wire)
An engineering order wire (EOW) facility shall be provided at each multiplexer.
The EOW shall be configured as a party line and use inband DTMF signaling to
call another EOW-Terminal. The Terminal shall have an integrated DTMF
decoder allowing to program a subscriber call number (1..4 digits), and two group
call numbers (1..4 digits each).
13.7.5 V. 24/V.28 RS232 Interface
SEC 13: Fibre Optic Multiplexer13/12
It shall support the following bit rates:
0 .. 0.3 kbit/s transp. (V.110)
0.6 .. 38.4kbit/s synchronous / asynchronous (V.110).
Modules where each interface can be individually configured with 1+1 path
protection shall be available.
13.7.6 V.11/X.24 Interface
This interface shall comply to the ITU-T X.24 recommendation for signal
definition and to V.11 for electrical characteristics.
It shall support the following bit rates:
48, 56, Nx 64 kbit/s (N = 1 .. 30) synchronous
0.6 .. 38.4kbit/s synchronous / asynchronous (X.30)
Modules where each interface can be individually configured with 1+1 path
protection shall be available.
13.7.7 V.35 Interface
This interface shall comply with the ITU-T V.35 and V.110 recommendations.
It shall support the following bitrates:
48, 56, Nx 64kbit/s (Nx = 1 .. 30) synchronous
0.6 .. 38.4kbit/s synchronous / asynchronous
Modules where each interface can be individually configured with 1+1 path
protection shall be available.
13.7.8 V.36 / RS 449 Interface
This interface shall comply with the ITU-T V.36 and V.110 recommendations.
It shall support the following bit rates:
48, 56, Nx 64kbit/s (N = 1 .. 30) synchronous
0.6 .. 38.4kbit/s synchronous / asynchronous
Modules where each interface can be individually configured with 1+1 path
protection shall be available.
13.7.9 64 kBit/s Codirectional Interface
This interface shall comply with the ITU-T G.703 part 1.2.1 for codirectional data
transfer.
SEC 13: Fibre Optic Multiplexer13/13
A module shall have at least 8 interfaces.
Modules where each interface can be individually configured with 1+1 path
protection shall be available.
13.7.10LAN Interface
There shall be a 10/100 BaseT interface available with Router Bridge and FRAD
Function available. The following specification shall be covered:
Ethernet connection:
LAN protocols:
Routing Protocols:
WAN protocols:
10/100 BaseT
IP, IPX
static IP route, OSPF2 V2
PPP, Frame Relay (including RFC 1490)
The interface shall be manageable locally, remotely, with the management system
of the platform.
The LAN interface shall support linear-, ring- and star-configurations.
The WAN side shall support link capacities Nx64kBit/s and 2Mbit/s.
13.7.11 Alarm Interface
This interface shall provide means to collect various alarms, which will be
displayed, on the Network Management System. It shall be used to manage nonPDH equipment with the PDH Network Management System.
It shall have at least 24 binary inputs and at least 4 outputs, which can be
switched by the Network Management System.
It shall be possible to connect an input to an output so that if an alarm occurs, the
output contact will be switched.
It shall be possible to label an alarm. The label-text shall be read from the
interface module so that it can be indicated on the Network Management System
as well as on the local craft terminal.
13.7.12 Teleprotection Interface
The protection of the lines shall be arranged as detailed in Section
5.Teleprotection equipment shall be provided for permissive tripping and direct
tripping on the lines.
The permissive tripping signals are required to operate circuit breaker trip relays
in conjunction with the distance protection and directional earth fault relays.
The direct tripping signals are required to operate remote circuit breaker tripping
relays.
SEC 13: Fibre Optic Multiplexer13/14
Technical Requirements:
This interface shall provide means to transmit four bi-directional command
channels.
The signals shall be adjustable from 24 to 250VDC by means of software.
All inputs and outputs shall be isolated and with EMC immunity for harsh
environment.
Security, Dependability and Transmission speed shall be selectable and
programmable.
It shall be able to drop and insert commands, transfer commands as a transit
station, it shall be possible to have AND- and OR-connections between
commands.
The interface shall support T-nodes.
The Teleprotection interface shall provide an integrated non volatile eventrecorder which shall be synchronizable either internally or by GPS or a command
counter which counts trip commands.
The teleprotection interface shall provide means for signal delay measurement.
1+1 protection must be available; the switching shall be done within less than
10ms.
The interface shall do automatic loop test every 60s.
Under no circumstances shall the interface cause trip-commands in case of power
supply failure or when put in or out of service.
It shall be possible to synchronize all teleprotection interfaces with one GPS in
one station. The GPS time shall be distributed over the teleprotection channel.
An 8-bit command addressing shall be used to prevent tripping if the signal is
inadvertently re-routed through the telecommunication network.
13.7.13 Optical Protection Relays Interface
This interface shall have an optical port to connect protection relays for
teleprotection to the multiplexer. It shall operate on 1300nm use MCMI line
coding and be suitable for teleprotection relays.
13.7.14 Optical amplifier
In case of long distance communication, which can not be covered by standard a
optical interface, optical amplifier shall be applied.
The amplifier shall
SEC 13: Fibre Optic Multiplexer13/15
-
provide a power budget of at least 48dB
for bit rates from 8 Mbit/s up to 622 Mbit/s
on a pair of single-mode fibre
for single wavelength (single channel)
have no dispersion limits for STM-4 applications up to 250km.
13.7.15 Binary Contact Interface
This interface shall provide means to transmit binary signals.
The inputs and outputs shall be isolated.
The inputs shall be suitable for 24VDC .. 60VDC.
Outputs shall be solid state relays.
The interface shall provide a 24VDC short circuit proofed auxiliary power
supply.
It shall be able to drop and insert commands, transfer commands as a transit
station, it shall be possible to have AND- and OR-connections between
commands,.
The Teleprotection interface shall provide an integrated event recorder, which
shall be synchronizable either internally or by GPS.
13.7.16 2Mbit/s G.703 / G.704 Interface
This interface shall comply with the ITU-T G.703 and G.704 recommendations.
The interface module shall have at least four interfaces to be activated
individually. It shall be possible to have 128 interface modules a multiplexer.
In order to connect different equipment, the interfaces shall be available with the
impedance of 120 ohms and 75 ohms.
The interface shall support CRC-4 multi-frame according to ITU-T G.704
(enabled and disabled by software).
The CAS signaling according to ITU-T G.704 table 9 shall be activated
optionally.
The interface shall be able to extract the 2.048 MHz clock, which can be used to
synchronize the multiplex equipment.
The interface module shall support 2Mbit/s loop-back of the incoming signal as
well as the loop-back of the internal signals.
13.8
OPERATIONAL TELEPHONE SYSTEM
SEC 13: Fibre Optic Multiplexer13/16
There are two separate telephone systems under NLDC, that is, Operational
Telephone System (IP based) and Administrative Telephone System (Traditional
circuit switch based).
An IP Phone facility shall be provided at each new substation. The IP Phone shall
be incorporated by IP connection from upstream substation through IP network in
the Operational Telephone System which is controlled from the existing call
manager at NLDC Dhaka.
At least three telephone sets proper to the above-mentioned Administrative
Telephone System shall be provided at each new substation.
The contractor shall consult the Employer and confirm whether more additional
telephone sets/instruments for the systems need to be provided including their
types and specifications.
Appendix 13.A.1
SCHEDULE OF REQUIREMENTS FOR MULTIPLEXER
SL.NO. DESCRIPTION
1.0
GENERAL:
1.1
1.2
1.3
1.4
1.5
Type of multiplexer
Complying to ITU-T rec.
Transmission Capacity
Access capacity on 64 kbit/s
Access capacity on 2 Mbit/s
1.6
Redundant central processor
1.7
2.0
2.1
3.0
3.1
3.2
Digital cross connect function
Available AGGREGATES:
Optical aggregates (ITU-T G.957)
Available TRUNK INTERFACES:
HDB3, 2 Mbit/s interfaces per module
Complying to ITU-T rec.
UNIT
Mbit/s
channels
channels
REQUIRED
SDH: ADM
Yes
STM-4: 620
Minimum 200
Minimum 40
Shall be available
Fully non-blocking
L-1.1, L-1.2
No.
4.0
Minimum 8
G.703, transparent
G.704, selectable
No.
4 or 2
HDSL, 2Mbit/s interface: no of copper
ch
30
or 15
ch / pair of wire
wires
30 / 2 pairs
___________________________________________________
30 / 1 pair
_______________________________________________________________
15 / 1 pair
Available USER INTERFACES
4.1
Voice interfaces for trunk lines:
4.1.1
1 + 1 com path protection, available for
all
3.3
SEC 13: Fibre Optic Multiplexer13/17
yes
4.1.2
4.1.3
4.1.4
4.2
Analogue, 4wire with E&M: Input level
Output
level
Analogue, 2wire with E&M: Input level
Output
level
dBr
+7.5 .. –16
+7.0 .. –16.5
dBr
+6.5 .. –12.5
–1.0 .. -20
yes
4.2.1
Digital, 2Mbit/s CAS or PRI
Voice interfaces for remote
subscriber:
2wire, subscriber side
dBr
-5 .. +4 / -7.5 .. -1
4.2.2
2wire, PABX side
dBr
-5 .. +4 / -7.5 .. -3
4.3
4.3.1
4.3.1.1
4.3.1.2
4.3.1.3
Integrated teleprotection
Interface for Commands:
Number of independent commands
Transmission time max.
Signal voltage
No.
4.3.1.4
1 + 1 com path protection
4
6
250
yes
4.3.2
Interface(s) for Differential
Protection:
4.3.2.1
Electrical interface: G.703
4.3.2.2
4.4
Optical Interface
Data: channels per module
4.4.1
4.5
4.5.1
4.5.2
4.6
1 + 1 com path protection, available for
all
V.24/V.28 (RS-232): up to 38.4kbit/s
V.11/X.24 (RS-422): 64kbit/s
V.35: 64kbit/s
V.36 (RS-449): 64kbit/s
G.703: 64kbit/s
Ethernet:
10/100 BaseT
WAN capacity
Protocols
Integrated alarm gathering module:
Number of external alarms per module
Auxiliary power supply for ext. contacts
Network Management System
4.6.1
Type/Name of configuration tool
4.6.2
For fault / configuration management
Yes / yes
4.6.3
4.6.4
For local / remote operation
Data communication network (DCN)
Yes / yes
4.7
Ambient Conditions:
4.4.2
4.4.3
4.4.4
4.4.5
4.4.6
4.4.7
SEC 13: Fibre Optic Multiplexer13/18
ms
Vpeak
kbit/s
64
kbit/s
Minimum 64
yes
No.
No.
No.
No.
No.
No.
Mbit/s
No.
4
4
4
2
8
1
Min: 2x 2Mbit/s
Min.: IP
Min. 20
Yes
Ethernet / IP or
Ethernet / OSI
4.7.1
Storage: ETS 300 019-1-1, class 1.2
4.7.2
Transport: ETS 300 019-1-2, class 2.2
4.7.3
Operation: ETS 300 019-1-3, class 3.1E
4.8
Power Supply
4.8.1
Operation
4.8.2
Fully redundant power supply
SEC 13: Fibre Optic Multiplexer13/19
°C / % hum
-25 .. + 55 / class 1.2
°C / % hum
-25 .. + 70 / class 2.2
°C / % hum
-5 .. +45 / class 3.1E
VDC
48 / 60
(-15/+20%)
yes
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 14
POWER CABLES AND CABLE TERMINATING ACCESSORIES
SECTION14
POWER CABLES AND CABLE TERMINATING ACCESSORIES
TABLE OF CLAUSES
14.1
SCOPE ..................................................................................................................
14/3
14.2
STANDARDS ..................................................................................................... 14/3
14.3
CONDITIONS OF OPERATION....................................................................... 14/3
14.4
TYPE APPROVAL ............................................................................................. 14/4
14.5
CABLE LENGTHS............................................................................................. 14/5
14.6
CABLE DRUMS ................................................................................................. 14/5
14.7
SPARE CABLE................................................................................................... 14/5
14.8
SPECIAL TOOLS ............................................................................................... 14/6
14.9
CABLE JOINTING INSTRUCTIONS AND DRAWINGS ............................... 14/6
14.10
CABLE SPECIFICATION ................................................................................. 14/6
14.10.1 GENERAL ................................................................................................................................
14/6
14.10.2 CONDUCTORS .................................................................................................................. 14/6
14.10.3 CONDUCTOR SCREEN ...................................................................................................... 14/6
14.10.4 INSULATION............................................................................................................................
14/7
14.10.5 INSULATION SCREEN ....................................................................................................... 14/7
14.10.6 METALLIC SCREEN .......................................................................................................... 14/7
14.10.7 INTERMEDIATE LAYER .................................................................................................... 14/7
14.10.8 CORRUGATED SEAMLESS ALUMINIUM SHEATH .............................................................. 14/7
14.10.9 MDPE OUTER SHEATH ................................................................................................... 14/7
14.10.10 IDENTIFICATION OF CABLE ........................................................................................... 14/8
14.11
SEALING AND DRUMMING ........................................................................... 14/8
14.12
TERMINATING ACCESSORIES ..................................................................... 14/8
14.13
INSTALLATION OF CABLE ............................................................................ 14/9
14.13.1 CABLE TRENCHES WITH PITS, DUCTS AND DRAINS ........................................................ 14/9
14.13.2 SUPPORTS AND RACKS .................................................................................................. 14/10
14.13.3 BONDING ................................................................................................................................
14/10
14.14
TESTS ........................................................................................................................
14/10
14.14.1 TYPE TESTS ............................................................................................................................
14/10
SEC 14: Power Cables and Cable Terminating Accessories
14/1
14.14.2 ROUTINE/SAMPLE TESTS............................................................................................... 14/10
14.14.3 TESTS AT SITE ............................................................................................................... 14/10
14.15
EARTHING SYSTEM ...................................................................................... 14/11
SEC 14: Power Cables and Cable Terminating Accessories
14/2
SECTION 14
POWER CABLES AND CABLE TERMINATING ACCESSORIES
14.1
SCOPE
These clauses describe the General Technical Requirements for the 230kV,
132 kV & 33kV power cables& cable terminating accessories and installation
of cables and shall be read in conjunction with the Project Requirements,
Schedules and Drawings in the specification.
The power cables and accessories shall be suitable for connecting the
overhead transmission lines, power transformers with GIS.
The 33 kV cables and accessories shall be suitable for connecting the tertiary
side of 230/132/33kV, 225/300 MVA three phase power transformers with
33/0.4 kV earthing/auxiliary transformers.
The Contractor shall demonstrate that the cables have been designed, built and
installed in accordance with the relevant international standards and the
specification. It shall also operate and perform on a site in accordance with the
requirements of the specification and in the environment defined therein.
The design shall be proven by the submission of test certificates covering all
specified tests deemed to be pertinent to the plant and to the conditions in
which it will operate at the time of Biding.
The scope of work also includes supply and installation of cable sealing ends
at both ends including terminating insulators.
14.2
STANDARDS
The cable and accessories shall comply with this specification and the latest
version of relevant IEC, BS or approved equivalent. Any international
standards referenced in the specifications and our outdated shall be replaced
with the corresponding replacement.
14.3
CONDITIONS OF OPERATION
All cables shall be suitable for operation, at the guaranteed continuous ratings
specified, throughout all seasons of the year. The nominal system voltage to
which the cables will be connected is 230kV, 132kV & 33kV and the highest
operating voltage Um will be 245kV, 145kV & 36kV.
The maximum foreseeable three phase symmetrical fault current to which the
cables may be subjected is 280kA at 230KV, 225kA(for 1600mm2)
&140kA(1000mm2) at 132KV and 25kA at 33kV for one second.
Cable shall be designed to operate continuously at temperature of 90°C. Each
conductor and the metal sheath/screen shall be capable of carrying the
SEC 14: Power Cables and Cable Terminating Accessories
14/3
specified fault current for the specified time and its final temperature shall not
exceed 250°C. Adequate measure should be taken to protect against ingress of
moisture and water.
Short circuit earth fault rating of cable metal sheath or metallic screen for
230kV,132 kV and 33 kV cable shall be 50kA, 40kA(for 1600mm2), 25kA(for
1000mm2), and 5kAfor 1sec. respectively.
The maximum continuous current carrying capacity and maximum permissible
conductor temperature, and the factors for determining such rating and
temperature, shall be based on IEC recommendation No. 287 and subsequent
amendments, and all conditions obtaining on Site. The following conditions
for the design of the cables shall be assumed:l
l
l
Transmission capacity for 230 kV cable circuit:
Transmission capacity for 132 kV cable circuit:
Transmission capacity for 33 kV cable circuit:
500 MVA
300 MVA
120 MVA
Other conditions for cables laid in concrete ducts/tunnels/buried pipes shall be
assumed:l
l
l
Max. ambient air temperature:
Continuous conductor temperature:
Max. conductor temperature under fault:
45°C
90°C
250°C
The contractor shall confirm that the cable sizes are adequate for the required
circuit ratings based on the specified foregoing parameters, and he shall also
confirm that the cables are adequate for the short-circuit requirements
specified. The contractor will be required to produce cable design calculations
to verify that the selected cable sizes are suitable for the selected cable laying
conditions in concrete cable ducts, tunnels or buried pipes.
If the contractor considers that the conditions and the proximity to other power
cables, spacing and method of installation are likely to reduce the maximum
current carrying capacity he shall increase the cable conductor cross section
accordingly.
The conductor section of the cable circuits shall be adequate for carrying the
specified short-circuit current when operating under the specified load
conditions without deterioration of the dielectric or other component materials
of the cable.
14.4
TYPE APPROVAL
Cables and accessories shall have satisfactorily passed type approval tests in
accordance with the Specification and details of the cable designs offered
shall be given in the Schedule of Particulars and Guarantees. Type test
reports shall include cable design details and design drawings of each jointing
accessory included in the type test.
SEC 14: Power Cables and Cable Terminating Accessories
14/4
The Contractor shall certify that the cables and/or accessories offered will be
identical in all essential particulars in respect of design, materials and
workmanship with the cables and/or accessories for which type approval
certificates are offered in support of this bid.
The Contractor shall also ensure that all materials used will be subjected to
and shall have satisfactorily withstood such tests as are customary in the
manufacture of the types of cable specified.
Records of such tests shall be available for inspection, if required by the
Engineer.
14.5
CABLE LENGTHS
Cables shall be supplied in maximum drum lengths bearing in mind the
transport limitations in gaining access to the site. No drum shall contain more
than one length. Cables shall be installed in maximum possible lengths and
straight through jointing between shorter lengths will not be permitted.
The cable routes on the drawings attached to the Bidding Documents are
provided for information only, and it is Contractor’s responsibility to establish
the exact quantities of cables and accessories required to complete the whole
of the works as described in the Specification.
14.6
CABLE DRUMS
Cable drums shall be non-returnable and shall be made of steel suitably
protected against corrosion. They shall be lagged with closely fitting battens in
accordance with the relevant BS or equivalent IEC standard.
Each cable drum shall bear a distinguishing number on the outside of one
flange. Particulars of the cable, i.e. voltage, conductor size and material,
number of cores, type, length, gross and net weights shall also be clearly
shown on one flange. The direction of rolling shall be indicated by an arrow
on both flanges. The method of drum marking shall be to the Engineer's
approval.
Cable maintenance lengths and spare lengths shall be wound on to steel drums
before they are handed over to the Purchaser's stores. Particulars of the
cable(as stated above) shall be clearly marked on one flange.
14.7
SPARE CABLE
In addition to the cable maintenance lengths supplied against the Schedule of
Spares the Purchaser shall have the option to purchase from the Contractor at the
rates stated in the Schedule any spare cut lengths of cable for future maintenance
purposes.
Brass or other approved sealing caps of the correct size shall be supplied for each
SEC 14: Power Cables and Cable Terminating Accessories
14/5
end of spare cut cable lengths to enable them to be properly stored for future
maintenance purposes. The Contractor shall be responsible for the immediate
sealing of such cut lengths and the cost thereof shall be deemed to be included in
the contract price.
At least one additional cable shall be laid to future use for every six(6) cable of
two circuit for 230kV and 132kV and the terminal shall be sealed properly. The
employer will finalize the number of spare cable with length to be installed
during detail engineering.
14.8
SPECIAL TOOLS
Special tools used for the purpose of the cable installation, they shall be handed
over to the purchaser's stores after the taking over of the installation.
Price for such special tolls is to be considered as included in the price schedule.
14.9
CABLE JOINTING INSTRUCTIONS AND DRAWINGS
Copies of the instructions for the jointing of each type of cable terminating
and jointing accessories supplied shall be submitted to the Engineer for
approval before any work is commenced at site. One copy of each instruction
shall be bound into each copy of the Operating and Maintenance Instructions
to be supplied to the Engineer at the completion of the Contract for the use of
the Purchaser.
The following drawings shall be submitted by the Contractor for approval by
the Engineer. "As installed" drawings of cable routes shall be drawn to a scale
of 1/200. The route shall be dimensioned in such manner that it may be used
for pinpointing accurately the cables in the future. All drawings shall be
submitted for approval before the issue of the Taking-Over certificate.
14.10
CABLE SPECIFICATION
14.10.1
General
This Specification applies to single core cables with triple extrusion type solid
dielectric. They shall be generally manufactured in accordance with the relevant
International Electrotechnical Commission Publication (IEC) and British
Standard (BS) where applicable.
14.10.2
Conductors
Conductors shall be of stranded plain annealed copper wires to IEC or BS filled
to make the cables longitudinally watertight by extrusion during stranding. This
shall be to prevent ingress of water into the cable should the outer sheath become
damaged. The allowable operating temperature of conductor and waterproofing
shall be 90°C.
14.10.3
Conductor Screen
SEC 14: Power Cables and Cable Terminating Accessories
14/6
Semi-conductive tape for preventing ingress of semi-conductive XLPE and
gluing onto the stranded conductors temperature resistance up to 250°C. Semiconductive extruded cross-linked material to provide a smooth cylindrical
equi-potential surface to which the insulation can be intimately bonded. The
material shall be compatible in all respects with its conductor and insulation
materials.
14.10.4
Insulation
Cross-liked polyethylene (XLPE) melted together with the conductor screen
capable to operate at continuous conductor temperature of 90°C and short
circuit temperature of 250°C. Cross-linking process using curing is not
permitted, dry process shall be given.The insulation of the completed cable
shall be substantially free from voids and contaminants.
14.10.5
Insulation Screen
Semi-conductive compound of extruded layer firmly bonded to the XLPE
insulation. The conductor screen, the insulation and the insulation screen are
to be extruded in a single process to keep the interface smooth.
14.10.6
Metallic Screen
Where the cable core screens are inadequate to meet the earth fault current
specified, a metallic layer of adequate cross-sectional area shall be included in
the design applied over the screen. The metallic layer shall be Copper screen
with counter helix filled with swelling powder sheathed in accordance with latest
BS or IEC Publication.
14.10.7
Intermediate Layer
An intermediate layer of suitable compound shall be provided in between
metallic screen and aluminium sheath if necessary.
14.10.8
Corrugated Seamless Aluminium Sheath
Metallic sheath shall consist of the extruded corrugated seamless aluminum sheath.
Aluminum used for the sheath shall have the minimum purity of 99.5% and shall be of best
quality metal free from pinhole flaws and other imperfections. The minimum thickness at any
point shall not fall below 85% of the specified nominal thickness by more than 0.1 mm.
14.10.9
MDPE Outer Sheath
After applying the bitumin compound over the aluminium sheath, the extruded MDPE
outer sheath shall be applied.
The nominal thickness of outer sheath shall be not less the specified value.
The minimum thickness at any point shall not fall below 85% of the specified
SEC 14: Power Cables and Cable Terminating Accessories
14/7
nominal thickness by more than 0.1mm.
An outer graphite coating shall be applied to outer sheath as an electrode for
the voltage test on the extruded outer sheath.
14.10.10
Identification of Cable
The outer PVC sheath of all cables shall carry the following identification
marks in three meter intervals approximately.
"ELECTRIC CABLES- 132000 Volts/33000 Volts and cross section in sq.
mm.cu. PGCB, the name of the manufacture and the year of fabrication."
The letters and numerals shall comply with IEC or BS Publication.
14.11
SEALING AND DRUMMING
Immediately after the works tests, both ends of the cable shall be sealed
against the ingress of moisture, dirt and insects and the end projecting from the
drum shall be adequately protected against mechanical damage during
handling. The cable drums shall be arranged to take a round spindle and be
lagged with strong, closely fitting so as to take a round spindle and be lagged
with strong, closely fitting battens so to prevent damage to the cable. Only
steel cable drum shall be used.
The complete cable shall be rolled on steel cable drums capable of
withstanding the rough handling during transport without damage of the cable
and enabling easy and safe unrolling of the cable during erection.
Each drum shall have marked in indelible point on both flanges, the following
indications besides the shipping instructions.
-
14.12
Destination
Type of cable
Exact length
Net and gross weight
Trade mark
An arrow pointing in the direction of unrolling.
TERMINATING ACCESSORIES
Detailed drawings showing the types of cable sealing ends, terminal boxes and
glands proposed for the installation shall be submitted at the time of Bidding.
All cable sealing ends and terminal boxes shall be designed with jointing faces
below compound level which will ensure the retention of the filling medium
and/or cable compound under operating conditions and exclude the entry of
air, dust or moisture. Cable sealing ends and terminal boxes designed for use
with fluid or semi-fluid filling media shall have fanged joints, the faces of
SEC 14: Power Cables and Cable Terminating Accessories
14/8
which shall be machined.
An earthing strip shall be provided on all boxes terminating lead sheathed
cables.
The external dimensions, fixing cables and terminal arrangements for all
sealing ends and terminal boxes shall be agreed with the Engineer.
Sealing ends and terminal boxes shall be provided with all necessary fittings,
including external flexible connections as required. The design of flexible
connections shall be to approval.
Drain plugs shall be of ample size to permit the filling medium to be removed.
The contact faces of the cable sockets shall be thoroughly cleaned, the lugs
shall be placed in the most suitable positions and arranged as required to avoid
unnecessary bending of cable cores inside the box. Provision shall be made for
earthing the body of the box, and for expansion of the conductors in the box.
Provision shall also be made for the expansion of the filling medium and
arrangements made to prevent the formation of air spaces when filling.
14.13
INSTALLATION OF CABLE
14.13.1
Cable Tunnels and Trenches with Pits, Ducts and Drains
The contractor shall design and construct cable tunnels/Treches required for
connecting/Laying230kV,132 kV& 33kV power cables. Width and height of
cable tunnels/Treches shall conform to required cable spacing and working
spaces. The structure of cable tunnels is reinforced concrete and must be
designed enough bearing capacity cause by some parts of cable tunnel are
under heavy equipment.
The contractor shall design and construct all trenches required for the work.
The depth of the cable trenches shall be minimum 1.5 meter from the
Substation switchyard, finished level and the width shall conform to required
cable spacing and working spaces.
The thickness of cable tunnel or trench wall and floor shall be minimum
150mm and should be designed to withstand the subsoil water pressure.
Cables in cable tunnels or trenches shall be laid on cable supports at every ½
(half) meter interval.
Cable trenches shall be covered with concrete trench covers. Trenches will be
built with the top edge of the walls 50mm above the finished switchyard level.
The Cable tunnels and trenches shall have a suitable bed slope with sufficient
number of drainage pits so that water could be drained off naturally as well as
by artificial means.
The removable trench covers shall be of recast reinforced concrete adequately
SEC 14: Power Cables and Cable Terminating Accessories
14/9
designed to safely withstand a load of 2,500 N at the center of each cover. The
trench covers shall be of such size as to facilitate their handling by manual labor.
14.13.2
Supports and Racks
Cable laid supports and racks together with fixing clamps, bolts,nuts and
screws for outdoor installations and in outdoor concrete lined trenches shall be
of hot dip galvanized steel.
Cable support and rack designs shall be submitted for the written approval of
the Engineer before manufacturer or erection.
The single core cables shall be clamped to the racks with smooth finish split
packing pieces or cleats with bores of the correct size for the cable diameters.
The cleats shall be of Silicon aluminium, glass filled nylon or other tough nonhygroscopic or non magnetic material. Wooden cleats are prohibited.
14.13.3
Bonding
The cables shall be installed as an insulated sheath system. Single core cable
sheaths may either be solidly bonded (single bonding).
Bonding leads shall be of sufficient cross sectional area to carry the maximum
imposed short circuit current level. A schematic diagram detailing the
proposed bonding systems and stating bonding leads cross section shall be
submitted with the Bid.
14.14
TESTS
14.14.1
Type Tests
The cable shall be tested and shall satisfy the most recent relevant IEC
Publications.
The tests need not be carried out again if they can be provided by already
existing type tests reports of recognized laboratories.
If the cable is not yet type tested, the relevant tests shall be carried out.
14.14.2
Routine/Sample Tests
The cable shall be tested and shall satisfy the most recent relevant IEC
Publication.
14.14.3
Tests at site
After completion of the erection and before commissioning, each cable shall
be submitted to the following test:
SEC 14: Power Cables and Cable Terminating Accessories
14/10
a) Verification of the proper and complete erection of the cable and the
terminals.
b) Verification of the proper conductor’s of the external surface.
c) Verification of the proper earthing of the sheath.
d) Direct current voltage test no cables and cable terminals.
e) Power frequency test.
14.15
EARTHING SYSTEM
The cable sheath for single bonding of cable and cable end termination structures
shall be earthed at earthing mat by extending the earthing system.
SEC 14: Power Cables and Cable Terminating Accessories
14/11
POWER GRID COMPANY OF BANGLADESH LIMITED
BIDDING DOCUMENT
FOR
Design, supply, installation, testing and commissioning of
132/33kV Substations at Nawabganj, Srinagar, Narail,
Jhenaidaha and Magura
SECTION 15
QUALITY ASSURANCE, INSPECTION, TESTING, COMMISSIONING AND
WARRANTY
SECTION15
QUALITY ASSURANCE, INSPECTION, TESTING, COMMISSIONING AND
WARRANTY
TABLE OF CLAUSES
15.1
SCOPE OF SECTION ........................................................................................ 15/3
15.2
SUB-CONTRACTS ............................................................................................ 15/4
15.3
GUARANTEES .................................................................................................. 15/5
15.4
QUALITY AUDIT .............................................................................................. 15/5
15.5
MEASURING AND TESTING EQUIPMENTS ............................................... 15/5
15.6
INSPECTION PLAN AND PROCECURE ........................................................ 15/5
15.7
TEST CERTIFICATES ...................................................................................... 15/6
15.8
MATERIAL TESTS ............................................................................................ 15/7
15.9
GENERAL REQUIREMENT FOR TESTS AT MANUFACTURERS' WORK 15/7
15.9.1 TESTING OF PLANT ............................................................................................................ 15/7
15.9.2 REJECTION OF PLANT........................................................................................................ 15/8
15.10 SPECIFIC REQUIREMENTS FOR TESTS AT MANUFACTURERS' FACTORIES . 15/8
15.10.1 PRESSURE VESSELS ........................................................................................................ 15/8
15.10.2 RELAYS ...................................................................................................................................
15/8
15.10.3 ELECTRICAL INSTRUMENTS AND METERS ....................................................................... 15/9
15.10.4 AC SWITCHBOARDS ......................................................................................................... 15/9
15.10.5 CONTACTORS ................................................................................................................... 15/9
15.10.6 PVC CABLE ............................................................................................................................
15/9
15.10.7 CURRENT AND VOLTAGE TRANSFORMERS....................................................................... 15/9
15.10.8 SURGE ARRESTERS .......................................................................................................... 15/9
15.10.9 BATTERIES AND BATTERY CHARGERS ........................................................................... 15/10
15.10.10 CONTROL PANELS ....................................................................................................... 15/10
15.10.11 INSTRUMENTS ............................................................................................................. 15/10
15.10.12 POWER TRANSFORMERS .............................................................................................. 15/10
15.10.13 GIS EQUIPMENT ......................................................................................................... 15/13
15.10.14 FIBRE OPTIC MULTIPLEXER EQUIPMENT.................................................................... 15/17
15.10.15 TRANSDUCERS ............................................................................................................. 15/17
15.11 DISMANTLING PRIOR TO SHIPMENT...................................................................... 15/17
15.12 INSPECTION AND TESTING DURING SITE ERECTION ....................................... 15/17
SEC 15: Quality Assurance, Inspection, Testing, Commissioning and Warranty
15/1
15.12.1 GENERAL ....................................................................................................................... 15/17
15.12.2 MECHANICAL EQUIPMENT ............................................................................................ 15/18
15.12.3 ELECTRICAL EQUIPMENT .............................................................................................. 15/20
15.13 STAFFING ...................................................................................................................... 15/27
15.14 TAKING OVER ............................................................................................................... 15/28
15.15 DEFECTS AFTER TAKING OVER ............................................................................... 15/28
15.16 FINAL ACCEPTANCE CERTIFICATE ........................................................................ 15/28
SECTION 15- APPENDIX A .................................................................................................... 15/30
SECTION 15- APPENDIX B .................................................................................................... 15/31
SEC 15: Quality Assurance, Inspection, Testing, Commissioning and Warranty
15/2
SECTION 13
QUALITY ASSURANCE, INSPECTION, TESTING, COMMISSIONING AND
WARRANTY
135.1
SCOPE OF SECTION
The whole of the plant covered by this Contract shall be tested as detailed in
this specification and as per standard engineering practice, at contractor’s cost,
and will be subject to inspection and witnessing the tests by the Employer
during manufacture, erection and on completion.The inspection and
witnessing the tests at manufacturer’s works may be done by the Employer or
an Independent Inspection agency. The approval of the Employer/Engineer or
the passing of any such inspection or test will not, however, prejudice the right
of the Employer to reject the plant if it does not comply with the specification
when erected or when in service.
Within 40 days of the Letter of Acceptance for the Contract the Contractor
shall submit a quality assurance program and a work quality program for the
Engineer's approval. It shall be submitted on the Engineer's standard form, a
sample of which is included at the end of this Section.
The Contractor shall have an approved Quality Management System, which
shall cover all activities being undertaken during the design, procurement,
manufacturing, inspection, testing, packaging, shipping, storage, installation
and erection and commissioning of the Works.
After the award of Contract, the Engineer shall have the right to carry out a
review of the quality assurance procedures operated by the Contractor. The
Engineer's review may consider quality assurance in relation to the design and
manufacture of plant items, but may equally investigate the Contractor's
quality assurance procedures for the overall control of the wide range of
design activities necessary for a complex project of this type, and the
dissemination of paperwork, design drawings and data amongst the various
design and manufacturing organizations within the Contract. The Contractor
shall give all necessary help and assistance to the Engineer in carrying out
such a quality assurance review. The Contractor shall consider and discuss the
results of the review and make any reasonable improvements in his
procedures.
Before any plant is packed or dispatched from the Main or Sub-Contractors’
works, all tests called for shall have been successfully carried out in the
presence of the Engineer unless otherwise agreed.
30 days notice shall be given when the plant is ready for inspection or tests
and every facility shall be provided by the Contractor and his Sub-Contractors
to enable the Engineer and Employer to carry out the necessary inspection and
witnessing of tests.
SEC 15: Quality Assurance, Inspection, Testing, Commissioning and Warranty
15/3
In the cases where tests or inspection are specified as being carried out on only
a sample of the total quantity of items in the Works, and where one or more
items of the sample fail the test or inspection, a further batch of the items, at
least equal in quantity to the proportion originally specified, shall be tested or
inspected. This process shall continue until a sample proves completely
acceptable.
15.2
SUB-CONTRACTS
Within two months of acceptance of the Bid and in order to facilitate the
inspection of bought-out materials and plant, the Contractor shall submit to the
Engineer for approval three copies of all sub-orders placed by him as soon as
they are issued. One copy of any drawing or schedule referred to in the
sub-order shall be submitted simultaneously unless agreed otherwise with the
Engineer. Any reference to price may be deleted from the copies so submitted.
The sub-orders and drawings submitted to the Engineer shall cover all
components which are subject to electrical and mechanical pressure or stress
when the plant is in operation and also auxiliaries and spares which are to be
dispatched to Site direct from the Sub-Contractor's factory.
Sub-orders are to include a statement advising the Sub-Contractor that the
items being ordered will be subject to inspection and test by the Engineer and
Employer.
The Contractor shall advise his Sub-Contractors of all the pertinent clauses in
the Specification when ordering bought out plant, equipment or materials.
Every sub-order or sub-contract shall contain the following information:
(a)
Main Contractor's name and sub-order or sub-contract number.
(b)
Quantities and description of work.
(c)
Delivery requirements.
(d)
Delivery consignment instructions.
(e)
Details of Employer and/or main Contractor's applicable drawing or
schedule numbers.
(f)
Name of the Engineer.
(g)
A note advising that the plant or equipment which is the subject of the
order shall comply in every respect with the Engineer's, Specification and shall be
subject to inspection by the Engineer, Employer and the Contractor.
(h)
A reference, particularized in the accompanying Specification,
covering the following information:
Employer’s name
Project title
Contract No.
Engineer's reference number
Sub-Contractors shall comply with all the applicable requirements of
this Specification and the onus are upon the Contractor to ensure that
Sub-Contractors comply with these requirements.
SEC 15: Quality Assurance, Inspection, Testing, Commissioning and Warranty
15/4
For the purposes of this clause, interworks orders shall be treated as
sub-orders.
15.3
GUARANTEES
The Contractor shall state and guarantee the technical particulars listed in the
Technical Schedules and other sections as specified by the Contract for testing
procedures. These guarantees and particulars shall be binding and shall not be
departed from without the written permission of the Engineer. The Contractor
shall further guarantee that all equipment supplied complies with the Contract
Documents.
The tolerances permitted in the IEC and BS shall apply unless otherwise
stated.
15.4
QUALITY AUDIT
The Quality Program established by the Contractor shall be followed for all
inspection and testing procedures.
The Engineer and Employer may, from time to time, visit the manufacturer to
carry out a quality audit of the manufacturer's organization.
15.5
MEASURING AND TESTING EQUIPMENT
At prescribed intervals, or prior to each use, all measuring and testing
equipment used in inspection shall be calibrated and adjusted against certified
equipment having a known valid relationship to internationally recognized
standards.
The manufacturer shall prepare a calibration schedule showing equipment
type, identification number, location, frequency of checks, method of checking
and action to take when results are unsatisfactory.
15.6
INSPECTION PLAN AND PROCEDURE
The Inspection Plan, as submitted by the Contractor to the Engineer for
approval, shall cover the following:
(a)
Relevant International Standard. Foreach of the following stages of the
work, the acceptance criteria shall be stated.
(b)
The stages of inspection which shall include but not be limited to the
following:
i)
ii)
iii)
Tests to review or approve certification of material;
Review and approval of manufacturing procedures;
Witnessing tests or review and approval of certification of
SEC 15: Quality Assurance, Inspection, Testing, Commissioning and Warranty
15/5
operator's qualification to carry out the work required;
iv)
Visual and dimensional examination of components;
v)
Pressure tests on casings and vessels;
vi)
Non-destructive examination of materials in progress;
vii)
Functional tests on sub-assemblies, performance tests, type
tests on complete units;
viii) Examination of painting, packing and documentation for
shipment.
The Engineer will indicate the inspection requirements on the agreed
inspection programme in accordance with the following.
Hold point- Requires a mandatory inspection by the
Engineer.This inspection or test shall be witnessed by the
Engineer and Employer and further progress in manufacture
shall not be made until the plant is approved by the Engineer.
Witness point- Inspection or test of material may be carried out
by the Engineer and Employer at their discretion.
Document review- Certification of material and functional test
shall be approved by the Engineer before despatch from the
works.
13.7
TEST CERTIFICATES
Triplicate sets of all test records, test certificates and performance curves,
whether or not they have been witnessed by the Engineer and Employer, shall
be supplied to the Engineer for all tests carried out in accordance with the
provisions of this Contract.
Sets of all test certificates shall be endorsed with sufficient information to
identify the material or equipment to which the certificates refer, and shall
carry in the top right hand corner the following reference:
Employer's name
Project title
Contract No.
Engineer's reference number
All test documentation shall be in the English language.
13.8
MATERIAL TESTS
The Contractor shall provide test pieces as required by the Engineer to enable
him to confirm the quality of the material supplied under the Contract. Such
test pieces shall be prepared and supplied free of charge and any cost of the
tests shall be borne by the Contractor.
SEC 15: Quality Assurance, Inspection, Testing, Commissioning and Warranty
15/6
If any test piece fails to comply with the requirements of the appropriate
specifications for the material in question, the Engineer may reject the whole
of the material represented by that test piece; the Contractor's or
Sub-Contractor's designers and metallurgists will be consulted before any
material is so rejected.
If the Engineer is furnished with certified particulars of tests which have been
carried out for the Contractor by the suppliers of material, he may, at his own
discretion, dispense with the previously mentioned tests.
13.9
GENERAL REQUIREMENTS FOR TESTS AT MANUFACTURERS’
WORKS
15.9.1
Testing of Plant
Tests at manufacturers’ works shall include mechanical, electrical and
hydraulic tests to ensure that the plant being supplied complies with the
requirements of the Specification.
Works tests shall include all routine electrical, mechanical and hydraulic tests
in accordance with the relevant IEC or BS, except where departures therefrom
and modifications thereto are embodied in this Specification.
The Employer or its representative or independent inspection agency may
witness the tests. Sufficient notice (minimum of 30 working days) shall be
given to enable the necessary arrangements to be made.
If the plant, or any portion thereof, fails under test to give the required
performance, such further tests which are considered necessary by the
Engineer shall be carried out by the Contractor and the whole cost of the
repeated tests shall be borne by the Contractor. This also applies to tests
carried out at Sub-Contractors’ works.
Tests shall be conducted in accordance with the specified standards. When no
standards are specified, the test procedure shall be agreed between the
Employer and the Contractor.
Specific details of tests to be carried out at the manufacturers’ works are
defined elsewhere in this Specification.
13.9.2
Rejection of Plant
If any item fails to comply with the requirements of this Specification in any
respect whatsoever at any stage of manufacture, test, erection or on
completion at Site, the Engineer may reject the item, or defective component
thereof, whichever he considers necessary, and after adjustment or
modification as directed by the Engineer, the Contractor shall submit the item
for further inspection and/or test.
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15/7
In the event of a defect on any item being of such a nature that the
requirements of this Specification cannot be fulfilled by adjustment or
modification, such item is to be replaced by the Contractor, at his own
expense, to the entire satisfaction of the Employer.
15.10
SPECIFIC REQUIREMENTS FOR TESTS ATMANUFACTURERS’
FACTORIES
15.10.1
Pressure Vessels
(a)
(b)
(c)
15.10.2
All pressure vessels shall be designed, fabricated, inspected and tested
in accordance with an approved pressure vessel code or standard.
An approved method of radiographic or other non-destructive testing
shall be used for proving all welding, at all positions of possible high
stress concentration, such as large branch welds, and their vicinities
after all heat treatment is completed. This shall be done whatever the
program of non-destructive testing before heat treatment.
Hydrostatic test shall be conducted in accordance with BS 5500.
Relays
All relays and associated equipment shall be routine tested to prove the quality
and accuracy. Routine tests shall be in accordance with relevant IEC
Recommendations, supplemented by additional tests as are considered
necessary by the Employer. Routine test reports shall be submitted for each
relay and piece of equipment. The reports shall record all measurements taken
during the tests.
All relays shall be subjected to the appropriate routine tests as listed below, the
individual tests being as detailed in IEC 60255, IEC 61850 or as otherwise
agreed with the Employer.
(a)
(b)
(c)
(d)
(e)
15.10.3
Accuracy of calibrated pick-up and drop-off levels over the effective
range of settings
Insulation tests
Accuracy of timing elements
Correct operation of flag (or other) indicators
Mechanical requirements, integrity/safety of draw-out units, check of
contact pressure and alignment.
Electrical Instruments and Meters
One instrument and meter of each type and rating shall be subjected to the
tests as specified in IEC 60051.
15.10.4
AC Switchboards
Routine tests shall include general inspection and electrical operation tests.
SEC 15: Quality Assurance, Inspection, Testing, Commissioning and Warranty
15/8
15.10.5
Contactors
One contactor of each type and rating shall be subjected to type tests as
specified in IEC 292-1.
15.10.6
PVC Cable
Each size and rating of PVC cable shall be subjected to type tests as specified
in BS 6346:1989.
15.10.7
Current and Voltage Transformers
Routine tests to IEC 60044-1 and IEC 60044-2.
135.10.8
Surge Arresters
The following routine tests shall be carried out on all arrester units in
accordance with clause 9.1 of IEC 60099-4.
(a)
(b)
(c)
(d)
measurement of reference voltage
residual voltage test
internal partial discharge test
housing leakage test
The following acceptance tests shall be carried out on one complete arrester of
each voltage rating and/or type being supplied, all in accordance with Clause
9.2 of IEC 60099-4.
(a)
(b)
(c)
15.10.9
measurement of power frequency voltage at the reference current
lightning impulse residual voltage at nominal discharge current
internal partial discharge test
Batteries and Battery Chargers
Battery
-The Contractor shall demonstrate that the battery will perform the
duties specified.
Battery Charger-Routine tests according to IEC 60335.
DC Switchboard-Routine tests according to IEC 60439.
Complete charge and discharge tests on each of the combined batteries and
chargers shall be conducted and results recorded so as to permit verification of
the ampere-hour capacity of the battery. During these tests the Engineer shall
select at random reference cells and the voltage curves thereof shall be
checked when the battery is discharged over three and ten hour periods. The
alarm levels and the automatic voltage control feature of the charger shall be
demonstrated over the specified load range. Where load changeover facilities
are included, integrity of the changeover system without break or voltage
variations during loading of the standby or test charger shall be demonstrated.
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15/9
15.10.10
Control Panels
Routine operation tests and insulation resistance tests shall be carried out.
15.10.11
Instruments
Calibration tests shall be witnessed on all important pressure gauges and other
instruments as required by the Engineer.
15.10.12
Power Transformers
Inspection and testing during manufacture shall be in accordance with the
General Conditions of Contract and this section of the Specification.
Works tests shall include all routine electrical, mechanical and hydraulic tests
in accordance with the relevant IEC or British Standard, except where
departures therefrom and modifications thereto are embodied in this
Specification. For Plant not covered by any IEC or British Standard or
specifically mentioned in this Specification, such tests as are relevant shall be
agreed with the Engineer.
Should the Plant, or any portion thereof, fail under test to give the required
performance, further tests which are considered necessary by the Engineer
shall be carried out by the Contractor and the whole costs of the repeated tests
borne by the Contractor. This also applies to tests carried out at the
Sub-Contractors’ works.
After satisfactory completion of the witnessed tests at the Works, the Plant
shall be submitted for the Employer's approval during dismantling preparatory
to shipment. No item of Plant is to be dispatched to Site until the Employer has
given his approval in writing.
15.10.12.1
Main Transformers
Routine Tests
All transformers shall be subject to the following routine tests in accordance
with IEC 60076 and the requirements of this Specification.
i)
ii)
iii)
iv)
v)
vi)
Measurement of winding resistance on all tap positions and phases
Measurement of voltage ratio and check of phase displacement
Measurement of short-circuit impedance and load loss
Measurement of no load loss and current
Tests on on-load tap-changers
Dielectric Routine Tests:
The test shall be carried out in accordance with IEC 60073-3.
SEC 15: Quality Assurance, Inspection, Testing, Commissioning and Warranty
15/10
Type Tests
i)
Temperature rise test:
The test shall be in accordance with IEC 60076-2, and shall be carried
out on one transformer of each size and type. Temperature-rise tests
shall be conducted on the tapping corresponding to the maximum
losses.
ii)
Noise level tests:
A noise level test to IEC 60076-10 shall be carried out on one
transformer of each type.
Special Tests
i)
15.10.12.2
Measurement of zero-sequence impedance in three phase transformers:
The test shall be in accordance with IEC 60076-1 Clause 10.7 and shall
be carried out on one transformer of each type.
Voltage Control Equipment
Routine Tests
Each finished tap changer shall be subjected to the routine tests specified in
IEC 60214 but in addition the mechanical test shall be carried out at rated
voltage and no load.
Type Tests
Shall be carried out entirely in accordance with IEC 60214 except that
evidence of the service duty type test shall be in excess of 100,000 operations.
15.10.12.3
Magnetic Circuit
Routine Tests
Each core completely assembled shall be tested for one minute at 2,000V AC
between core bolts, side plates, structural steelwork and core at the core and
coil stage. After the transformer is tanked and completely assembled, a further
test shall be applied between the core and the earthed structural steelwork to
prove that the core is earthed through the removable link, at one point only.
15.10.12.4
Outdoor Bushing Assemblies with Porcelain Insulators
Complete bushings tested in accordance with IEC 60137
Routine Tests
To include:
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15/11
i)
ii)
iii)
iv)
15.10.12.5
Oil leakage test
50Hz dry withstand test
Power factor/voltage test
Partial discharge test on all bushings of which the major insulation is
either oil impregnated paper or resin impregnated paper.
Tanks
Routine Tests
Oil Leakage:
All tanks, conservators and oil filled compartments, which are subjected in
service or during maintenance to oil pressure, shall withstand without leakage
a hydraulic pressure test equal to 69kN/m2 or the normal pressure plus
34kN/m2, whichever is the greater, for 24 hours during which time no leakage
or oil ingress into normally oil free spaces shall occur.
15.10.12.6
Cooling Plant
Routine Tests
(a)
(b)
15.10.12.7
Coolers: Pressure test to be as specified above.
Motors and Control Gear: To the requirements as specified.
Gas and Oil - Actuated Relays
Routine Tests
(a)
(b)
(c)
(d)
(e)
15.10.12.8
Oil Leakage:
When subject to an internal oil pressure of 207kN/m2 for fifteen
minutes.
Gas Collection
Oil Surge
Performance test under service conditions
Voltage: 2kV for one minute between electrical circuits and casing.
Galvanizing
Routine Tests
To the requirements of BS 443 or BS 729 whichever is applicable.
15.10.13
GIS Equipment.:( Not Applicable )
Clause reference of type tests and routine tests are listed below. Any other
tests
specified by the referred standard (current and future issues) but not
listed
shall be applicable as well.
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15/12
Type tests shall have been carried out on the switchgear components in
accordance with the relevant IEC and BS Standards. Limiting values obtained
during Type Test shall form basis for Factory Acceptance Tests. The limiting
values shall be highlighted in the Routine Test Reports/Witness Tests.
Routine Tests
(a) One Complete Bay
IEC 62271-203 clause (for 132kV and 230kV GIS)
7.1 .1
7.1.2
7.2
7.3
7.4
7.101
7.102
7.103
7.104
Power-frequency voltage tests on the main circuit
Partial discharge measurement
Tests on auxiliary and control circuits
Measurement of the resistance of the main circuit
Tightness test
Pressure tests of enclosures
Mechanical operation tests
Tests of auxiliary circuits, equipment and interlocks in the
control mechanism
Pressure test on partitions
IEC 62271-200 clause (for 33kV GIS)
7.1
7.2
7.3
7.4
7.102
7.103
7.104
Dielectric test on the main circuit
Tests on auxiliary and control circuits
Measurement of the resistance of the main circuit
Tightness test
Mechanical operation tests
Pressure tests of gas-filled compartments
Test of auxiliary electrical, pneumatic and hydraulic devices
(b) Circuit Breaker
IEC 62271-100 Clause
7.1
7.2
7.3
7.4
7.5
7.101
Dielectric tests on the main circuit
Tests on auxiliary and control circuits
Measurement of the resistance of the main circuit
Tightness test
Design and visual checks
Mechanical operation tests (including resistance and current
measurementsof closing and trip coils and checking
anti-pumping function)
(c) Disconnector & Earth Switch
IEC 62271-102 Clause
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15/13
7.1
7.2
7.3
7.101
Dielectric tests on the maincircuit
Dielectric tests on auxiliary and control circuits
Measurement of the resistance of the main circuit
Mechanical operation tests (including verification of early
make/late break feature of disconnector auxiliary contacts as
applicable)
(d) Current Transformers IEC 60044-1, BS 3939
Routine Tests to all current transformers will be done as per specified
standards. Additional Tests required by PGCB.
Measurement of Secondary windingresistance
Measurement of magnetizing current characteristics of all CTs
Determination of Turns ratio Error for class X CTs
Verification of knee-point voltage for Class X CTs
(e) Voltage Transformers IEC 60044-2
Routine Tests applicable to voltage Transformers as per specified
standards.
(f) Surge Arresters
Routine Tests as per specified in Clause 15.10.8 in this Section.
(g) Insulators
Routine tests to
IEC 60137 for bushings
IEC 60168 and 60273 for high voltage post insulators
IEC 60383 and 60305 for cap and pin string insulators
The performance of the components of the switchgear shall be
substantiated by test data relevant to the particular designs offered.
Evidence of type tests shall be submitted with-the Bid.
Evidence of Type Tests should be provided, including the hydraulic
system, for ambient temperature of 45°C and 100% humidity.
No additional costs will be allowed for type testing to meet specified
requirements and should deficiencies in existing type test evidence occur
then the cost of such additional or repeat tests as may be required by
PGCB shall be deemed to be included in the Contract Price.
The Bidder will be deemed to have included in his price the operation test
at high temperatures in accordance with IEC 62271-203.
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15/14
(h) Local Control Cubicle
Major components of LCCs are to be tested and calibrated. Functional
testof LCCs are to be carried out in the factory during factory acceptance
test.
Type Tests
(a) One Complete Bay
IEC 62271-203 Clause (for 132kV and 230kV GIS)
6.2
6.4
6.5
6.6
6.7
6.8
6.104
6.105
6.106
Dielectric tests
Measurement of the resistance of circuits
Temperature-rise tests
Short-time and peak withstand current tests
Verification of the protection
Gas tightness tests
Pressure test on partitions
Test under conditions of arcing due to an internal fault
Insulator tests
IEC 62271-200 Clause (for 33kV GIS)
6.2
6.4
6.5
6.6
6.7
6.8
6.103
Dielectric tests
Measurement of the resistance of circuits
Temperature-rise tests
Short-time and peak withstand current tests
Verification of the protection
Tightness tests
Pressure withstand test for gas-filled compartments
(b) Circuit Breaker
IEC 62271-100 Clause
6.2
6.4
6.5
6.6
6.101
6.102
6.103
6.104
6.105
6.106
6.108
6.109
6.110
Dielectric tests
Measurement of the resistance of circuits
Temperature-rise tests
Short-time and peak withstand current tests
Mechanical and environment al tests
Miscellaneous provisions for making and breaking tests
Test circuits for short circuit making and breaking tests
Short-circuit test quantities
Short-circuit test procedure
Basic short–circuit test-duties
Single-phase and double-earth fault tests
Short-line fault tests
Out-of-phase making and breaking tests
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15/15
6.111
Capacitive current switching tests
(c) Disconnector& Earth Switch
IEC 62271-102 Clause
6.2
6.4
6.5
6.6
6.101
6.102
6.104
6.106
6.107
Dielectric tests
Measurement of the resistance of circuits
Temperature-rise tests
Short-time and peak withstand current tests
Tests to prove the short-circuit making performance of earthing
switches
Operating and mechanical endurance tests
Operation at the temperature limits
Bus-transfer current switching tests
Induced current switching tests
(d) Current Transformers IEC 60044-1, BS 3939
Type tests for Measuring Current Transformers & Protective Current
transformers shall be done as per specified standards.
(e) Voltage Transformers IEC 60044-2
Type Tests for all Voltage transformers shall be done as per specified
standards.
(f) Surge Arresters IEC 60099-4
Type Tests shall be done as per specified standards.
15.10.14
Fiber Optic Multiplexer Equipment
Works tests shall be in accordance with the IEC standard.
15.10.15
Transducers
Transducers shall be tested in accordance with IEC 60688.
15.11
DISMANTLING PRIOR TO SHIPMENT
After the satisfactory completion of all tests at the factory, the plant shall be
submitted for the Engineer's approval during dismantling preparatory to
shipping. No item of plant shall be dispatched to site until the Engineer has
given approval in writing.
15.12
INSPECTION AND TESTING DURING SITE ERECTION
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15/16
15.12.1
General
The Contractor shall be responsible for the submission to the Engineer of all
plant supplied under the Contract for inspection and testing during site
erection, to ensure correct erection and compliance with the Specification.
During the course of erection, the Contractor shall provide access as required
by the Engineer for inspecting the progress of the works and checking its
accuracy to any extent that may be required.
The Contractor shall provide, at his own cost, all labour, materials, stores, and
apparatus as may be requisite and as may be reasonably demanded to carry out
all tests during erection, whether or not the tests are specifically referred to in
this specification.
Tests on completion of erection shall be carried out by the Contractor in
accordance with the General Conditions of Contract. The Contractor shall
provide all necessary test equipment to carry out the site tests, but where
required in the Schedule of Prices, shall include the cost of the equipment so
that the Employer may have the option to buy the equipment on completion of
the Contract.
The Contractor shall submit a written programme of tests and checks
according to this Clause for the approval of the Engineer.
A brief description of all tests and testing procedures shall be provided before
tests commence and the method of testing, unless otherwise specified, shall be
agreed with the Engineer.
The Contractor shall provide experienced test personnel and testing shall be
carried out during normal working hours as far as is practicable. Tests which
involve existing apparatus and outages may be carried out outside normal
working hours. The Contractor shall give sufficient notice to allow for the
necessary outage arrangements to be made in conformity with the testing
program
The Contractor shall advise the Engineer in writing, at the time of
commencement of site erection, of the site supplies which will be required for
the operation of the test equipment, to enable the Engineer to arrange
accordingly or to agree alternative arrangements should this be necessary.
The Contractor shall record the results of the tests clearly, on an approved
form and with clear reference to the equipment and items to which they refer,
so that the record can be used as the basis for maintenance tests during the
working life of the equipment. The required number of site test result records
shall be provided by the Contractor to the Engineer as soon as possible after
completion of the tests.
No tests as agreed under the program of tests shall be waived except upon the
SEC 15: Quality Assurance, Inspection, Testing, Commissioning and Warranty
15/17
instruction or agreement of the Engineer in writing.
The Contractor's test equipment shall be of satisfactory quality and condition
and, where necessary, shall be appropriately calibrated by an approved
authority at the Contractor's expense. Details of the test equipment and
instruments used shall be noted in the test sheets in cases where the instrument
or equipment characteristics can have a bearing on the test results.
The testing requirements detailed under this Specification may be subject to
some variation upon the instruction or agreement of the Engineer where
necessitated by changed conditions at Site or by differing design, manufacture,
or construction techniques.
The Bidder is required to submit proposals for site dielectric tests and to
include in his price the costs of such tests and of such equipment as deemed
necessary.
15.12.2
Mechanical Equipment
The extent of testing during erection shall include, but not be limited to, the
following:
(a)
Checking the accuracy and alignment of plant erected. The
accuracy shall comply with the relevant standards, the specification or
the plant manufacturer's requirements as may be applicable or, where
no requirements exist, to a standard to be agreed between the Engineer
and the Contractor.
(b)
Checking the alignment of rotating equipment to the
manufacturer's requirements.
(c)
Non-destructive testing of site welds as required by the relevant
standard and as detailed in this specification.
(d)
Hydrostatic testing of pipe work systems at a pressure of
1.5 times the design pressure but not less that 4.5 bar for a period of
2 hours, or at such other conditions as may be required by the pipe
work design code.
Air piping shall be subjected to an air pressure test rather than a
hydrostatic test.
(e)
Site fabricated tanks and vessels shall be subjected to
hydrostatic tests in accordance with the relevant standards.
(f)
Hydrostatic tests shall be carried out on steam generating units
in accordance with the boiler design code.
After the hydrostatic test is carried out, the complete assembly shall be
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15/18
drained and any non-drainable sections shall be injected with an
oxygen-absorbent chemical and elements plugged.
(g)
Pressure vessels and other parts, including pipe work, that are
made up on site and are subject to pressure or vacuum under normal or
abnormal working conditions, shall be subjected to a site hydraulic test
at approved pressures and for approved periods in accordance with the
relevant standard. Where no appropriate standard exists the hydraulic
test pressure shall not be less than 1.5 times design pressure or at such
pressure to be agreed by the Engineer.
Should, in the opinion of the Contractor and with the agreement of the
Engineer, an hydraulic test be impracticable due to excessive loading
on foundations other than steel, an air pressure test may be employed in
accordance with requirements set out in BS 5500.
Vacuum tests shall be carried out at the maximum test vacuum
obtainable and the condition maintained for a period of two hours with
the system isolated. The Contractor shall state in the Schedule of
Guarantees the fall in vacuum anticipated during this period but the rate
of fall shall not exceed that which would occur due to the designed air
leakage rate being attained.
(h)
Calibration checks on all instrumentation.
(i)
Tests to demonstrate the correct functioning of the
control loops, protective devices, interlocks and alarms.
(j)
Flushing out of all pipe work systems which have not
been fully cleaned and sealed before shipping to site.
(k)
Other tests as specified which have not been previously conducted.
15.12.3
Electrical Equipment
15.12.3.1
General
A general check of all the main switchgear and ancillary equipment shall be
made and shall include a check of the completeness, correctness and condition
of earth connections, labeling, arcing ring and horn gaps, clearances, painted
surfaces, cables, wiring, pipe work, valves, blanking plates and all other
auxiliary and ancillary items. Checks shall be made for oil and gas leaks and
that insulators are clean and free from external damage. A check shall be
made that loose items which are to be handed over to the Employer e.g.
blanking plates, tools, spares, are in order and are correctly stored or handed
over.
The following general tests are to be carried out on electrical equipment after
erection at site:-
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15/19
(a)
Routine high voltage tests to the appropriate IEC Standard. Where no
relevant standard exists, tests shall be agreed with the Engineer.
Insulation resistance tests on all electrical equipment.
Continuity and conductivity resistance tests.
Test operation of alarm and tripping, devices to local and remote.
Rotational tests on all motors.
Polarity tests on CTs and VTs.
Oil tests.
Grounding system and electrode tests.
Ratio, Vector Grouping and magnetizing current tests on each
transformer.
Calibration of winding and oil temperature devices.
Vector group and phasing tests on VT circuits.
Magnetization current/voltage tests and winding resistance tests on all
current transformers.
Primary and secondary injection tests on relays, protection devices and
equipment.
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
15.12.3.2
GIS Equipment
(a) General check up as per manufactures drawings and instructions
-
Visual checking
Tightness checks of nuts and bolts
All piping and junction checks
Tightening of all terminal block connection.
Painting and corrosion protection.
Cleanliness.
(b) Generalwiring checking
(c) Insulation checking of the auxiliary circuit and the control circuit
(d) Heating and lighting circuit checking
(e) SF6 gas purity check
(f) SF6 gas dew point check
(g) SF6 gas leakage test check
SF6 gas leakage is to be checked by leak detector and gas pressure are to be
monitored for at least 7 detector and gas pressure are to be monitored for at least 7
days.
(h) SF6 gas density monitors calibration checking
(i) SF6 gas density monitors contact setting checking
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15/20
(j) Hydraulic drive unit operational check:-
Pump motor operation check.
Hydraulic drive unit gauge check.
Oil pressure loss check.
Pump motor running time check.
Accumulator pre-pressure check.
Accumulator loss of pressure alarm and lock out check.
(k) On an increasing pressure measurements on:-
Reset of the opening lockout.
Reset of the closing lockout.
Disappearance of the low pressure alarm.
Cut-off of the pumping device.
Opening of the safety valve. contd.
(l) On a dropping pressure measurement on:-
Closing of the safety valve.
Starting of the pumping device.
Appearance of the low pressure alarm..
Closing lockout.
Opening lockout -1
Opening lockout -2.
(m) Circuit breaker test:-
CB opening and closing time.
Closing at lock out pressure
Opening at a lock out pressure.
Anti pumping device operational check.
Closing coil resistance and tripping coil resistance.
Measurement of current of closing coil and trip coils.
(n) Motor operation and timing tests on disconnector and earth switch
Verification of early make/late break feature of disconnector auxiliary
contacts as applicable
(o) Spring motor charging time
(p) Measurement of the resistance of the main circuit
(q) Operational test(local, remote, supervisory)
(r) Alarm annunciation (local, remote, supervisory)
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15/21
(s) Synchronization checking
(t) Surge arrester test
It is to be tested at rated voltage and leakage current is to be recorded
(surge arrester leakage current guaranteed value is to be supplied from the
manufacturer).
(u) Interlock check
(v) Annunciation check
(w) Record pressure gauge and counter readings before commissioning
(x) CT/VT/Relays & Meters
Any additional tests recommended by the manufacturer shall be added to
the above list. Equipment not covered by the above site test list shall be
tested based on standard practice.
15.12.3.3
Earthing System
Tests shall be made on the effectiveness of the bonding and earthing which
will include conductivity tests on selected joints, on the main earthing system,
and at the connections to equipment and structures. Checks shall also be made
on precautions taken to avoid corrosion attack on the earthing system.
The earth resistance shall be measured during the installation and on
completion as follows:
(a)
(b)
(c)
(d)
of each earth rod after driving
of the earth grid after completion and backfilling of the trenches
of each group of earth rods or earth point after completion of the
connection from the test link terminal
of the completed installation without any connections outside the
substation
The tests shall be carried out by a method and with equipment approved by the
Engineer. All tests are to be witnessed and the equipment and method used
recorded with the test results.
The Contractor may also be called upon to provide assistance in the
measurement of earth resistance after earth connections to the system have
been completed.
15.12.3.4
Control Relays and Metering Panels, Instruments and Protective Devices
(a)Wiring
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After complete erection and cabling, all circuits shall be subjected to the
high voltage test specified in the relevant IEC or approved standard.
The insulation resistance of all circuits shall be measured before and after
any high voltage tests.
For AC secondary injection tests a substantially sinusoidal test supply shall
be used.
The operating and resetting level (current and/or voltage) and timing of all
relays shall be measured over an agreed range of settings for all relays.
For directional relays phase-shifting transformers shall be used to
determine the maximum torque angle and the boundaries of
operation/restraint.
Other relays shall be fully tested in accordance with the manufacturer's
recommendations.
All DC elements of protection relays shall be tested for operation at 70%
rated voltage.
All DC supplies shall be checked for severity of current inrush when
energized by switching on or inserting fuses or links.
(b)Mechanical Inspection
All panel equipment is to be examined to ensure that it is in proper working
condition and correctly adjusted, correctly labelled and that cases, covers,
glass and gaskets are in good order and properly fitting.
(c)General
Sufficient tests shall be performed on the relays and protection schemes to:
i) establish that the equipment has not suffered damage during transit.
ii) establish that the correct equipment has been supplied and installed.
iii) confirm that the various items of equipment have been correctly
interconnected.
iv) confirm performance of schemes designed on the bases of calculation
e.g. differential protection.
v) to provide a set of figures for comparison with future maintenance
values allowing the condition of the equipment to be determined.
(d)Secondary Injection
Secondary injection shall be carried out on all AC relays, using voltage and
current of sinusoidal wave form and rated power frequency to confirm
satisfactory operation and range adjustment.
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15/23
The polar characteristic of all distance protections shall be recorded at a
minimum of 30 degree intervals.
For circulating current protection employing high impedance voltage
operated relays, the points of injection for relay voltage setting tests shall be
across the relay and stabilizing resistance.
The fault setting for the type of protection is to be established by secondary
injection, where it is impracticable to ascertain this value by primary
injection. Injection is to be made across the appropriate relay bus wires
with all associated relays, setting resistors, and CT's connected.
(e)Primary Injection
All current operated relays shall be tested by injection of primary current to
record the actual relay setting and as a final proof of the integrity of all
secondary connections.
The stability of all differential schemes shall be checked by injection of
primary current.
Primary current injection tests are to be carried out by the