Instruction Manual - Type 38-3AH3 vacuum circuit breaker (E50001-F710-A238-V3

Instruction Manual - Type 38-3AH3 vacuum circuit breaker (E50001-F710-A238-V3
www.usa.siemens.com/mvswitchgear
Instruction manual
Type 38-3AH3 38 kV vacuum circuit breaker
Installation operation maintenance E50001-F710-A238-V3-4A00
Answers for infrastructure and cities.
Hazardous voltages and high-speed moving parts.
Will cause death, serious injury or property damage.
Always de-energize and ground the equipment before maintenance. Read
and understand this instruction manual before using equipment.
Maintenance should be performed only by qualified personnel. The use of
unauthorized parts in the repair of the equipment or tampering by
unqualified personnel will result in dangerous conditions which will cause
death, severe injury or equipment damage. Follow all safety instructions
contained herein.
Important
The information contained herein is general
in nature and not intended for specific
application purposes. It does not relieve the
user of responsibility to use sound practices
in application, installation, operation and
maintenance of the equipment purchased.
Siemens reserves the right to make changes
in the specifications shown herein or to
make improvements at any time without
notice or obligation. Should a conflict arise
between the general information contained
in this publication and the contents of
drawings or supplementary material or
both, the latter shall take precedence.
Qualified person
For the purpose of this instruction manual a
qualified person is one who is familiar with
the installation, construction or operation of
the equipment and the hazards involved. In
addition, this person has the following
qualifications:
I s trained and authorized to
de-energize, clear, ground and tag
circuits and equipment in accordance
with established safety procedures.
I s trained in the proper care and use of
protective equipment, such as: rubber
gloves, hard hat, safety glasses or face
shields, flash clothing, etc., in
accordance with established safety
practices.
Is trained in rendering first aid.
Further, a qualified person shall also be
familiar with the proper use of special
precautionary techniques, personal
protective equipment, insulation and
shielding materials, and insulated tools and
test equipment. Such persons are permitted
to work within limited approach of exposed
live parts operating at 50 volts or more, and
shall, at a minimum, be additionally trained
in all of the following:
T
he skills and techniques necessary to
distinguish exposed energized parts from
other parts of electric equipment
T
he skills and techniques necessary to
determine the nominal voltage of
exposed live parts
T
he approach distances specified in NFPA
70E® and the corresponding voltages to
which the qualified person will be
exposed
T
he decision-making process necessary
to determine the degree and extent of
the hazard and the personal protective
equipment and job planning necessary to
perform the task safely.
Note:
These instructions do not purport to cover all
details or variations in equipment, nor to
provide for every possible contingency to be
met in connection with installation, operation
or maintenance. Should further information be
desired or should particular problems arise
that are not covered sufficiently for the
purchaser’s purposes, the matter should be
referred to the local sales office.
The contents of this instruction manual shall
not become part of or modify any prior or
existing agreement, commitment or
relationship. The sales contract contains the
entire obligation of Siemens Industry, Inc. The
warranty contained in the contract between
the parties is the sole warranty of Siemens
Industry, Inc. Any statements contained herein
do not create new warranties or modify the
existing warranty.
Table of contents
Introduction
04 – 05
Receiving, handling and storage
06 – 08
Installation checks and functional tests
09 – 13
Vacuum interrupter/operator
14 – 39
Maintenance
40 – 52
Overhaul
53 – 58
Technical data and troubleshooting
Appendix
59 – 61
62 – 67
Introduction
Hazardous voltages and high speed moving parts.
Will cause death, serious injury or property damage.
Always de-energize and ground the equipment before maintenance.
Read and understand this instruction manual before using equipment.
Maintenance should be performed only by qualified personnel. The use
of unauthorized parts in the repair of the equipment or tampering by
unqualified personnel will result in dangerous conditions which will
cause death, severe injury or equipment damage. Follow all safety
instructions contained herein.
Introduction
The type 38-3AH3 family of vacuum circuit
breakers is designed to meet all applicable
ANSI, NEMA and IEEE standards. Successful
application and operation of this equipment
depends as much upon proper installation
and maintenance by the user as it does
upon the proper design and fabrication by
Siemens.
The purpose of this instruction manual is to
assist the user in developing safe and
efficient procedures for the installation,
maintenance and use of the equipment.
Contact the nearest Siemens representative
if any additional information is desired.
Signal words
The signal words “danger,” “warning” and
“caution” used in this manual indicate the
degree of hazard that may be encountered
by the user. These words are defined as:
Danger - Indicates an imminently hazardous
situation that, if not avoided, will result in
death or serious injury.
Warning - Indicates a potentially hazardous
situation that, if not avoided, could result in
death or serious injury.
Caution - Indicates a potentially hazardous
situation that, if not avoided, may result in
minor or moderate injury.
Caution (without safety alert symbol) Indicates a potentially hazardous situation
that, if not avoided, may result in property
damage.
4
Hazardous Procedures
In addition to other procedures described in
this instruction manual as dangerous, user
personnel must adhere to the following:
1. A
lways work only on a de-energized
circuit breaker. The circuit breaker should
be isolated, grounded and have all
control power removed before
performing any tests, maintenance or
repair.
2. A
lways perform maintenance on the
circuit breaker after the spring-charged
mechanisms are discharged (except for
test of the charging mechanisms). Check
to be certain that the indicator flags read
OPEN and DISCHARGED.
Field service operation and warranty
issues
Siemens can provide competent, welltrained field service representatives to
provide technical guidance and advisory
assistance for the installation, overhaul,
repair and maintenance of Siemens
equipment, processes and systems. Contact
regional service centers, sales offices or the
factory for details, or telephone Siemens
field service at 1-800-347-6659 or 1-919365-2200 outside the U.S.
For medium voltage customer service
issues, contact Siemens at 1-800-347-6659
or 1-919-365-2200 outside the U.S.
3. Always let an interlock device or safety
mechanism perform its function without
forcing or defeating the device.
5
Receiving, handling
and storage
Heavy weight.
Improper lifting or hoisting can result in death, serious injury or
property damage.
Obtain the services of a qualified rigger prior to hoisting the circuit
breaker to assure adequate safety margins in the hoisting equipment
and procedures to avoid damage.
Introduction
This portion of the instruction manual
covers the receiving, handling and storage
instructions for a type 38-3AH3 vacuum
circuit breaker shipped separately from the
switchgear. This section of the instruction
manual is intended to help the user identify,
inspect and protect the circuit breaker prior
to its installation.
Receiving procedure
Make a physical inspection of the shipping
container before removing or unpacking the
circuit breaker.
Check for shipment damage or indications
of rough handling by the carrier. Check each
item against the manifest to identify any
shortages.
Accessories such as the manual charging
crank, the racking crank and the split plug
jumper are shipped separately.
6
Shipping damage claims
Important: The manner in which visible
shipping damage is identified by consignee
prior to signing the delivery receipt can
determine the outcome of any damage
claim to be filed.
Notification to carrier within 15 days for
concealed damage is essential if loss
resulting from unsettled claims is to be
eliminated or minimized.
1. W
hen the shipment arrives, note
whether the equipment is properly
protected from the elements. Note the
trailer number the equipment arrived on.
Note also any blocking of equipment.
During unloading, check the actual
equipment delivered to verify it agrees
with the delivery receipt.
ake immediate inspection for visible
2. M
damage upon arrival and prior to
disturbing or removing packaging or
wrapping material. This should be done
prior to unloading when possible. When
total inspection cannot be made on
vehicle prior to unloading, close
inspection during unloading must be
performed and visible damage noted on
the delivery receipt. Take pictures if
possible.
3. A
ny visible damage must be noted on the
delivery receipt and acknowledged with
the driver’s signature. The damage should
be detailed as much as possible. It is
essential that a notation "possible
internal damage, subject to inspection"
be included on the delivery receipt. If the
driver will not sign the delivery receipt
with the damage noted, the shipment
should not be signed for by the
consignee or their agent.
4. N
otify Siemens medium-voltage
customer service immediately of any
damage, at 1-800-347-6659 or 1-919365-2200 outside the U.S.
5. Arrange for a carrier inspection of the
damage immediately.
Important: Do not move the equipment
from the place it was set when unloading.
Also, do not remove or disturb packaging or
wrapping material prior to carrier damage
inspection. Equipment must be inspected by
carrier prior to handling after receipt. This
eliminates loss due to claims by carrier that
the equipment was damaged or further
damaged on site after unloading.
6. Be sure the equipment is properly
protected from any further damage by
covering it properly after unloading.
7. If practical, make further inspection for
possible concealed damage while the
carrier’s inspector is on site. If inspection
for concealed damage is not practical at
the time the carrier’s inspector is
present, it must be done within 15 days
of receipt of the equipment. If concealed
damage is found, the carrier must again
be notified and inspection made prior to
taking any corrective action to repair.
Also notify Siemens immediately at
1-800-347-6659 or 1-919-365-2200
outside the U.S.
8. O
btain the original carrier inspection
report and forward it with a copy of the
noted delivery receipt to Siemens.
Approval must be obtained by Siemens
from the carrier before any repair work
can be performed.
Before approval can be obtained, Siemens
must have the documents referenced in
the paragraph above. The carrier
inspection report and/or driver’s signature
on the delivery receipt does not constitute
approval to repair.
Note: Shipments are not released from the
factory without a clear bill of lading.
Approved methods are employed for
preparation, loading, blocking and tarping
of the equipment before it leaves the
Siemens factory. Any determination as to
whether the equipment was properly loaded
or properly prepared by shipper for over-theroad travel cannot be made at the
destination. If the equipment is received in a
damaged condition, this damage to the
equipment has to have occurred while en
route due to conditions beyond Siemens‘
control. If the procedure outlined above is
not followed by the consignee, purchaser or
their agent, Siemens cannot be held liable
for repairs. Siemens will not be held liable
for repairs in any case where repair work
was performed prior to authorization from
Siemens.
Handling procedure
arefully remove the shipping carton
1. C
from the circuit breaker. Keep the
shipping pallet for later use if the circuit
breaker is to be stored prior to its
installation.
2. Inspect for concealed damage.
Notification to carrier must take place
within 15 days to assure prompt
claim resolution.
3. E
ach circuit breaker should be lifted
appropriately to avoid crushing the side
panels of the circuit breaker, or
damaging the primary disconnect
assemblies.
Type 38-3AH3 vacuum circuit breakers
weigh between 800 and 1,050 lbs
(364-478 kg), plus an additional 125 lbs
(57 kg) for the pallet and packaging.
4. T
he palleted circuit breaker can be
moved using a properly rated fork-lift
vehicle. The pallets are designed for
movement by a standard fork-lift vehicle.
7
Storage procedure
1. Whenever possible, install the circuit
breaker in its assigned switchgear
enclosure for storage. Follow instructions
contained in the type GM38 38 kV metalclad switchgear instruction manual,
E50001-F710-A236-X-XXXX.
A
B
E
F
C
D
Item
Description
A
Manual spring-charging port
B
CHARGED/DISCHARGED indicator
C
OPEN/CLOSED indicator
D
Operation counter
E
Manual close pushbutton
F
Manual open pushbutton
Figure 1: Type 38-3AH3 vacuum circuit breaker front panel controls
8
2. W
hen the circuit breaker needs to be
placed on its pallet for storage, be sure
the unit is securely bolted to the pallet
and covered with polyethylene film at
least 10 mils thick.
Indoor storage
Whenever possible, store the circuit breaker
indoors. The storage environment must be
clean, dry and free of such items as
construction dust, corrosive atmosphere,
mechanical abuse and rapid temperature
variations.
Outdoor storage
Outdoor storage is not recommended. When
no other option is available, the circuit
breaker must be completely covered and
protected from rain, snow, dirt and all other
contaminants.
Space heating
Space heating must be used for both indoor
and outdoor storage to prevent
condensation and corrosion. When the
circuit breaker is stored outdoors, 250 watts
per circuit breaker of space heating is
recommended. If the circuit breaker is
stored inside the switchgear enclosure, and
the switchgear is equipped with space
heaters, energize the space heaters.
Installation checks
and functional tests
Hazardous voltage and high-speed moving parts.
Will cause death, serious injury and property damage.
Read instruction manuals, observe safety instructions and use qualified
personnel.
Introduction
This section provides a description of the
inspections, checks and tests to be
performed on the circuit breaker prior to
operation in the metal-clad switchgear.
Inspections, checks and tests without
control power
Vacuum circuit breakers are normally
shipped with their primary contacts OPEN
and their springs DISCHARGED. However, it
is critical to first verify the DISCHARGED
condition of the spring-loaded mechanisms
after de-energizing control power.
De-energizing control power in
switchgear
When the circuit breaker is mounted in
switchgear, open the control-power
disconnect device in the metal-clad
switchgear cubicle.
The control-power disconnect device is
normally located on the secondary-device
panel in the upper cell of the vertical
section. The normal control-power
disconnect device is a pullout-type fuse
holder. Removal of the fuse holder
de-energizes control power to the circuit
breaker in the associated switchgear cell. In
some switchgear assemblies, a molded-case
circuit breaker or knife switch is used in lieu
of the pullout-type fuse holder.
Opening this circuit breaker or switch
accomplishes the same result: control power
is disconnected.
Spring-discharge check (refer to Figure 1:
Type 38-3AH3 vacuum circuit breaker
front panel controls on page 8)
Perform the spring-discharge check before
removing the circuit breaker from the pallet
or removing it from the switchgear.
The spring-discharge check should be
performed after de-energizing control
power. This check assures both the tripping
and closing springs are fully discharged.
Note: Do not perform the spring-discharge
check if the circuit breaker is in the
CONNECT position. Open the circuit breaker
and rack to the DISCONNECT position, and
then perform the spring-discharge check.
ress red trip pushbutton.
1. P
2. P
ress black close pushbutton.
ress red trip pushbutton again.
3. P
4. V
erify spring-condition indicator shows
DISCHARGED.
5. V
erify main contact status indicator
shows OPEN.
9
Heavy weight.
Can result in death, serious injury or property damage.
Observe all handling instructions in this instruction manual to prevent
tipping or dropping of equipment.
Removal from cell in indoor switchgear if
not on raised pad and Shelter-Clad
outdoor switchgear
After performing the spring discharge check
(with control power de-energized), remove
the circuit breaker from its switchgear
cubicle.
Removal from cell in outdoor non-walk-in
enclosures or for indoor switchgear
installed on a raised pad
Removal of the circuit breaker from a nonwalk-in outdoor-switchgear assembly is
similar to removal of a circuit breaker at
floor level with several additional steps.
1. Insert the racking crank on the racking
screw on the front of the circuit breaker
cell, and push in (refer to "Racking crank
engagement procedure" on page 11).
This action operates the racking-interlock
latch. Figure 2 shows circuit breaker
racking.
Figure 3 shows the two extension rails
inserted into the fixed rails within the cell.
The rails engage locking pins in the fixed
rails to secure them in position. The
procedure for removal of a circuit breaker
not located at floor level is:
2. R
otate the racking crank
counterclockwise until the circuit breaker
is in the DISCONNECT position, as
indicated on the racking mechanism.
3. M
ove the circuit breaker release latch (on
the floor of the cell near the right side of
the circuit breaker) to the left and pull
the circuit breaker out from the
DISCONNECT position. The circuit breaker
can now be removed from the cubicle.
4. T
he circuit breaker is now free to be
rolled out onto the floor using the
handles on the front. The wheels of the
circuit breaker are at floor level (unless
the switchgear is installed on a raised
pad), and one person can normally
handle the unit.
10
1. Close the circuit-breaker compartment
door and secure all latches.
2. Insert the racking crank onto the racking
screw on the front of the circuit-breaker
cell, and push in (refer to "Racking crank
engagement procedure" on page 11).
This action operates the racking-interlock
latch.
3. Rotate the racking crank
counterclockwise until the circuit breaker
is in the DISCONNECT position.
4. O
pen the circuit-breaker compartment
door and insert the two extension rails
into the fixed rails. Be sure the extension
rails are properly secured in place.
5. M
ove the circuit-breaker release latch (on
the floor of the cell near the right side of
the circuit breaker) to the left and pull
the circuit breaker out from the
DISCONNECT position. The circuit breaker
can now be removed from the cubicle
and rolled out onto the two extension
rails.
Heavy weight.
Can result in death, serious injury or property damage.
Do not transport a circuit breaker using a lift truck with the lift truck in
the raised position.
6. R
emove the circuit breaker from the two
extension rails using the approved
Siemens circuit-breaker lifting device or
Siemens lifting sling and a suitable
crane.
7. L ift the two extension rails and withdraw
them from the switchgear.
8. C
lose the circuit-breaker compartment
door and secure all latches.
Type 38-3AH3 vacuum circuit breakers
weigh between 800 and 1,050 lbs
(364-478 kg) depending upon ratings. The
circuit breaker can be moved using a
properly rated crane and lift sling. A lift sling
can be attached to the circuit breaker, and
then used to hoist the circuit breaker
vertically clear of the extension rails. When
clear, remove the rails and lower the circuit
breaker to the floor.
Racking crank engagement procedure
A crank for racking the circuit breaker is
provided as a standard accessory. Racking a
circuit breaker can be accomplished with the
drawout-compartment-front door open or
through a small opening (or window) in the
front door, with the door closed. Racking a
rollout-fuse truck is accomplished with the
compartment-front door open.
Figure 3: Use of extension rails for
voltage transformer (VT) fuserollout truck or circuit breaker not at
floor level (VT fuse-rollout truck in
upper cell shown. Procedure for
circuit breaker in lower cell but not
at floor level is similar.)
The racking crank consists of an offset
handle with a custom socket assembly
welded to the end. The socket end of the
crank is designed to engage the shoulder of
the racking-mechanism shaft and remain
engaged during racking with spring
plungers. The plungers operate in a manner
similar to the retainers of an ordinary
mechanic’s socket wrench.
The portion of the racking-mechanism shaft
visible is cylindrical, and the shoulder of the
racking-mechanism shaft is hidden by a
shroud until the engagement procedure
starts. The square socket-end of the crank
will only engage the shoulder of the shaft if
it is aligned properly.
Figure 2: Type 38-3AH3 vacuum circuit breaker
racking
11
The suggested procedure to engage the
racking mechanism is as follows:
1. The circuit breaker must be OPEN. (The
racking shroud cannot be moved if the
circuit breaker is CLOSED.)
2. H
old the socket-end of the crank in one
hand and the crank handle in the other
hand.
3. Place the socket over the end of the
racking-mechanism shaft. Align the
socket with the shoulder on the rackingmechanism shaft.
Note: If the socket is not aligned, the socket
will not be able to engage the shoulder of
the racking-mechanism shaft.
4. Once alignment is achieved, firmly push
the crank and socket assembly toward
the racking mechanism.
5. When properly engaged, the crank
should remain connected to the racking
mechanism. If the crank does not remain
in position, adjust the spring plungers
clockwise one-half turn. This will
increase the contact pressure of the
spring plungers.
6. To remove the crank, pull the assembly
off of the racking-mechanism shaft.
Note: If the effort to rack the circuit breaker
increases considerably during racking, or if
turning of the racking crank requires
excessive force, stop racking immediately.
Do not try to force the racking crank to
rotate, or parts of the circuit breaker or
racking mechanism could be damaged.
Determine the source of the problem and
correct it before continuing with racking.
Figure 4: Manual charging of the
closing springs
12
Physical inspections
1. Verify the rating of the circuit breaker is
compatible with both the system and the
switchgear.
2. Perform a visual-damage check. Clean
the circuit breaker of all dust, dirt and
foreign material.
Manual-spring charging check
1. Insert the manual-spring charging crank
into the manual-charge handle socket as
shown in Figure 4. Turn the crank
clockwise (about 48 revolutions) until
the spring condition indicator shows the
closing spring is CHARGED.
2. Repeat the spring discharge check.
3. Verify the springs are DISCHARGED and
the circuit-breaker primary contacts are
OPEN by indicator positions.
As-found and vacuum-integrity check
tests
Perform and record the results of both the
as-found insulation test and the vacuumintegrity check (dielectric) test. Procedures
for these tests are described in the
Maintenance section of this instruction
manual pages 40-52.
Automatic spring-charging check
Refer to the specific wiring information and
rating label for your circuit breaker to
determine the voltage required and where
the control-voltage signal should be applied.
Usually, spring-charging power is connected
to secondary-disconnect fingers SD16 and
SD15, closing control power to SD13 and
SD15 and tripping power to SD1 and SD2.
When control power is connected to the
type 38-3AH3 vacuum circuit breaker, the
closing springs should automatically charge,
if the racking crank is not engaged.
Note: Secondary-disconnect terminals are
numbered 1-16, from right to left.
The automatic spring-charging features of
the circuit breaker must be checked. Control
power is required for automatic springcharging to take place.
pen control-power circuit by opening
1. O
the control-power disconnect device.
2. Install the circuit-breaker end of the splitplug jumper (if furnished) to the circuit
breaker as shown in Figure 5: Split-plug
jumper connected to circuit breaker. The
split-plug jumper is secured over the
circuit-breaker secondary contacts with
thumb screws.
3. Install the switchgear end of the splitplug jumper to the secondary-disconnect
block inside the switchgear cubicle as
shown in Figure 6: Split-plug jumper
connected to switchgear. The jumper
slides into place and interconnects all
control power and signal leads (for
example, electrical trip and close
contacts) between the switchgear and
the circuit breaker.
4. E
nergize (close) the control-power circuit
disconnect.
7. P
erform the spring discharge check
again. Verify the closing springs are
DISCHARGED and the primary contacts of
the type 38-3AH3 vacuum circuit breaker
are OPEN.
Final mechanical inspections without
control power
1. Make a final mechanical inspection of
the circuit breaker. Verify the contacts
are in the OPEN position, and the closing
springs are DISCHARGED.
Figure 5: Split-plug jumper
connected to circuit breaker
2. Check the upper- and lower-primary
studs and contact fingers shown in
Figure 7: Circuit breaker primary
disconnect. Verify mechanical condition
of finger springs and the disconnect
studs, check for loose hardware,
damaged or missing primary-disconnect
contact fingers and damaged disconnect
studs.
3. Coat movable primary-contact fingers
(refer to Figure 7: Circuit breaker primary
disconnect) and the secondarydisconnect contacts (refer to Figure 23:
Construction of secondary shunt release
(shown charged) on page 30) with a
light film of Siemens contact lubricant
number 15-172-791-233.
Figure 6: Split-plug jumper
connected to switchgear
4. The type 38-3AH3 vacuum circuit breaker
is ready for installation into its assigned
cubicle of the metal-clad switchgear.
Refer to removal procedures and install
the circuit breaker into the switchgear.
5. Refer to the switchgear instruction
manual for functional tests of an
installed circuit breaker.
Figure 7: Circuit breaker
primary disconnects
se the close and trip controls (refer to
5. U
Figure 1: Type 38-3AH3 vacuum circuit
breaker front panel controls on page 8)
to first close and then open the circuitbreaker contacts. Verify the contact
positions visually by observing the OPEN/
CLOSED indicator on the circuit breaker.
6. D
e-energize control power by repeating
Step 1. Disconnect the split-plug jumper
from the switchgear before
disconnecting the circuit-breaker end.
13
Vacuum interrupter/
operator
Figure 8: Front view of type 38-3AH3 vacuum circuit breaker with front panel removed
Item
C
Description
A
Gearbox
B
Opening spring
C
Secondary
disconnect
D
Push-to-close
E
Auxiliary switch
F
Close coil
G
Trip coil
H
Push-to-trip
I
Mechanismoperated cell (MOC)
switch operator
J
Ground disconnect
K
Trip-free interlock
L
Closed circuitbreaker interlock
M
Capacitor trip
(optional)
N
Jack shaft
O
Operations counter
P
OPEN/CLOSED
indicator
Q
CHARGED/
DISCHARGED
indicator
R
Spring-charging
motor (behind limit
switches)
S
Closing spring
A
D
F
S
B
E
G
H
Q
R
I
P
N
O
M
L
14
G
K
J
Introduction
The type 38-3AH3 vacuum circuit breaker is
of drawout construction, designed for use in
medium-voltage, metal-clad switchgear. The
38-3AH3 circuit breaker conforms to the
requirements of ANSI and IEEE standards,
including C37.20.2, C37.04, C37.06, C37.09
and C37.010.
A type 38-3AH3 vacuum circuit breaker
consists of three vacuum interrupters, a
stored-energy operating mechanism,
necessary electrical controls and interlock
devices, disconnect devices to connect the
circuit breaker to both primary and control
power and an operator housing. Insulating
barriers are located along the outer sides
and between phases as shown in Figure 11:
Type 38-3AH3 vacuum circuit breaker with
inter-phase and outer-phase barriers
installed on page 17.
This section describes the operation of each
major sub-assembly as an aid in the
operation, installation, maintenance and
repair of the type 38-3AH3 vacuum
circuit breaker.
1
Item
Description
1
Fixed contact-current connection
2
Ceramic insulator
2
4
3
5
3
Arc shield
4
Fixed contact
5
Moving contact
6
Ceramic insulator
7
Metal bellows
8
6
9
Guide
Moving contact-current connection
7
8
9
Figure 9: Vacuum interrupter cutaway view
Vacuum interrupters
The operating principle of the vacuum
interrupter is simple. Figure 9: Vacuum
interrupter cutaway view is a cutaway view
of a typical vacuum interrupter. The entire
assembly is sealed after a vacuum is
established. The vacuum-interrupter
stationary contact is connected to the
upper-disconnect stud of the circuit breaker.
The vacuum-interrupter movable contact is
connected to the lower-disconnect stud and
driving mechanism of the circuit breaker.
The metal bellows provides a secure seal
around the movable contact, preventing loss
of vacuum while permitting vertical motion
of the movable contact.
When the two contacts separate, an arc is
initiated that continues conduction up to
the following current zero. At current zero,
the arc extinguishes and any conductive
metal vapor that has been created by and
supported by the arc condenses on the
contacts and on the surrounding arc shield.
Contact materials and configuration are
optimized to achieve arc motion, resist
welding and to minimize switching
disturbances.
15
Phase barriers
Figure 11: Type 38-3AH3 vacuum circuit
breaker with inter-phase and outer-phase
barriers installed on page 17 is a rear view
of a type 38-3AH3 vacuum circuit breaker
that shows the outer- (phase-to-ground) and
inter-phase-insulating barriers. These glasspolyester insulating barriers are attached to
the circuit-breaker frame and provide
suitable electrical insulation between the
vacuum-interrupter primary circuits and the
housing.
Figure 10: Upper and lower primary disconnects (outer-phase barrier removed)
Primary disconnects
Figure 10: Upper and lower primary
disconnects (outer-phase barrier removed)
is a side view of the circuit breaker with the
outer-insulating phase barrier removed to
show details of the primary disconnects.
Each circuit breaker has three upper- and
three lower-primary disconnects. Upperprimary disconnects are connected to the
stationary contacts of the vacuum
interrupters, and the lower-primary
disconnects are connected to the movable
contacts. Each disconnect arm has a set of
multiple spring-loaded fingers that mate
with bus bars in the metal-clad switchgear.
The number of fingers in the disconnect
assembly varies with the continuous and/or
interrupting rating of the circuit breaker.
There are three insulating push rods. Each
push rod connects the movable contact of
one of the vacuum interrupters to the jack
shaft driven by the closing and tripping
mechanism. Flexible connectors provide
secure electrical connections between
the movable contacts of each vacuum
interrupter and its bottom-primary
disconnect.
16
Stored-energy operating mechanism
The stored-energy operating mechanism of
the type 38-3AH3 vacuum circuit breaker is
an integrated arrangement of springs,
solenoids and mechanical devices designed
to provide a number of critical functions.
The energy necessary to close and open
(trip) the contacts of the vacuum
interrupters is stored in powerful tripping
and closing springs. The closing springs are
normally charged automatically, but there
are provisions for manual charging. The
operating mechanism that controls
charging, closing and tripping functions is
fully trip-free. Trip-free requires that the
tripping function prevail over the closing
function as specified in ANSI/IEEE C37.041999, clause 6.9. The operation of the
stored-energy mechanism will be discussed
later in this section.
The vacuum circuit breaker consists of two
sub-assemblies. The “interrupter/operator”
module is a unitized assembly of the three
vacuum interrupters, primary insulators and
operating mechanism. The second module,
the “vehicle”, is the supporting drawoutstructure module for the operating
mechanism. The vehicle provides primarystud extensions, closed circuit-breaker
racking interlocks, closing spring discharge
feature and other requirements needed to
ensure safe and reliable use during racking
and during operation. These two subassemblies will be separately described.
Interrupter/operator module
The interrupter/operator module consists of
the three poles, each with its vacuum
interrupter and primary insulators, mounted
on the common motor or hand-charged
spring-stored energy-operating-mechanism
housing. This module is shown in Figure 12:
Interrupting/operating mechanism module
(shown with outer-phase barrier removed).
Construction
Refer to Figure 12: Interrupting/operating
mechanism module (shown with outerphase barrier removed) on page 17, Figure
13: Operating mechanism controls and
indicators on page 18, Figure 14: Type
38-3AH3 vacuum circuit breaker pole
section on page 19 and Figure 15: Storedenergy operating mechanism on page 20.
Each of the circuit breaker poles is fixed to
the rear of the operating-mechanism
housing (60.0) by two cast-resin
insulators (16.0).
The insulators also connect to the upper
(20.0) and lower (40.0) pole-supports that
in turn support the ends of the vacuum
interrupter (30.0). Primary stud-extensions
are attached directly to the upper polesupport (20.0) and lower terminal (29.0).
The energy-storing mechanism and all the
control and actuating devices are installed
in the mechanism housing (60.0). The
mechanism is of the spring stored-energy
type and is mechanically and electrically
trip-free.
The OPEN/CLOSED indicator (58.0),
CHARGED/DISCHARGED indicator (55.0) and
the operations counter (59.0) are located on
the front of the mechanism housing (60.0).
Figure 11: Type 38-3AH3 vacuum circuit breaker with inter-phase and outer-phase barriers
installed
Figure 12: Interrupter/operating mechanism module (shown with outer-phase barrier
removed)
Item
Description
16.0
Insulator
20.0
Pole head
30.0
Vacuum
interrupter
40.0
Pole bottom
60.0
Operator
housing
20.0
16.0
60.0
30.0
16.0
40.0
17
Figure 13: Operating mechanism
controls and indicators
Item
Description
53.0
Manual close button
54.0
Manual open (trip) button
55.0
CHARGED/DISCHARGED indicator
58.0
OPEN/CLOSED indicator
59.0
Operations counter
Circuit-breaker pole
Refer to Figure 14: Type 38-3AH3 vacuum
circuit breaker pole section on page 19. The
vacuum interrupter (30.0) is rigidly
connected to the upper terminal and pole
support (20.0) by its terminal bolt (31.2).
The lower part of the vacuum interrupter is
stabilized against lateral forces by a
centering ring (28.1) on the pole-support
(40.0). The external forces due to switching
operations and the contact pressure are
absorbed by the struts (28.0).
Current-path assembly
Refer to Figure 14: Type 38-3AH3 vacuum
circuit breaker pole section on page 19. The
current-path assembly consists of the upper
terminal and pole support (20.0), the
stationary contact (31.0) and the moving
contact (36.0), that is connected with the
lower terminal (29.0) by terminal clamp
(29.2) and a flexible shunt (29.1).
Vacuum interrupter
Refer to Figure 9: Vacuum interrupter
cutaway view on page 15. The movingcontact (36.0) motion is aligned and
stabilized by guide bushing (35.0). The
metal bellows (34.0) follows the travel of
contact (36.0) and seals the vacuum
interrupter against the surrounding
atmosphere.
18
53.0
55.0
58.0
59.0
54.0
Switching operation
Refer to Figure 14: Type 38-3AH3 vacuum
circuit breaker pole section on page 19.
When a closing command is initiated, the
closing spring, that was previously charged
by hand or by the motor, actuates the
moving contact (36.0) through jack shaft
(63.0), lever (63.7), insulated coupler (48.0)
and lever (48.6).
The motion of the insulated coupler is
converted into the vertical movement of the
moving contact.
The moving-contact motion is controlled by
the guide link (48.9), that pivots on support
(40.0) and the eye bolt (36.3).
During closing, the tripping spring and the
contact-pressure springs (49.0) are charged
and latched by the pawl (64.1). The closing
spring is recharged immediately after
closing.
In the CLOSED state, the necessary contact
pressure is maintained by the contactpressure spring and the atmospheric
pressure. The contact-pressure spring
automatically compensates for contact
erosion, which is very small.
When a tripping command is given, the
energy stored in the tripping- and contactpressure springs is released by pawl (64.2).
The opening sequence is similar to the
closing sequence. The residual force of the
tripping spring arrests the moving contact
(36.0) in the OPEN (TRIPPED) position.
Figure 14: Type 38-3AH3 vacuum circuit breaker pole section
20.0
27.0
31.2
16.0
60.0
30.0
31.0
36.0
28.0
64.2
63.0
63.7
28.1
29.1
16.0
29.2
36.3
29.0
40.0
48.9
48.6
48.0
49.0
Item
Description
16.0
Insulator
20.0
Pole head
27.0
Upper connection
terminal
28.0
Strut
29.0
Lower connection
terminal
29.1
Flexible connector
29.2
Terminal clamp
30.0
Vacuum interrupter
31.0
Stationary contact
31.2
Upper terminal bolt
34.0
Bellows (not shown)
35.0
Guide bushing
(not shown)
36.0
Moving contact
36.3
Eye bolt
40.0
Pole bottom
48.0
Insulating coupler
48.6
Angled lever
48.9
Guide link
49.0
Contact pressure
spring
60.0
Operator housing
63.0
Jack shaft
63.7
Lever
64.1
Pawl (not shown)
64.2
Pawl
19
Figure 15: Stored-energy operating mechanism
50.3.1
62.3
50.3
55.2
62.5
62.2
62.5.2
50.2
62.6
50.1
53.0
55.1
62.0
68.0
53.1
50.4.1
54.1
64.0
55.0
54.0
64.2
64.3.1
50.4
68.1
62.8
58.0
63.0
63.7
63.5
59.0
64.3
63.1
60.0
61.8
Item
Description
Item
Description
Item
Description
50.1
Manual-spring charging port
55.1
Linkage
62.8
Trip-free coupling rod
50.2
Charging-mechanism gear box
55.2
Control lever
63.0
Jack shaft
Phase C lever
50.3
Charging flange
58.0
CLOSED/OPEN indicator
63.1
50.3.1
Driver
59.0
Operations counter
63.5
Phase B lever
50.4
Spring-charging motor (behind limit switches)
60.0
Operator housing
63.7
Phase A lever
50.4.1
Limit switches
61.8
Shock absorber
64.0
Opening spring
53.0
Close pushbutton
62.0
Closing spring
64.2
Pawl
53.1
Close coil
62.2
Crank
64.3
Lever
54.0
Open pushbutton
62.3
Cam disc
64.3.1
Pawl roller
68.0
Auxiliary switch
68.2
Linkage
20
54.1
Trip coil
62.5
Lever
54.2
Undervoltage release(not shown)
62.5.2
Close-latch pawl
55.0
Spring-charge indicator
62.6
Driver lever
Operating mechanism
The operating mechanism is comprised of
the mechanical and electrical components
required to:
1. C
harge the closing springs with sufficient
potential energy to close the circuit
breaker and to store opening energy in
the tripping- and contact-pressure
springs.
2. M
eans to initiate closing and tripping
actions.
3. M
eans of transmitting force and motion
to each of three poles.
4. O
perate all of these functions
automatically through electrical-charging
motor, cutout switches, anti-pump relay,
release (close and trip) solenoids and
auxiliary switches.
5. P
rovide indication of the circuit breaker
status (OPEN/CLOSED), spring condition
(CHARGED/DISCHARGED) and number of
operations.
Construction
The essential parts of the operating
mechanism are shown in Figure 15: Storedenergy operating mechanism on page 20.
The control and sequence of operation of
the mechanism is described in the
Operating mechanism section diagrams in
Figure 17-21 on pages 24 through 28.
Indirect releases (tripping coils)
The shunt releases (54.1) convert the
electrical-tripping pulse into mechanical
energy to release the trip latch and open the
circuit breaker.
The undervoltage release (optional) (54.2)
may be electrically actuated by a make or a
break contact.
If a make contact is used, the coil is shorted
out, and a resistor must be used to limit the
current. The undervoltage-release option
mounts to the immediate right of the trip
coil (54.1).
Motor-operating mechanism
The spring-charging motor (50.4) is bolted
to the charging-mechanism (50.2) gear box
installed in the mechanism housing. Neither
the gear-box mechanism nor the motor
require any normal maintenance.
Auxiliary switch
The auxiliary switch (68.0) is actuated by
the jack shaft (63.0) and link (68.1).
Mode of operation
The operating mechanism is of the storedenergy trip-free type. In other words, the
charging of the closing spring is not
automatically followed by the contacts
changing position, and the tripping function
prevails over the closing function in
accordance with ANSI/IEEE C37.04-1999,
clause 6.9.
When the stored-energy mechanism has
been charged, the circuit breaker can be
closed manually or electrically at any desired
time. The mechanical energy for carrying
out an "open-close-open" sequence for autoreclosing duty is stored in the closing and
tripping springs.
Charging
The details of the closing-spring charging
mechanism are shown in Figure 15: Storedenergy operating mechanism on page 20.
The charging shaft is supported in the
charging mechanism (50.2), but is not
coupled mechanically with the charging
mechanism.
Fitted to it are the crank (62.2) at one end,
and the cam (62.3), together with lever
(62.5) at the other.
When the charging mechanism is actuated
by hand with a hand crank or by a motor
(50.4), the flange (50.3) turns until the
driver (50.3.1) locates in the cutaway part
of the cam disc (62.3), thus causing the
charging shaft to follow. The crank (62.2)
charges the closing spring (62.0).
When the closing spring has been fully
charged, the crank actuates the linkage
(55.1) via control lever (55.2) for the
closing-spring CHARGED indicator (55.0),
and actuates the limit switches (50.4.1) for
interrupting the motor supply.
At the same time, the lever (62.5) at the
other end of the charging shaft is securely
locked by the close-latch pawl (62.5.2).
When the closing spring is being charged,
cam disc (62.3) follows along, and it is
brought into position for closing when the
closing spring is fully charged.
21
53.0
50.1
50.0
55.0
54.0
Item
Description
50.0
Hand crank
50.1
Manual spring-charging port
53.0
Manual close pushbutton
54.0
Manual open (trip) pushbutton
55.0
CHARGED/DISCHARGED indicator
Figure 16: Use of manual-spring operation crank
Closing
Refer to Figure 15: Stored-energy operating
mechanism on page 20, Figure 16: Use of
manual-spring operating crank on page 22,
Figure 17: Operating mechanism section
diagram (drawout trip-free linkage shown)
mechanism OPEN, closing spring
DISCHARGED on page 24, Figure 18:
Operating mechanism section diagram
(drawout trip-free linkage shown)
mechanism OPEN, closing spring
DISCHARGED on page 25, Figure 19:
Operating mechanism section diagram
(drawout trip-free linkage shown)
mechanism CLOSED, closing spring
DISCHARGED on page 26 and Figure 20:
Operating mechanism section diagram
(drawout trip-free linkage shown)
mechanism CLOSED, closing spring
CHARGED on page 27.
If the circuit breaker is to be closed locally,
the closing spring is released by pressing the
close button (53.0). In the case of electrical
control, the spring-release coil 52SRC (53.1)
unlatches the closing spring.
As the closing spring discharges, the
charging shaft is turned by crank (62.2). The
cam disc (62.3) at the other end of the
charging shaft actuates the drive lever
(62.6), with the result that the jack shaft
(63.0) is turned by lever (63.5) via the
coupling rod (62.8).
At the same time, the levers (63.1), (63.5)
and (63.7) fixed on the jack shaft operate
the three insulated-couplers for the circuitbreaker poles.
Lever (63.7) changes the OPEN/CLOSED
indicator (58.0) to CLOSED. Lever (63.5)
charges the tripping spring (64.0) during
closing, and the circuit breaker is latched in
the CLOSED position by lever (64.3) with
pawl roller (64.3.1) and by pawl (64.2).
Lever (63.1) actuates the auxiliary switch
through the linkage (68.1).
The crank (62.2) on the charging shaft
moves the linkage (55.1) by acting on the
control lever (55.2). The closing-spring
CHARGED indication (55.0) is thus canceled
and, the limit switches (50.4.1) switch in
the control supply to cause the closing
spring to recharge immediately.
22
Trip-free functionality
Refer to Figure 15: Stored-energy operating
mechanism on page 20, Figure 17:
Operating mechanism section diagram
(drawout trip-free linkage shown)
mechanism OPEN, closing spring
DISCHARGED on page 24, Figure 18:
Operating mechanism section diagram
(drawout trip-free linkage shown)
mechanism OPEN, closing spring
DISCHARGED on page 25, Figure 19:
Operating mechanism section diagram
(drawout trip-free linkage shown)
mechanism CLOSED, closing spring
DISCHARGED on page 26 and Figure 20:
Operating mechanism section diagram
(drawout trip-free linkage shown)
mechanism CLOSED, closing spring
CHARGED on page 27.
The trip-free coupling rod (62.8) permits the
immediate de-coupling of the drive lever
(62.6) and the jack shaft (63.0) to override
the closing action by trip command or by
means of the racking interlocks.
The trip-free coupling rod (62.8) forms a
link between the drive lever (62.6) and the
jack shaft (63.0). The rigidity of this link
depends upon a spring-return latch carried
within the coupling rod.
The latch pivots within the coupling rod and
is normally positioned to maintain the
rigidity of the coupling rod.
Trip-free coupling link (62.8.2) and trip-free
coupling lever (62.8.3) cause the springreturn latch position to be dependent upon
the normal tripping components and the
racking interlock.
Thus, whenever a trip command is applied
or the circuit breaker is not in the fully
CONNECT or TEST position, the trip-free
coupling rod is no longer rigid, effectively
de-coupling the drive lever and jack shaft.
Under these conditions the vacuum
interrupter contacts cannot be closed.
Opening
If the circuit breaker is to be tripped locally,
the tripping spring (64.0) is released by
pressing the trip button (54.0). In the case
of an electrical command being given, the
shunt-trip coil 52T (54.1) unlatches the
tripping (opening) spring (64.0). The
tripping spring turns the jack shaft (63.0)
via lever (63.5); the sequence being similar
to that for closing.
Rapid auto-reclosing
Since the closing spring is automatically
recharged by the motor-operating
mechanism when the circuit breaker has
closed, the operating mechanism is capable
of an "open-close-open" duty cycle as
required for rapid auto-reclosing.
The circuit breaker is suitable for use in
applications with a rated reclosing-time
interval of 0.3 seconds, per ANSI/IEEE
C37.06-2009.
Manual operation
Electrically-operated vacuum circuit
breakers can be operated manually if the
control supply should fail.
Manually charging the closing spring
Refer to Figure 16: Use of manual-spring
operation crank on page 22. Insert the hand
crank (50.0) in hole (50.1) and turn it
clockwise (about 48 revolutions) until the
indicator (55.0) shows CHARGED. The hand
crank is coupled with the charging
mechanism via an over-running coupling;
thus the operator is not exposed to any risk
should the control supply be restored during
charging.
Manual closing
To close the circuit breaker, press the close
button (53.0). The OPEN/CLOSED indicator
(55.0) will then display CLOSED and the
closing-spring condition indicator (58.0) will
now read DISCHARGED.
Manual opening
The tripping spring is charged during
closing. To open the circuit breaker, press
the trip button (54.0) and OPEN will be
displayed by indicator (55).
23
Figure 17: Operating mechanism section diagram (drawout trip-free linkage shown) mechanism OPEN, closing spring DISCHARGED
62.5.1†
62.5
62.3†
62.1
50.3
62.2†
50.3.1
62.5.2†
53.0
64.5*
53.1
62.2.2
62.6
64.2.2
64.0*
62.8.1
64.2.1†
Charging flange
Driver
53.0
Close pushbutton
53.1
Close coil 52SRC
54.0
Open pushbutton
54.1
Trip coil 52T
62.1
Charging shaft
62.2
Crank
62.2.2
Closing-spring mounting
62.3
Cam disc
62.5
Lever
62.5.1
Pawl roller
62.5.2
Close latch pawl
62.6
Drive lever
62.8
Trip-free coupling rod
62.8.1
Spring-return latch
62.8.2
Trip-free coupling link (draw bar)
Trip-free coupling lever
62.8.2†
62.8.6
Interlock lever push rod
62.8*
62.8.7
Interlock lever actuator
62.8.8
Trip-free actuator
62.8.5†
64.5
63.0*
62.8.8
50.3
50.3.1
Push rod and cam assembly
63.5*
63.7
63.5
63.1
Insulating coupler
62.8.5
64.2*
48.0 63.5*
Description
48.0
62.8.3
54.0
62.8.3†
64.3.1*
Item
62.8.7†
62.8.6†
63.0
Jack shaft
63.1
Lever - phase C
63.5
Lever - phase B
63.7
Lever - phase A
64.0
Opening spring
64.2
Trip-latch pawl
64.2.1
Trip-latch pin
64.2.2
Latching pawl-release lever
64.3
Lever
64.3.1
Jack-shaft pawl
64.5
Opening-spring shaft
* Items moved from position shown in Figure 19: Operating mechanism section diagram (drawout trip-free linkage shown) mechanism
CLOSED, closing spring DISCHARGED on page 26 on trip operation.
† Items moved from position shown in Figure 18: Operating mechanism section diagram (drawout trip-free linkage shown) mechanism
OPEN, closing spring DISCHARGED on page 25 on closed spring discharge operation.
24
Figure 18: Operating mechanism section diagram (drawout trip-free linkage shown) mechanism OPEN, closing spring DISCHARGED
.
Item
Description
48.0
Insulating coupler
50.3
Charging flange
50.3.1
Driver
53.0
Close pushbutton
53.1
Close coil 52SRC
54.0
Open pushbutton
62.2†
50.3.1†
62.1†
54.1
Trip coil 52T
62.1
Charging shaft
50.3†
62.2
Crank
62.2.2
Closing-spring mounting
62.5†
62.5.1†
62.3
Cam disc
62.5
Lever
62.5.1
Pawl roller
62.5.2
Close latch pawl
62.6
Drive lever
62.8
Trip-free coupling rod
62.8.1
Spring-return latch
62.8.2
Trip-free coupling link (draw bar)
62.8.3
Trip-free coupling lever
62.8.5
Push rod and cam assembly
62.8.6
Interlock lever push rod
62.8.7
Interlock lever actuator
62.8.8
Trip-free actuator
63.0
Jack shaft
63.1
Lever - phase C
63.5
Lever - phase B
63.7
Lever - phase A
64.0
Opening spring
64.2
Trip-latch pawl
64.2.1
Trip-latch pin
64.2.2
Latching pawl-release lever
64.3
Lever
64.3.1
Jack-shaft pawl
64.5
Opening-spring shaft
62.3†
62.2.2†
64.5*
54.1*
62.8*
64.2*
64.3*
63.5*
63.0
64.5*
48.0
63.5*
63.7*
63.5*
63.1*
* Items moved from position shown in Figure 20: Operating mechanism section diagram (drawout trip-free linkage shown) mechanism
CLOSED, closing spring CHARGED on page 27 on trip operation.
† Items moved from position shown in Figure 17: Operating mechanism section diagram (drawout trip-free linkage shown) mechanism
OPEN, closing spring DISCHARGED on page 24 on closed spring discharge operation.
25
Figure 19: Operating mechanism section diagram (drawout trip-free linkage shown) mechanism CLOSED, closing spring DISCHARGED
62.5.1
62.5
62.1
62.2
62.5.2
62.3
53.0
64.5
Item
Description
48.0
Insulating coupler
53.0
Close pushbutton
53.1
Close coil 52SRC
62.1
Charging shaft
62.2
Crank
62.2.2
Closing-spring mounting
62.3
Cam disc
62.5
Lever
62.5.1
Pawl roller
62.5.2
Close latch pawl
62.6
Driver lever
62.8
Trip-free coupling rod
63.0
Jack shaft
63.1
Lever - phase C
63.5
Lever - phase B
63.7
Lever - phase A
64.5
Opening-spring shaft
62.6
53.1
62.2.2
62.8
64.5
63.7
63.5
63.1
48.0
63.0
63.5
* Numbered items moved from position shown in Figure 18: Operating mechanism section diagram (drawout trip-free linkage
shown) mechanism OPEN, closing spring DISCHARGED on page 25.
26
Figure 20: Operating mechanism section diagram (drawout trip-free linkage shown) mechanism CLOSED, closing spring CHARGED
Item
Description
50.3
Charging flange
50.3.1
Driver
62.1
Charging shaft
62.2
Crank
62.2.2
Closing-spring mounting
62.3
Cam disc
62.5
Lever
62.5.1
Pawl roller
62.2
50.3.1
62.1
62.5
62.3
50.3
62.5.1
62.2.2
*N
umbered items moved from position shown in Figure 19: Operating mechanism section diagram (drawout trip-free linkage shown)
mechanism CLOSED, closing spring DISCHARGED.
27
Figure 21: Operator sequential operation diagram
Closing
Closed
voltage applied.
Undervoltage device
27 picks up.
Anti-pumping feature (52Y) assures a continuously applied closing command does not cause
the circuit breaker to reclose automatically after it has tripped out on a fault.
Spring-charge motor
(88.0) energized.
Continuous
closing command.
Closing spring is
fully charged.
LS21 and LS22
operate to
de-energize springcharging motor.
No action! Open
52b in series with
close coil (52SRC)
blocks closing
spring-release.
L3 opens in series
with anti-pump
relay (52Y).
LS9 closes close
circuit only when
closing spring is
fully charged.
Circuit
Circuit
breaker
breaker
is closed.
is open.
Closing
command
when
Close coil is
actuated through
the closed 52b
contacts and the
two normally closed
Closing contacts of the antispring is pump relay (52Y).
not charged.
No action! Antipump relay (52Y)
picks up through
the closed LS3
contact and opens.
52a contacts in
series with the trip
coil (52T) close to
enable a trip
operation.
LS4 closes to signal
closing spring is
charged.
Circuit breaker
auxiliary contacts
52a and 52b change
state.
Trip coil (52T) can
only be activated
when in series
connected 52a
contact is closed.
Trip coil (52T)
unlatches the
opening spring.
The closing spring is
unlatched.
The opening spring
is charged.
The circuit breaker
closes.
LS21 and LS22 close
to energize motor
(88). LS3 closes and
LS4 opens to cancel
closing spring
signal.
The anti-pump relay
(52Y) opens two
contacts in series with
the close coil (52SRC).
The close coil (52SRC)
is now blocked and
cannot be activated
until springs are fullycharged and close
command is removed.
Footnote:
1.
Optional items.
Trip
command.
Undervoltage device (27) is
activated by opening a NC
contact in series with 27 or by
loss or reduction of tripping
voltage.1
Undervoltage device (27) is
activated by closing NO contact,
shorting the 27 coil. The NO
contact is only effective with the
circuit breaker closed. Resistor
required.1
Undervoltage device
27 unlatches the
opening spring.1
Circuit breaker trips.
28
Motor cutoff switches
LS21, LS22 and LS3 are
closed because the
closing spring is
discharged.
Before the springcharge motor has
recharged the closing
spring and opened LS3,
anti-pump relay (52Y)
picks up and seals in.
Rapid auto-reclosing. The closing spring is automatically recharged as described above.
Therefore, when the circuit breaker is closed both of its springs are charged. The closing
spring charges the opening spring during closing. As a result, the circuit breaker is capable of
an O-0.3s-CO-3 min-CO operating cycle. The dashed line shows the operating sequence
initiated by the closing command.
Tripping
Close coil (52SRC)
unlatches the closing
spring and the circuit
breaker closes.
Secondary shuntrelease (dual-trip)
function activated
by remote trip
command contact
NO.1
Secondary release
unlatches the
opening spring.1
Figure 22: Typical elementary diagram
(+)
01
T
01
C
SD16
SD13
W
21
LS21
22
41
42
SD3
Motor
13
14
DC supply
22
88
21
LS41
31
32
21
LS22
22
MI1
A1
22 A2
MI2 13
21
22
21
14
TB
1
2
3
4
5
6
SD15
R
G
52b
21
14
LS3
52Y
22
13
SD1
SD4
52Y
31
52Y
32
52SRC
A1
A2
24
52b
23
A1
52Y
SD14
52a
52T
A2
34
LS9
33
52a
SD2
(-)
SD11
54
55
SD9
64
52a
63
91
52a
SD12
92
SD7
101
52b
SD10
102
SD5
74
52b
73
SD8
84
52a
83
52a
111
112
121
52b
122
52b
SD6
Item
Description
Item
Description
88.0
Spring-charging motor
LS
Spring-charged switch
52a
Auxiliary switch is open when circuit breaker is open
M11, M12
Mechanical interlock
52b
Auxiliary switch is closed when circuit breaker is closed
OI/C
Control switch (close)
52SRC
Spring-release coil (close)
OI/T
Control switch (trip)
R
Red indicating light (closed)
W
White indicating light (spring charged)
52T
Shunt-trip coil
52Y
Closing relay (anti-pump)
G
Green indicating light (open)
Standard:
Fuses in close circuit. Slugs in trip circuit (fuses optional).
Shown with springs DISCHARGED, trip-latch reset, circuit breaker OPEN, circuit breaker in CONNECT or WITHDRAWN position.
29
Indirect releases (dual-trip or
undervoltage) (optional)
The indirect release provides for the
conversion of modest-control signals into
powerful mechanical-energy impulses. It is
primarily used to trip medium-voltage circuit
breakers while functioning as a secondary
(dual-trip) release or undervoltage-release
device.
33.0
23.0
27.0
25.0
31.0
21.0
11.0
13.0
7.0
1.0
9.0
15.0
6.0
3.0
Item
Description
Item
Description
1.0
Magnet core
15.0
Tripping pin
3.0
Housing
21.0
Locking pin
6.0
Mounting holes
23.0
Striker pin
7.0
Magnet coil
25.0
Latch
9.0
Magnet armature
27.0
Spring
11.0
Tension spring
31.0
Striker-pin spring
13.0
Adjusting screw (factory set) for 11.0
33.0
Terminal block
Figure 23: Construction of secondary shunt release (shown charged)
29.0
The undervoltage device may be used for
manual or relay tripping by employing a
contact in series with an undervoltagedevice holding coil.
27.0
21.0
Item
Description
Item
25.0
Latch
29.0
Undervoltage enable/disable setting screw (undervoltage only)
21.0
Locking pin
23.0
Striker pin
25.0
Latch
Description
Figure 24: Latch details (shown charged)
30
Secondary shunt release (optional) (54.2)
A secondary shunt release (second trip coil)
is used for electrical tripping of the circuit
breaker by protective relays or manualcontrol devices when more than one trip
coil is required. The second trip coil is
generally connected to a separate auxiliary
supply (dc or ac) from the control supply
used for the normal trip coil.
Undervoltage release (optional) (54.2)
The undervoltage release is used for
continuous monitoring of the trippingsupply voltage. If this supply voltage falls
excessively, the undervoltage release will
provide for automatic tripping of the circuit
breaker.
23.0
25.0
These releases are mechanical-energy
storage devices. Their internal springs are
charged as a consequence of the circuitbreaker mechanism operation. This energy
is released upon application or removal (as
appropriate) of applicable control voltages
(refer to Figure 23: Construction of
secondary shunt release (shown charged)
and Figure 24: Latch details (shown
charged) on page 30 and Figure 25:
Undervoltage lock/operate selection on
page 31).
Relay tripping may also be achieved by
employing a normally open contact in
parallel with the holding coil. If this scheme
is used, a resistor must be provided to limit
current when the normally open contact is
closed.
Secondary and undervoltage releases are
available for all standard ANSI/IEEE
control voltages.
Construction and mode of operation of
secondary release and undervoltage
release
Refer to Figure 23: Construction of
secondary shunt release (shown charged)
and Figure 24: Latch details (shown
charged) on page 30 and Figure 25:
Undervoltage lock/operate selection on
page 31.
The release consists of a spring powerstoring mechanism, a latching device and an
electromagnet. These elements are
accommodated side-by-side in a housing
(3.0), with a detachable cover and three
through-holes (5.0) for fastening screws.
The supply leads for the trip coil are
connected to a terminal block (33.0).
The energy-storing mechanism consists of
the striker pin (23.0) and its operating
spring (31.0), which is mostly located inside
the striker pin (23.0). When the spring is
compressed, the striker pin is held by a latch
(25.0), whose sloping face is forced against
the appropriately shaped striker pin (23.0)
by spring (27.0). The other end of the latch
(25.0) is supported by a partly-milled
locking pin (21.0) (refer to Figure 24: Latch
details (shown CHARGED) on page 30), that
pivots in the cover sheets of the magnet
armature (9.0). The armature (9.0) pivots in
front of the poles of the U-shaped magnet
core, (1.0) and is pulled away from it by the
tension spring (11.0).
If the magnet coil (7.0) of the shunt release
3AX1101 is energized by a trip signal, or if
the tripping pin (15.0) is mechanically
actuated, magnet armature (9.0) is swung
against the pole faces.
When this happens, the latch (25.0) loses its
support and releases the striker pin (23.0),
that is forced out by the spring (31.0).
Position A: locked (disabled)
29.0
A
23.0
B
Position B: unlocked (enabled) (operating position)
Item
Description
23.0
Striker pin
29.0
Undervoltage
enable/
disable
setting screw
A
23.0
B
29.0
Cancel the lock for the undervoltage release by shifting the locking screw (29)
from A (disable) to B (enable).
Figure 25: Undervoltage lock/operate selection
01
T
SD5
24
23
120 or 240 Vac
supply
52a
Capacitor
A1
(+)
52T
A2
34
On the undervoltage release 3AX1103, the
latch (25.0) is held by the locking pin (21.0)
as long as the armature (9.0) is attracted
(energized) (refer to Figure 21: Operator
sequential operation diagram on page 28).
If the circuit of the magnet coil (7.0) is
interrupted, the armature (9.0) drops off,
thus causing the latch (25) to lose its
support and release the striker pin (23).
33
52a
1
(-)
Resistor
2
(+)
Rectifier
(-)
Capacitor trip
Figure 26: Capacitor-trip device
31
Following every tripping operation, the
striker pin (23.0) must be reset to its normal
position by loading the spring (31). This
takes place automatically via the operating
mechanism of the circuit breaker.
Since the striker pin of the undervoltage
release 3AX1103 is latched only when the
armature is attracted, this trip is provided
with a screw (29.0) (refer to Figure 25:
Undervoltage lock/operate selection on
page 31).
This screw is provided to allow locking the
striker pin (23.0) in the normal position for
adjusting purposes or for carrying out trial
operations during circuit breaker servicing.
Position A (disabled or locked) disables the
undervoltage release. Position B is the
normal (enabled or operating) position.
Capacitor-trip device
The capacitor-trip device is an auxiliary
tripping option providing a short-term
means of storing adequate electrical energy
to ensure circuit breaker tripping.
Secondary disconnect
Signal and control power is delivered to the
internal circuits of the circuit breaker by an
arrangement of movable-contact fingers
(refer to Figure 27: Secondary disconnect on
the circuit breaker) mounted on the top of
the circuit breaker.
When the circuit breaker is racked into the
TEST or CONNECT position in the metal-clad
switchgear, these disconnect fingers engage
a mating-disconnect block on the inside of
the switchgear (refer to Figure 28:
Secondary disconnect inside the
switchgear). These electrical connections
automatically disengage when the circuit
breaker is racked from the TEST to the
DISCONNECT position.
All of the control power necessary to
operate the circuit breaker is connected to
this disconnect block inside the switchgear.
The external trip- and close- circuits and
associated circuits are also connected to the
same disconnect block.
This device is applied in circuit breaker
installations lacking independent auxiliarycontrol power or a station battery. In such
installations, control power is usually
derived from the primary source. In the
event of a primary-source fault, or
disturbance with resulting reduction of the
primary-source voltage, the capacitor-trip
device will provide short-term tripping
energy for circuit breaker opening due to
the protective relay operation.
The capacitor trip includes a rectifier to
convert the 120 or 240 Vac control voltage
to a dc voltage that is used to charge a large
capacitor to the peak of the convertedvoltage wave (refer to Figure 26: Capacitor
trip device on page 31).
Figure 27: Secondary disconnect on the circuit
breaker
Shock absorber
A type 38-3AH3 vacuum circuit breaker is
equipped with a sealed, oil-filled, viscous
damper or shock absorber (61.8) (refer to
Figure 15: Stored-energy operating
mechanism on page 20). The purpose of
this shock absorber is to limit overtravel and
rebound of the vacuum interrupter
movable-contacts during the conclusion of
an opening operation. The shock-absorber
action affects only the end of an opening
operation.
Figure 28: Secondary disconnect inside the
switchgear
32
Auxiliary switch
Figure 29: Auxiliary switch shows the circuit
breaker mounted auxiliary switch. This
switch provides auxiliary contacts for
control of circuit breaker closing and
tripping functions. Contacts are available for
use in relaying and external logic circuits.
This switch is driven by linkages connected
to the jack shaft.
As the circuit breaker is racked into the
appropriate position inside the switchgear,
the MOC-switch operating arm engages the
pantograph linkage (refer to Figure 33:
Circuit-breaker compartment on page 34).
Operation of the circuit breaker causes the
pantograph linkage to transfer motion to
the MOC switches located above the
pantograph.
The auxiliary switch contains both “b”
(normally closed) and “a” (normally open)
contacts. When the circuit breaker is OPEN,
the “b” switches are closed and the “a”
switches are open.
The "a" and "b" contacts can be used in
relaying and control-logic schemes.
Mechanism-operated cell (MOC)
switch (optional)
Figure 30: MOC switch operating arm on a
circuit breaker and Figure 31: MOC (bottom)
and TOC (top) switches and associated
terminal blocks show the principal
components that provide optional-control
flexibility when operating the circuit breaker
in the TEST (optional) and CONNECT
(standard) positions.
Figure 30: MOC switch operating arm on a
circuit breaker shows the MOC-switch
operating arm that projects from the right
side of the circuit breaker, above the bottom
rail structure. The MOC-switch operating
arm is part of the jack-shaft assembly and
directly reflects the OPEN or CLOSED
position of the circuit breaker primary
contacts.
A
B
All circuit breakers contain the MOC-switch
operating arm. However, MOC switches are
provided in the switchgear only when
specified.
Figure 29: Auxiliary switch
The circuit breaker engages the MOC switch
only in the CONNECT (operating) position
unless an optional TEST position pickup is
specified in the contract. If a TEST position
pickup is included, the circuit breaker will
engage the auxiliary switch in both
positions. Up to 24-stages may be provided.
Truck-operated cell (TOC) switch
Figure 31: MOC (bottom) and TOC (top)
switches and associated terminal blocks
shows the optional TOC switch. This switch
is operated by the circuit breaker as it is
racked into the CONNECT position.
Various combinations of "a" and "b" contacts
may be optionally specified. These switches
provide control and logic indication that a
circuit breaker in the cell has achieved the
CONNECT (ready-to-operate) position.
C
D
E
Item
Description
Item
Description
A
Rating interlock
D
Spring-dump interlock
B
Closed circuit breaker interlock
C
Trip-free interlock
E
Circuit breaker ground disconnect
Figure 32: Circuit-breaker interlocks and ground disconnect
Figure 30: MOC switch operating
arm on a circuit breaker
Figure 31: MOC (bottom) and TOC
(top) switches and associated terminal blocks
33
Figure 33: Circuit-breaker compartment
G
E
I
M
B D F
A
A
K
L
H
C
J
B D F
I
K
L
J
H
34
C
Item
Description
A
Shutter-operating linkage
B
Shutters
C
Racking mechanism padlock provisions
D
Primary disconnects (behind shutters)
E
MOC switch (optional)
F
Current transformers (behind barrier)
G
Secondary disconnect
H
Trip-free padlock provisions
I
Current-transformer barrier
J
Racking mechanism
K
Ground bar
L
Rating interlocks
M
MOC operating pantograph
Trip-free interlock
Figure 32: Circuit-breaker interlocks and
ground disconnect on page 33 shows the
devices providing the trip-free interlock
function. The purpose of the trip-free
interlock is to hold the circuit breaker
operating-mechanism mechanically and
electrically trip-free. The circuit breaker is
held trip-free during racking and whenever
the circuit breaker is between the TEST and
CONNECT positions within the switchgear
enclosure.
This interlock functions so that the circuit
breaker primary contacts can only be closed
when in the CONNECT position, in the TEST
position or out of the switchgear cell.
Rating interlock
Figure 32: Circuit-breaker interlocks and
ground disconnect on page 33 shows the
rating-interlock interference plates mounted
on the circuit- breaker frame. The circuitbreaker interference plates are
complemented by matching plates located
in the cubicle.
The interference plates (rating interlocks)
test the circuit-breaker voltage, continuous
current and interrupting and momentary
ratings and will not allow circuit breaker
insertion unless the circuit-breaker ratings
match or exceed the cell rating.
Circuit-breaker frame
The frame of the type 38-3AH3 vacuum
circuit breaker contains several important
devices and features deserving of special
attention. These are the ground disconnect,
the four racking wheels and the four
handling wheels.
Ground disconnect
Figure 32: Circuit-breaker interlocks and
ground disconnect on page 33 shows the
ground disconnect contact mounted at the
bottom of the circuit breaker. The springloaded fingers of the disconnect contact
engage the ground bar (refer to Figure 33:
Circuit-breaker compartment on page 34) at
the bottom of the switchgear assembly. The
ground bar is to the right of the racking
mechanism, shown at the bottom center of
the switchgear.
Circuit-breaker handling wheels
The type 38-3AH3 vacuum circuit breaker is
designed for easy movement into and out of
the metal-clad switchgear assembly. A
section of indoor or Shelter-Clad switchgear
does not require a transfer truck or lifting
truck for handling of the circuit breaker
when all circuit breakers are located at floor
level. Once the circuit breaker is racked out
of the switchgear, the unit can be pulled
using the handles on the front of the circuit
breaker. The circuit breaker will roll on its
bottom four wheels.
When circuit breakers are located above
floor level, handling of the circuit breakers
requires the use of a lifting device or a crane
with a lift sling.
Hazardous voltage and high-speed moving parts.
Will cause death, serious injury and property damage.
Do not by-pass interlocks or otherwise make interlocks inoperative.
Interlocks must be in operation at all times.
Read this instruction manual. Know and understand correct interlock
function. Check interlock function prior to inserting a circuit breaker into
a switchgear cubicle.
35
Racking mechanism
Figure 33: Circuit-breaker compartment on
page 34 shows the racking mechanism in
the switchgear used to move the circuit
breaker among the DISCONNECT, TEST and
CONNECT positions. This mechanism
contains a circuit-breaker racking-block that
mates with the bottom of the circuit-breaker
housing, and locks the circuit breaker to the
racking mechanism during in and out
movement.
A racking crank (refer to Figure 2: Type
38-3AH3 vacuum circuit breaker racking on
page 11) mates to the threaded squareshaft of the racking mechanism. Clockwise
rotation of the crank moves the circuit
breaker into the switchgear, and
counterclockwise rotation removes it.
The racking and trip-free interlocks provide
several essential functions.
hey prevent racking a CLOSED circuit
1. T
breaker into or out of the switchgear
assembly.
2. T
hey discharge the closing springs
whenever the circuit breaker is inserted
into or withdrawn from the switchgear.
3. T
hey prevent closing of the circuit
breaker unless it is in either the TEST or
CONNECT positions, and the racking
crank is not engaged.
The rating interlock prevents insertion of
a lower-rated circuit breaker into a cubicle
intended for a circuit breaker of higher
ratings.
Vehicle function and operational
interlocks
A type 38-3AH3 vacuum circuit breaker is
comprised mainly of the vacuum interrupter/
operator module fitted to a vehicle. This
vacuum interrupter/operator module is an
integral arrangement of operating
mechanism, dielectric system, vacuum
interrupters and means of connecting the
primary circuit. The vehicle supports the
vacuum interrupter/operator module,
providing mobility and fully coordinated
application in Siemens type GM38
switchgear.
Successful coordinated application of the
fully assembled type 38-3AH3 vacuum
circuit breaker is achieved through precise
alignment in fixtures during manufacture,
and important functional interlocking.
Alignment
All aspects of the circuit breaker structure
impacting alignment and interchangeability
are checked using master fixtures at the
factory. Field adjustment will not normally
be required.
Interlocks
Circuit breaker racking-interlocks
The vacuum interrupter/operator module,
the vehicle portion of the circuit breaker and
the racking mechanism in the switchgear all
cooperate to provide important operational
interlocking functions.
1. R
ating interlock
The rating interlock consisting of a
coded-interference plate is mounted on
the vehicle (refer to Figure 32: Circuitbreaker interlocks and ground disconnect
on page 33). A mating-interference
blocking plate is mounted in the drawout
compartment (refer to Figure 33: Circuitbreaker compartment on page 34).
The two plates are mounted in alignment
and must pass through each other in
order for the circuit-breaker vehicle to
enter the drawout compartment. The
interlock is coded to test rated voltage, as
well as interrupting and continuous
current ratings. The circuit breaker must
equal or exceed all of the cubicle ratings
in order to enter the compartment.
36
2. R
acking interlocks
A . CLOSED circuit breaker interlock
Figure 32: Circuit-breaker interlocks
and ground disconnect on page 33
shows the location of the CLOSED
circuit-breaker interlock-plunger on
the circuit-breaker frame.
The purpose of this interlock is to
positively block circuit-breaker
racking-operations whenever the
circuit breaker is CLOSED. The plunger
is coupled to the jack shaft as seen in
Figure 15: Stored-energy operating
mechanism, item 63 on page 20.
When the jack shaft rotates to close,
the interlock plunger is driven straight
downward beneath the frame of the
circuit breaker. The downward
projecting plunger blocks racking
operation when the circuit breaker is
CLOSED.
Figure 33: Circuit-breaker
compartment on page 34 shows the
racking mechanism located on the
floor in the center of the circuit
breaker compartment. Note the two
"wing-like" elements that project from
the left side of the racking
mechanism. The CLOSED circuit
breaker interlock plunger, when down
(circuit breaker CLOSED), falls behind
the front wing in the TEST position
and behind the rear wing in the
CONNECT position.
D
A
B
C
Item
Description
A
Trip-free mechanical-interlock switch
B
Trip-free interlock
C
Spring-dump interlock
D
Spring-dump tube
Figure 34: Interlock mechanisms on the type 38-3AH3 vacuum circuit breaker
The wings are coupled to the element
of the racking mechanism that
shrouds the racking screw. This shroud
must be moved rearward to insert the
racking-crank socket in order to
engage the racking shaft. With the
plunger down (circuit breaker
CLOSED), the wings and shroud
cannot be moved and thus racking is
blocked.
37
D
E
F
Item
Description
A
Enclosure rear
B
Trip-pushrod cam
C
Interlock levers
D
Close-latch lever
E
Closing spring-release cam
F
Normal operating position
G
Trip-pushrod cam
H
Trip-latch lever
I
Trip-free pushrod
J
Retaining rings
K
Spring-dump tube
G
A
H
I
The operation of the trip-free rackinginterlock may be seen in Figure 34:
Interlock mechanisms on the type
38-3AH3 vacuum circuit breaker on
page 37. As the spring-dump interlock
rises, it moves a series of linkages,
that cause a guided spring-dump tube
to rise, and enter the operatingmechanism enclosure.
Figure 35: CLOSED circuit breaker
interlock mechanism in stored-energy
mechanism shows the operating
mechanism detail components that
establish a trip-free condition as the
guided spring-dump tube rises. The
rising tube raises a lever attached to
the base of the operating-mechanism
enclosure. This lever raises the tripfree pushrod.
B
C
J
C
J
K
Figure 35: CLOSED circuit-breaker interlock mechanism in stored-energy mechanism
B. Trip-free interlock
Figure 32: Circuit-breaker interlocks
and ground disconnect on page 33
shows the trip-free interlock. This
interlock is a plunger with a roller on
the lower end. The plunger roller
tracks the shape of the cam profiles
on the racking mechanism in the
switchgear (refer to Figure 33: Circuitbreaker compartment on page 34).
38
The racking-cam profile on the racking
mechanism allows the trip-free
racking-interlock to be in the lowest
position (reset) only when the circuit
breaker is in the TEST or the CONNECT
position. Thus, during racking, the
trip-free interlock is held in an
elevated condition except when the
circuit breaker reaches the TEST or the
CONNECT position. The circuit breaker
can be closed only when the interlock
plunger is down, and will trip if the
plunger is moved up.
The rising trip-free pushrod elevates
the trip-free pushrod cam, that pushes
the trip-free coupling lever (62.8.3)
(refer to Figure 15: Stored-energy
operating mechanism on page 20)
toward the rear of the enclosure.
The movement of the trip-free
coupling lever toward the rear of the
enclosure is transmitted through the
trip-free coupling link (62.8.2) to the
spring-return latch (62.8.1). With the
latch displaced from a normal reset
position, the trip-free coupling rod
(62.8) cannot apply closing effort to
the jack shaft (63.0). Thus, upon
release, the closing-spring energy will
not be transmitted to the jack shaft.
C. Automatic
closing-spring energy
release
The automatic closing-spring energyrelease (spring-dump) (refer to Figure
32: Circuit-breaker interlocks and
ground disconnect on page 33) is a
plunger with a roller on the lower end.
The spring dump has a return spring
that returns the spring dump to the
reset or lowered position.
The plunger roller tracks the shape of
the spring discharge cam on the
racking mechanism in the switchgear
(refer to Figure 33: Circuit-breaker
compartment on page 34).
The spring-dump cam raises the
spring-dump interlock upon insertion
of the circuit breaker into the
compartment, or upon withdrawal
from the compartment. The interlock
is raised at about the time the front
wheels pass over the cubicle sill.
It allows the spring-dump interlock to
be in the reset (lowest) position at all
other times.
The operation of the spring-dump
interlock may be seen in Figure 34:
Interlock mechanisms on the type
38-3AH3 vacuum circuit breaker on
page 37. As the spring-dump interlock
rises, it causes the guided springdump tube to rise and enter the
operating-mechanism enclosure.
However, the trip-free interlock is
raised, so that the operating
mechanism is held trip-free (refer to
"Trip-free interlock" on page 33). Thus,
the energy in the closing springs is
released (spring-dump), without
movement of the jack shaft or the
vacuum-interrupter contacts.
D Trip-free
interlock position mechanical interlock
In order to prevent the motorcharging circuit from "making and
breaking" as the circuit breaker and
cubicle secondary disconnects make
or break physical contact, an electrical
switch is provided. This switch is
mounted in the line of action taken by
the trip-free interlock plunger that
follows the racking-mechanism cam
and is elevated at all times while the
circuit breaker is in the drawout
compartment except when in the TEST
or CONNECT positions.
A striker plate, integral with the tripfree interlock plunger, engages and
operates (opens) the switch when the
plunger is in an elevated position
blocking spring-charging motor
operation. The switch is closed when
the circuit breaker occupies the TEST
or CONNECT position, allowing the
charging motor to operate
automatically.
Figure 35: CLOSED circuit-breaker
interlock mechanism in stored-energy
mechanism shows the operating
mechanism detail components that
establish a spring-dump condition as
the tube rises. The rising tube raises a
lever attached to the base of the
operating-mechanism enclosure. This
lever raises the trip-free pushrod, that
elevates the closing-spring release
cam. The closing-spring release cam
moves the closing-spring latch, that
causes the closing springs to
discharge.
39
Maintenance
Hazardous voltage and high-speed moving parts.
Will cause death, serious injury and property damage.
Do not by-pass interlocks or otherwise make interlocks inoperative.
Interlocks must be in operation at all times.
Read instruction manuals, observe safety instructions and use qualified
personnel.
Introduction and maintenance intervals
Periodic inspections and maintenance are
essential to safe and reliable operation of
the type 38-3AH3 vacuum circuit breaker.
Regardless of the length of the maintenance
and lubrication interval, Siemens
recommends the circuit breaker should be
inspected and exercised annually.
When the type 38-3AH3 vacuum circuit
breaker is operated under "usual service
conditions," maintenance and lubrication is
recommended at ten-year intervals or at the
number of operations indicated in Table 2.
For the safety of maintenance personnel as
well as others who might be exposed to
hazards associated with maintenance
activities, the safety-related work practices
of NFPA 70E (especially chapters 1 and 2)
should always be followed when working on
electrical equipment.
"Usual" and "unusual" service conditions for
medium-voltage metal-clad switchgear are
defined in ANSI/IEEE C37.20.2, section 8.1
and C37.04, section 4 together with
C37.010, section 4. Generally, "usual service
conditions" are defined as an environment
where the equipment is not exposed to
excessive dust, acid fumes, damaging
chemicals, salt air, rapid or frequent
changes in temperature, vibration, high
humidity and extreme temperatures.
The definition of "usual service conditions"
is subject to a variety of interpretations.
Because of this, you are best served by
adjusting maintenance and lubrication
intervals based on your experience
with the equipment in the actual
service environment.
40
Maintenance personnel should be trained in
the safety practices, procedures and
requirements that pertain to their respective
job assignments.
This instruction manual should be reviewed
and retained in a location readily accessible
for reference during maintenance of this
equipment.
The user must establish a periodic
maintenance program to ensure trouble-free
and safe operation.
The frequency of inspection, periodic
cleaning and preventive-maintenance
schedule will depend upon the operation
conditions. NFPA Publication 70B, "Electrical
Equipment Maintenance" may be used as a
guide to establish such a program.
The use of unauthorized parts in the repair of the equipment, or tampering by unqualified personnel
can result in hazardous conditions, that can result in death, serious injury or property damage.
Follow all safety instructions contained herein.
Note: A preventive maintenance program is
not intended to cover reconditioning or
major repair, but should be designed to
reveal, if possible, the need for such actions
in time to prevent malfunctions during
operation.
Recommended hand tools
The type 38-3AH3 vacuum circuit breaker
uses both standard SAE (U.S. customary)
and metric fasteners. Metric fasteners are
used for the vacuum interrupters and in the
vacuum interrupter/operator module. SAE
(U.S. customary) fasteners are used in most
other locations. This list of hand tools
describes those normally used in
disassembly and re-assembly procedures.
Metric:
S
ockets and open-end wrenches:
7, 8, 10, 13, 16, 17, 18, 19 and 24 mm
Hex keys: 2, 5, 6, 8 and 10 mm
Deep sockets: 19 and 24 mm
Torque wrench: 0 - 150 Nm
(0 - 100 ft-lbs.).
SAE (U.S. customary):
S
ocket and open-end wrenches:
5/16, 3/8, 7/16, 1/2, 9/16, 11/16, 3/4 and
7/8 inches
Hex keys: 3/16 and 1/4 inches
S
crewdrivers: 0.032 x 1/4 inches wide
and 0.055 x 7/16 inches wide
Pliers
Light hammer
Dental mirror
Flashlight
Drift pins: 1/8, 3/16 and 1/4 inches
R
etaining-ring pliers (external type, tip
diameter 0.038 inches).
41
Failure to maintain the equipment can result in death, serious injury, property damage or product
failure, and can prevent successful functioning of connected apparatus.
The instructions contained herein should be carefully reviewed, understood and followed.
The maintenance tasks in Table 1 must be performed regularly.
Inspection items and tests
Primary-power path checks
C
leanliness check
Inspection of primary disconnects
Stored-energy operator-mechanism checks
Maintenance and lubrication
F
astener check
Manual spring-charging check
Contact-erosion check
Electrical-control checks
Wiring and terminals checks
Secondary-disconnect check
Automatic spring-charging check
Electrical close and trip check
Vacuum-integrity check
High-potential test
Insulation test
Contact-resistance test
Inspection and cleaning of circuit-breaker
insulation
Functional tests
Table 1: Maintenance tasks
42
Recommended maintenance and
lubrication
Periodic maintenance and lubrication should
include all the tasks shown in Table 1.
Recommended procedures for each of the
listed tasks are provided in this section of
the instruction manual.
The list of tasks in Table 1 does not
represent an exhaustive survey of
maintenance steps necessary to ensure safe
operation of the equipment.
Particular applications may require further
procedures. Should further information be
desired or should particular problems arise
not covered sufficiently for the user's
purposes, the matter should be referred to
Siemens at 1-800-347-6659 or 1-919-3652200 outside the U.S.
Removal from switchgear
Prior to performing any inspection or
maintenance checks or tests, the circuit
breaker must be removed from the
switchgear. The "Installation checks and
initial functional tests" section (refer to page
9) describes the removal procedure in detail.
The principal steps are repeated here for
information and guidance, but without the
details of the preceding section.
1. T
he first step is to de-energize the circuit
breaker. Figure 36: Trip-control
pushbutton (lower button) illustrates the
location of the trip control on the circuitbreaker operator panel. Depressing the
trip pushbutton opens the circuit breaker
prior to removal from the switchgear.
2. T
he second step in the removal
procedure is to de-energize control
power to the circuit breaker. Open the
control-power disconnect device.
ack the circuit breaker to the
3. R
DISCONNECT position.
erform the spring discharge check. This
4. P
is done by first depressing the red trip
pushbutton. Second, depress the black
close pushbutton. Third, depress the red
trip pushbutton again, and observe the
spring condition indicator. It should read
DISCHARGED.
5. R
emove the circuit breaker from the
switchgear. Refer to page 10 of
"Installation checks and initial functional
tests" section of this instruction manual
for special instructions and precautions
regarding removal of a circuit breaker not
at floor level.
6. T
he circuit breaker can be located either
on the floor or on a pallet. Each circuit
breaker has four wheels and handles to
allow one person to maneuver the unit
on a level surface without assistance.
Figure 36: Trip-control pushbutton (lower button)
Checks of the primary power path
The primary power path consists of three
vacuum interrupters and three upper- and
three lower-primary disconnects. These
components are checked for cleanliness and
condition. The vacuum interrupters are also
checked for vacuum integrity.
Some test engineers prefer to perform the
contact-erosion check during the manualspring charging check of the operator, since
charging of the springs is necessary to place
the contacts in the CLOSED position.
Also, the vacuum-integrity check is usually
performed in conjunction with the highpotential test.
These instructions follow the
recommendation these tests (contacterosion/manual-spring charging check and
vacuum integrity/high-potential tests)
should be combined as described.
Cleanliness check
Figure 37: Type 38-3AH3 vacuum circuit
breaker showing vacuum interrupters and
primary disconnects (outer-phase barrier
removed) is a side view of the type 38-3AH3
vacuum circuit breaker with the outerinsulating barriers removed to show the
vacuum interrupter and the upper- and
lower-primary disconnects.
All of these components must be cleaned
and free of dirt or any foreign objects. Use a
dry lint-free cloth. For stubborn dirt, use a
clean cloth saturated with isopropyl alcohol
(except on a vacuum interrupter).
For stubborn dirt on a vacuum interrupter,
use a cloth and warm water and a small
amount of mild liquid-household detergent
as a cleaning agent. Dry thoroughly using a
dry lint-free cloth.
Figure 37: Type 38-3AH3 vacuum
circuit breaker showing vacuum
interrupters and primary
disconnects (outer-phase barrier
removed)
43
Circuit breaker
type
Number of
years/closing
operations
(whichever
comes first)
38-3AH3
10 years/
10,000
operations
Table 2: Maintenance and lubrication schedule
Inspection of primary disconnects
Figure 38: Primary disconnect in mated
position shows the primary-disconnect
contact-fingers engaged. When the contacts
are mated with the switchgear primary-stud
assembly, there is forceful contact
distributed over a wide area. This maintains
low-current flow per individual contact
finger.
Inspect the contact fingers for any evidence
of burning or pitting that would indicate
weakness of the contact-finger springs.
Inspect the primary-disconnect arms for
physical integrity and absence of
mechanical damage.
Inspect the flexible connectors that connect
the bottom movable-contacts of the vacuum
interrupters to the lower primary-disconnect
arms for tightness and absence of
mechanical damage, burning or pitting.
Using a clean cloth saturated with isopropyl
alcohol, clean old lubricant from primary
disconnects, and apply a very thin layer of
Siemens contact lubricant (reference
15-172-791-233).
Maintenance and lubrication
Table 2 gives the recommended
maintenance intervals for circuit breakers.
These intervals assume the circuit breaker is
operated under “usual service conditions” as
discussed in ANSI/IEEE C37.20.2, section
8.1, and C37.04, section 4, together with
C37.010, section 4. The maintenance and
lubrication interval is the lesser of the
number of closing operations or the time
interval since last maintenance.
The vacuum-interrupter operator
mechanism is shown in Figure 39: Operator
mechanism lubrication on page 45, with the
front cover and the operator-control panel
removed to show construction details.
Both the tripping spring and the closing
spring are shown. The movable end of the
closing spring is connected to a crank arm.
The movable end of the opening spring is
connected to the jack shaft by a pull rod.
Clean the entire stored-energy operator
mechanism with a dry, lint-free cloth.
Check all components for evidence of
excessive wear.
Place special attention on the closing springcrank and the various pushrods and
linkages.
Figure 38: Primary disconnect in
mated position
Lubricate all non-electrical moving or sliding
surfaces with a light coat of synthetic grease
or oil.
Lubricants composed of ester oils and
lithium thickeners will generally be
compatible.
F
or all lubrication (except electrical
moving or sliding surfaces), use one of
the following:
Checks of the stored-energy operator
mechanism
The stored-energy operator checks are
divided into mechanical and electrical
checks for simplicity and better
organization. This first series of checks
determine if the basic mechanism is clean,
lubricated and operates smoothly without
control power. The contact-erosion check of
the vacuum interrupter is also performed
during these tasks.
44
lüber Isoflex Topas L32
K
(part 3AX11333H)
Klüber Isoflex Topas L32N (spray)
(part 15-172-879-201).
Source:
K
lüber Isoflex Topas L32 or L32N:
Klüber Lubrication North America L.P.
www.klueber.com.
Primary-disconnect contacts (multi-fingered
clusters) and secondary- disconnect
contacts (strips and fingers) are to be wiped
clean, and a film of Siemens contact
lubricant (15-172-791-233) applied. Avoid
getting contact lubricant on any insulating
materials.
Figure 39: Operator mechanism lubrication
Klüber L32 or Klüber L32N
Typical for all three-phases
45
Fastener check
Inspect all fasteners for tightness. Both
locknuts and retaining rings are used.
Replace any fasteners that appear to have
been frequently removed and replaced.
Manual-spring charging and contacterosion checks
Perform the manual-spring charging check
contained on page 12 in the section
"Installation check and initial functional
tests." The key steps of this procedure are
repeated here.
1. Insert the hand-charging crank into the
manual-charge socket at the front of the
operator control-panel. Turn the crank
clockwise (about 48 revolutions) to
charge the closing spring. Continue
cranking until the CHARGED flag appears
in the window of the spring-indicator.
Figure 40: Contact-erosion check
mark dot circled in orange (shown
with circuit breaker OPEN)
2. Press the close (black) pushbutton. The
contact-position indicator on the
operator-control panel should indicate
the circuit-breaker contacts are CLOSED.
3. Perform the contact-erosion check.
Contact erosion occurs when high-fault
currents are interrupted or when the
vacuum interrupter is nearing the limit of
its contact life. Determination of
acceptable contact condition is checked
by the visibility of the white-erosion
mark (refer to Figure 40: Contact-erosion
check mark dot circled in orange (shown
with circuit breaker OPEN)). The whiteerosion mark is located in the keyway (or
slot) on the movable stem of the vacuum
interrupter, near the plastic-guide
bushing.
The contact-erosion check procedure is:
A
. Be sure the circuit-breaker primary
contacts are CLOSED.
B
. O
bserve the white-erosion mark of
each pole (refer to Figure 36: Tripcontrol pushbutton (lower button) on
page 43). When this mark is visible,
contact wear is within acceptable
limits.
4. Press the red trip pushbutton after
completing the contact-erosion check.
Visually verify the DISCHARGED condition
of the closing springs and the circuitbreaker contacts are OPEN.
5. Press the black close pushbutton.
Nothing should happen. The manualspring check should demonstrate smooth
operation of the operating mechanism.
High-speed moving parts.
Can result in serious injury.
Tripping spring is charged. If trip latch is moved, the stored-energy
springs will discharge rapidly.
Stay clear of circuit breaker components subject to sudden, high-speed
movement.
46
Hazardous voltage and high-speed moving parts.
Will cause death, serious injury and property damage.
Read instruction manuals, observe safety instructions and use qualified
personnel.
Electrical-control checks
The electrical controls of the type 38-3AH3
vacuum circuit breaker should be checked
during inspection to verify absence of any
mechanical damage, and proper operation
of the automatic-spring charging and close
and trip circuits.
Unless otherwise noted, all of these tests
are performed without any control power
applied to the circuit breaker.
Wiring and terminals check
1. Physically check all of the circuit-breaker
wiring for evidence of abrasion, cuts,
burning or mechanical damage.
2. C
heck all terminals to be certain they are
solidly attached to their respective
device.
Secondary-disconnect check
In addition to checking the terminals of the
secondary disconnect, the secondary
contact fingers need to be free to move
without binding. Depress each finger,
confirm presence of spring force (contact
pressure) and verify freedom-of-motion.
Automatic spring-charging check (control
power required)
Repeat the automatic spring-charging check
described in "Installation checks and initial
functional tests" (refer to pages 12-13).
Primary tasks of this check are:
he circuit breaker is energized with
1. T
control power for this check.
2. De-energize the source of control power.
3. Install the circuit-breaker end of the splitplug jumper over the secondary
disconnect of the circuit breaker. The
split-plug jumper has one male and one
female connector and cannot be installed
incorrectly (refer to Figure 5: Split-plug
jumper connected to circuit breaker on
page 13).
4. Install the switchgear end of the splitplug jumper over the secondarydisconnect block inside the switchgear
(refer to Figure 6: Split-plug jumper
connected to switchgear on page 13).
5. Energize the control-power source.
hen control power is connected to the
6. W
circuit breaker, the closing springs should
automatically charge. Visually verify the
closing springs are CHARGED.
Note: A temporary source of control power
and test leads may be required if the
control-power source has not been
connected to the switchgear. When control
power is connected to the type 38-3AH3
vacuum circuit breaker, the closing springs
should automatically charge.
47
Figure 41: Typical vacuum interrupter contact curve
Note: Right-hand vertical segment of curve is located at the maximum symmetrical
interrupting current rating of the circuit breaker as shown in Table 12: Type 38-3AH3 vacuum
circuit breaker ratings (new "constant kA" ratings basis) on page 64 or Table 13: Type
38-3AH3 vacuum circuit breaker ratings (historic “constant MVA” ratings basis) on page 65.
Permissible operating-cycles
100,000
50,000
20,000
10,000
5,000
2,000
1,000
500
200
100
50
15 (21 kA)
18 (31.5 kA)
19 (40 kA)
20
100
40
50
31.5
20
21
25
10
5
2
1
10
Breaking current symmetrical
value
Vacuum interrupters, types VS-30030 and VS-30041
48
Electrical close and trip check
(control power required)
A check of the circuit-breaker control circuits
is performed while the unit is still connected
to the switchgear by the split-plug jumper.
This check is made with the circuit breaker
energized by control power from the
switchgear.
1. O
nce the circuit-breaker springs are
CHARGED, move the switchgearmounted close/trip switch to the CLOSE
position. There should be both the sound
of the circuit breaker closing and
indication the circuit-breaker contacts
are CLOSED by the main contact status
indicator.
s soon as the circuit breaker has closed,
2. A
the automatic spring-charging process is
repeated.
3. A
fter a satisfactory close operation is
verified, move the switchgear-mounted
close/trip switch to the TRIP position, or
send a trip command from a protective
relay. Verify by both sound and contact
position that the contacts are OPEN.
Completion of these checks
demonstrates satisfactory operation of
auxiliary switches, internal protective
relays and solenoids.
Vacuum-interrupter mechanical check
Refer to Figure 42: Lower pole support with
insulated coupler, Figure 43: Primary
contact CLOSED and insulated coupler
DISCONNECTED and Figure 44: CLOSED
primary contact forced OPEN by manual
pressure on page 49, Figure 45: Contactresistance test of the primary contacts on
page 52 and Figure 46: Vacuum interrupter
replacement illustration on page 56.
Before putting the circuit breaker into
service, or if a vacuum interrupter is
suspected of leaking as a result of
mechanical damage, perform a vacuumintegrity check either mechanically as
described in this section, or alternatively,
electrically using a high-potential test set as
described in the next section.
Open and isolate the circuit breaker and
detach the insulated coupler (48.0) from
lever (48.6) (refer to Figure 42: Lower pole
support with insulated coupler).
The atmospheric pressure will force the
moving contact of a hermetically-sealed
interrupter into the CLOSED position,
causing lever (48.6) to move into the
position shown in Figure 43: Primary
contact CLOSED and insulated coupler
DISCONNECTED.
Spring-charging motor checks
No additional checks of the spring-charging
motor are necessary.
A vacuum interrupter may be assumed to be
intact if it shows the following
characteristics:
Vacuum interrupter
The life expectancy of a vacuum interrupter
is a function of the number of interruptions
and magnitude of current interrupted.
1. A
n appreciable closing force has to be
overcome when lever (48.6) is moved to
the OPEN position by hand (refer to
Figure 44: CLOSED primary contact
forced OPEN by manual pressure).
A vacuum interrupter must also be replaced
at 10,000 mechanical operations or when
the contacts have been eroded beyond
allowed limits.
Vacuum interrupter replacement procedures
are detailed in the following maintenance
instructions.
The curve shown in Figure 41: Typical
vacuum interrupter contact curve on page
48 is offered as a guide to life expectancy.
48.0
48.6
Item
Description
48.0
Insulating coupler
48.6
Lever
Figure 42: Lower pole support with
insulated coupler
48.6
48.0
Item
Description
48.0
Insulating coupler
48.6
Lever
Figure 43: Primary contact CLOSED
and insulated coupler
DISCONNECTED
2. W
hen the lever is released, it must
automatically return to the CLOSED
position with an audible sound as the
contacts touch.
After vacuum-integrity check, reconnect the
lever (48.6) to the insulated coupler (48.0).
Figure 44: CLOSED primary contact
forced OPEN by manual pressure
49
High-potential tests employ hazardous voltages.
Will cause death and serious injury.
Follow safe procedures, exclude unnecessary personnel and use safety
barriers. Keep away from the circuit breaker during application of test
voltages. Disconnect the split plug jumper from between the circuit
breaker and switchgear before conducting high-potential tests.
Vacuum interrupters may emit X-ray radiation.
Can result in serious injury.
Keep personnel more than six feet away from a circuit breaker under
test.
X-rays can be produced when a high-voltage is placed across two circuit
elements in a vacuum.
High-potential tests
The next series of tests (vacuum integrity
and insulation) involve use of high-voltage
test equipment. The circuit breaker under
test should be inside a suitable test barrier
equipped with warning lights.
Vacuum-integrity check
(using dielectric test)
A high-potential test is used to verify
the vacuum integrity of the circuit breaker.
The test is conducted on the circuit breaker
with its primary contacts in the OPEN
position.
50
High-potential test voltages
The voltages for high-potential tests are
shown in Table 3: High-potential test
voltages on page 51.
Note: Do not use dc high-potential testers
incorporating half-wave rectification. These
devices produce high-peak voltages.
High-peak voltages will produce X-ray
radiation. DC testers producing excessive
peak-voltages also show erroneous readings
of leakage current when testing vacuum
circuit breakers.
Rated
maximum-voltage
Rated power-frequency
withstand
kV (rms)
kV (rms)
kV (rms)
kV dc
38.0
80
60
85
Vacuum-integrity test procedure
1. O
bserve safety precautions listed in the
DANGER and WARNING advisories.
Construct the proper barrier and warning
light system.
2. G
round the frame of the circuit breaker,
and ground each pole not under test.
3. A
pply test voltage across each pole for
one minute (circuit breaker OPEN).
4. If the pole sustains the test voltage for
that period, its vacuum integrity has
been verified.
Note: This test includes not only the
vacuum interrupter, but also the other
insulation components in parallel with the
vacuum interrupter. These include the
standoff insulators and the insulated drivelinks, as well as the insulating (tension)
struts between the upper and lower
vacuum-interrupter supports. If these
insulation components are contaminated or
defective, the test voltage will not be
sustained. If so, clean or replace the
affected components, and retest.
As-found insulation and contactresistance tests
As-found tests verify the integrity of the
circuit-breaker insulation system. Megger*
or insulation-resistance tests conducted on
equipment prior to installation provide a
basis of future comparison to detect
changes in the protection afforded by the
insulation system. A permanent record of
periodic as-found tests enables the
maintenance organization to determine
when corrective actions are required by
watching for significant deterioration in
insulation resistance, or increases in contact
resistance.
*Megger is a registered trademark of
Megger Group, Ltd.
Field-test voltage
Table 3: High-potential test voltages
Insulation and contact-resistance
test equipment
In addition to the high-potential test
equipment capable of test voltages as listed
in Table 3, the following equipment is
required:
A
C high-potential tester with test voltage
of 1,500 volts, 60 Hz
Test equipment for contact-resistance
tests.
Insulation and contact-resistance
test procedure
1. O
bserve safety precaution listed in the
DANGER and WARNING advisories for the
vacuum-integrity check tests.
2. C
lose the circuit breaker. Ground the
frame of the circuit breaker, and ground
each pole not under test. Use manual
charging, closing and tripping
procedures.
3. A
pply the proper ac or dc high-potential
test voltage as shown in Table 3 between
a primary conductor of the pole and
ground for one minute.
4. If no disruptive discharge occurs, the
insulation system is satisfactory.
5. A
fter test, ground both ends and the
center metal section of each vacuum
interrupter to dissipate any static charge.
isconnect the leads to the spring6. D
charging motor.
7. C
onnect all points of the secondary
disconnect with a shorting wire. Connect
the shorting wire to the high-potential
lead of the high-voltage tester and
ground the circuit-breaker housing.
Starting with zero volts, gradually
increase the test voltage to 1,500 volts
rms, 60 Hz. Maintain test voltage for one
minute.
8. If no disruptive discharge occurs, the
secondary-control insulation level is
satisfactory.
51
9. D
isconnect the shorting wire and
re-attach the leads to the spring-charging
motor.
10.Perform contact-resistance tests of the
primary contacts (refer to Figure 45:
Contact-resistance test of the primary
contacts). Contact resistance should not
exceed the values listed in Table 4:
Maximum contact resistance.
Inspection and cleaning of circuit-breaker
insulation
1. Perform the spring discharge check on
the circuit breaker after all control power
is removed. The spring discharge check
consists of:
A . Depressing the red trip pushbutton
B. D
epressing the black close
pushbutton, and
Figure 45: Contact-resistance test of the primary contacts
C. D
epressing again the red trip
pushbutton.
All of these controls are on the circuit
breaker front panel. Visually verify the
DISCHARGE condition of the springs.
Continuous current
rating (A)
Contact resistance
(micro-ohms)
1,200
35
2,000
30
3,000
30
Table 4: Maximum contact resistance
2. R
emove phase barriers as shown in
Figure 7: Circuit breaker primary
disconnects on page 13.
3. C
lean barriers and post insulators using a
clean cloth dipped in isopropyl alcohol.
4. Replace all barriers. Check all visible
fasteners again for condition
and tightness.
Note: Do not use any cleaning compounds
containing chlorinated hydrocarbons such
as trichlorethylene, perchlorethylene or
carbon tetrachloride. These compounds will
damage the phenylene ether copolymer
material used in the barriers and other
insulation on the circuit breaker.
Functional tests
Refer to the "Installation checks and
functional tests" section of this instruction
manual on pages 9 to 13. Functional tests
consist of performing at least three manual
spring-charging checks and three automatic
spring-charging checks. After these tests are
complete, and the springs fully discharged,
all fasteners and connections are checked
again for tightness and condition before
re-installing the circuit breaker into the metalclad switchgear.
52
Overhaul
High-potential tests employ hazardous voltages.
Will cause death, serious injury and property damage.
Read instruction manual. All work must be performed with the circuit
breaker completely de-energized and the springs discharged. Limit work
to qualified personnel.
Introduction
The following procedures along with the
troubleshooting charts at the end of this
section, provide maintenance personnel
with a guide to identifying and correcting
possible malfunctions of the type 38-3AH3
vacuum circuit breaker.
Circuit-breaker overhaul
Table 5 gives the recommended overhaul
schedule for a type 38-3AH3 vacuum circuit
breaker. These intervals assume that the
circuit breaker is operated under "usual
service conditions" as discussed in ANSI/IEEE
C37.20.2, section 8.1 and ANSI/IEEE C37.04,
section 4, and elaborated in ANSI/IEEE
C37.010, section 4.
When actual operating conditions are more
severe, overhaul periods should occur more
frequently. The counter on the front panel
of the circuit breaker records the number of
operations.
Replacement at overhaul
The following components are replaced
during an overhaul of the circuit breaker,
when required:
V
acuum interrupters as determined by
vacuum-integrity test, contact erosion or
after 10,000 operations
S
pring-release coil, 52SRC
S
hunt-trip coil, 52T
A
uxiliary switch
T
rip-free drive-bar mechanism.
When these parts are changed, locking
devices must also be removed and replaced.
These include lock washers, retaining rings,
retaining clips, spring pins, cotter pins, etc.
1. R
eplace vacuum interrupters,
instructions follow (refer to page 54).
pring-release coil (52SRC) or shunt- trip
2. S
coil (52T).
A . R
emove two "push on" terminal
connections
Table 5: Overhaul schedule
Circuit breaker type
Number of closings
38-3AH3
10,000
B. R
emove two M4 hex-head screws and
dismount solenoid.
C. Install replacement solenoids with
two M4 hex-head screws and new
lock washers.
53
D. Solenoid mounting screws must be
installed using thread locking
adhesive (Loctite #222, Siemens part
15-133-281-007) and primer (Loctite
primer T, Siemens part
15-133-281-005).
E. Connect wires to coils with new
"push on" wire terminals (Siemens
part 15-171-600-002).
3. L ubricate operating mechanism in
accordance with instructions that follow.
4. When work is finished, operate circuit
breaker, close/open several times,and
check that all screw connections are
tight.
Vacuum interrupter replacement
It is recommended that vacuum interrupters
be replaced only by a qualified Siemens
representative. The information in the
following sections is provided to aid in
understanding the replacement procedures.
Replacement vacuum interrupters are
furnished as a complete assembly, and have
been completely tested and mechanically
conditioned.
It is recommended one vacuum interrupter
be removed and replaced completely rather
than removing two or more vacuum
interrupters at a time.
The following procedure describes the
procedure for removing and replacing a
vacuum interrupter. Components may be
identified by referencing Figure 46: Vacuum
interrupter replacement illustration on page
56 and Figure 47: Illustration showing
required technique for fastening terminalclamp hardware on page 57.
Note: Special care needs to be exercised in
removal or installation of hardware around
the bottom, or movable contact end, of the
vacuum interrupter.
The movable contact uses a metal bellows
to maintain the vacuum seal while still
permitting up and down motion of the
contact. This metal bellows is rugged and
reliable, and is designed to withstand years
of vertical movement. However, care should
be exercised to avoid subjecting the metal
bellows to excessive torque during removal
and replacement. Twisting the metal
bellows through careless bolt removal or
tightening may damage the vacuum
interrupter.
1.0 Removing the vacuum interrupter
1.1 Before starting work, the circuit breaker
should be isolated from all primary- and
control-power sources and all stored
energy discharged by tripping, closing
and tripping the circuit breaker by
hand. Discharge any static charge by
grounding both ends and the center
metal section of the vacuum
interrupter. Carefully remove outerphase and inter-phase barriers.
1.2 Loosen the lateral bolt(s) on terminal
clamp (29.2). Refer to Figure 47:
Illustration showing required technique
for fastening terminal-clamp hardware
on page 57 and employ the illustrated
procedure to loosen clamp hardware (6
or 8 mm hex-key and 13 or 16 mm
socket).
1.3 W
ithdraw pin (48.5) from insulating
coupler (48.0) and levers (48.6).
1.4 Remove coupling pin from the eye bolt
(36.3).
1.5 Free struts (28.0) from the upper polesupport (20.0). Loosen the strut
hardware on the lower support (40.0)
and swing the struts forward and
downward (16 mm open-end wrench
and 16 mm socket).
1.6 L oosen screws that secure the centering
ring (28.1) (10 mm open-end wrench).
54
1.7 R
emove bolt (31.2), lock washer and
large washer at stationary contact of
the vacuum interrupter (24 mm socket
with extension). Carefully note location
of the conductive spacer between
vacuum interrupter and pole support.
This spacer has a concave surface that
must be handled with care to avoid
damage.
1.8 Using a deep 24 mm socket with an
extension, loosen and remove the hexcap screw fastening the upper polesupport to the post insulator.
Completely remove the upper polesupport and set aside.
1.9 Grasp the vacuum interrupter (30.0)
and withdraw vertically upward.
Assistance may be required to spread
the clamp and work the terminal clamp
off the movable stem of the vacuum
interrupter. FORCIBLE TWISTING EFFORT
IS NOT ALLOWED. If the terminal clamp
cannot be easily removed, STOP!, check
to be certain hardware is loose and the
clamp is not binding.
2.0 Installing a vacuum interrupter
Note: Replacement vacuum interrupter
(30.0) will be received from the factory with
an eye bolt (36.3) in place, adjusted and
torqued to specific requirements. DO NOT
ALTER THE ADAPTER (eye-bolt) SETTING.
2.1 Inspect all silver-plated connection
surfaces for cleanliness. Clean only with
a cloth and solvent. Do not abrade, as
this will damage the silver plating.
2.2 Insert vacuum interrupter (30.0) in the
lower pole-support (40.0) with the
vacuum-interrupter label facing away
from the mechanism housing. Slip
terminal clamp (29.2) into position on
the movable stem.
2.3 Install the conductive spacer between
the fixed (upper) terminal of the
vacuum interrupter (30.0) and the
upper pole-support (20.0), with the
concave side of the spacer facing the
vacuum interrupter. Align vacuum
interrupter and fasten finger-tight using
heavy flat-washer, lock washer and nut
(31.2).
2.4 F
asten the upper pole-support to the
post insulator using finger pressure
only using hex-head (M16) bolt, lock
washer and flat washer.
2.5 A
ttach struts (28.0) to the upper polesupport (20) and replace hardware
(M10), but do not tighten at this time.
2.6 C
ouple levers (48.6) and drive link
(48.9) to the eye bolt (36.3), using the
pin supplied. Apply retention clips.
Appropriate pin is modestly chamfered,
not to be confused with pin for the
insulated coupler.
2.7 R
aise terminal clamp (29.2) against the
spacer (29.3) on the movable terminal
of the vacuum interrupter (36.1) and
position the vacuum interrupter (30.0)
so that its groove faces the connecting
surface of flexible strap (29.1). Refer to
Figure 47: Illustration showing required
technique for fastening terminal-clamp
hardware on page 57 and employ the
technique illustrated to fasten the
terminal clamp. Note opposing
wrenches. Tighten the bolt(s) of the
terminal clamp to a torque of 40 Nm
(30 ft-lb), taking care to see that the
terminal of the vacuum interrupter is
not subjected to excessive bending
movement.
Note: Excessive bending movement exerted
while fastening the terminal clamp will
damage the vacuum interrupter.
2.8 A
lign pole support (20.0) correctly and
tighten bolt fastening it to the post
insulator. Fasten securely all bolts
associated with struts (28.0).
2.9 T
ighten upper fastening bolt (31.2) on
the upper pole-support (20.0) holding
the vacuum interrupter firmly by its
upper insulator and operate levers
(48.6) by hand to see whether the
movable contact moves freely. If any
binding or lack of freedom is noted,
loosen bolt (31.2) and adjust the
vacuum interrupter in pole support by
turning the vacuum interrupter and
moving it slightly. Torque M16 bolt to
91-101 ft-lb (123-137 Nm).
55
Figure 46: Vacuum interrupter replacement illustration
20.0
31.2
28.0
30.0
28.1
29.3
36.1
29.2
29.1
36.3
40.0
56
48.9
48.6
48.5
48.0
Item
Description
20.0
Upper pole-support (pole head)
28.0
Strut
28.1
Centering ring
29.1
Flexible connector
29.2
Terminal clamp
29.3
Spacer (or shoulder)
30.0
Vacuum interrupter
31.2
Upper terminal bolt
36.1
Moving terminal
36.3
Eye bolt (or adapter)
40.0
Lower pole-support
48.0
Insulating coupler
48.5
Pin
48.6
Angled lever
48.9
Drive link
Figure 47: Illustration showing required technique for fastening terminal-clamp hardware
Item
Description
A
Moving contact (36.1)
B
Spacer (shoulder) (29.3)
C
Torque wrench
D
Direction of force (P)
E
Terminal clamp (29.2)
F
Holding wrench
G
Vacuum interrupter
G
F
A
B
D
E
C
D
Position of torque wrench to avoid undue stressing of moving contact (36.1)
2.10 The centering ring (28.1) has been
loose and floating during installation
of the vacuum interrupter. Check that
the movable contact is free to move
vertically without binding, and then
tighten the hardware that secures the
centering ring. Re-check that the
movable contact is free to move
vertically without binding.
2.11 Attach insulating coupler (48.0) and
lever (48.6) together, using pin (48.5).
Apply retaining clips. Correct pin has
ends that have been generously
chamfered.
2.12 Open and close circuit breaker several
times and then check to see that all
bolted joints and devices are tight.
3.0 C
hecking the contact stroke.
3.1 Open the circuit breaker.
3.2 F
ree insulating coupler (48.0) by
removing pin (48.5). The vacuum
interrupter contacts must now close
automatically as a consequence of
atmospheric pressure.
3.3 O
bserve the terminal clamp (29.2)
through the openings on each side of
the lower pole support (40.0).
U
sing vernier calipers measure the
distance from the bottom surface of
the terminal clamp to the bottom edge
of the cutout opening. Measure
carefully and record your result.
3.4 C
onnect the insulating coupler (48.0)
using pin (48.5) and the retaining clips
provided.
57
3.5 R
epeat the measurement described in
step 3.3 again with care to maximize
accuracy. Record your result.
3.6 Determine difference between the
measurements made under steps 3.3
and 3.5. Your result should be 18 mm
to 22 mm (0.709" to 0.866 ").
3.7 If you fail to achieve the listed results,
carefully repeat the entire procedure
making certain of your measurements.
3.8 Loosen locking nut on eye bolt on
insulated coupler (48.0), and retain
position of the eye. Make adjustments
in one-half turn increments. After
adjustment is completed, tighten eyebolt locking nut to 26-34 ft-lb (35 to
45 Nm).
4.0 After eye bolt is tightened to proper
torque, repeat all measurement
procedures, making certain they are in
agreement with values indicated in step
3.6.
5.0 Complete all other maintenance
procedures. Completely reassembled
circuit breaker should pass highpotential test before it is ready for
service.
58
Hydraulic shock absorber
The type 38-3AH3 mechanism is equipped
with hydraulic shock-absorber and a stop
bar that functions when the circuit breaker
opens (refer to Figure 15: Stored-energy
operating mechanism on page 20). The
shock absorber (61.8) should require no
adjustment. However, at maintenance
checks, the shock absorber should be
examined for evidence of leaking. If
evidence of fluid leakage is found, the shock
absorber must be replaced to prevent
damage to the vacuum-interrupter bellows.
Maintenance and
troubleshooting
Table 6: Periodic maintenance and lubrication tasks
Sub-assembly
Item
Inspect for
1. C
leanliness.
Vacuum interrupter
3. V
acuum integrity.
Note: Perform with high-potential tests.
Primary power path
Primary disconnects
Vacuum interrupter contact resistance
Cleanliness
Fasteners
Vacuum interrupter operator mechanism
Manual-spring check
Lubrication
Wiring
Electrical controls
Terminals and connectors
Close and trip solenoids, anti-pump relay,
auxiliary switches and secondary disconnect
High-potential test
2. C
ontact erosion.
Note: Perform with manual-spring checks.
Primary circuit-to-ground and between primary
disconnects
Control circuit-to-ground
1. B
urnt or damaged fingers.
2. L ubrication of contact surfaces.
1. R
ecord contact resistance with contacts
CLOSED and check at each maintenance
interval to monitor condition.
1. D
irt or foreign material.
1. T
ightness of nuts and other locking devices.
1. S
mooth operation of manual charging,
manual closing and manual tripping.
1. E
vidence of excessive wear.
2. L ubricaion of wear points.
1. M
echanical damage or abrasion.
1. T
ightness and absence of mechanical
damage.
1. A
utomatic charging.
lose and trip with control power.
2. C
1. 6
0-second withstand 60 kV, 60 Hz
(85 kV dc).
1. 6
0-second withstand 1.5 kV, 60 Hz.
1. C
leanliness.
Insulation
Barrier and all insulating components
2. C
racking, crazing, tracking or other sign of
deterioration.
59
Table 7: Troubleshooting
Problem
Symptoms
Possible causes and remedies
1. S
econdary control circuit is de-energized or
control circuit fuses are blown. Check and
energize or replace if necessary.
2. S
econdary disconnect contacts 15 or 16 are
not engaging. Check and replace if required.
3. D
amage to wiring, terminals or connectors.
Check and repair as necessary.
Closing spring will not automatically charge.
4. F
ailure of charging motor (88.0). Replace if
required.
5. M
otor cut-off switch LS21 or LS22 fails to
operate. Replace if necessary.
6. M
echanical failure of operating mechanism.
Check and contact regional service centers,
the factory or telephone Siemens field service
at 1-800-347-6659 or 1-919-365-2200 outside
the U.S.
1. Secondary control circuit de-energized or
control circuit fuses blown. Correct as
indicated.
2. N
o closing signal to secondary disconnect pin
13. Check for continuity and correct protective
relay logic.
Circuit breaker fails to close.
3. Secondary disconnect contacts 13 or 15 are
not engaging. Check and correct as required.
Closing springs charge,
but circuit breaker does
not close.
Closing coil or solenoid
(52SRC) fails to
energize. No sound of
circuit breaker closing.
4. Failure of anti-pump relay (52Y) contacts 21 to
22, 31 to 32 or 13 to 14. Check and replace as
required.
5. Failure of close coil (solenoid) (52SRC). Check
and replace as required.
6. Auxiliary switch NC contacts 41 to 42 are open
when circuit breaker contacts are open. Check
linkage and switch. Replace or adjust as
necessary.
7. Spring-charged switch LS9 NO contacts remain
open after springs are charged. Check and
replace as required.
Closing coil energizes.
Sound of circuit breaker
closing is heard but
circuit breaker contacts
do not close.
60
1. M
echanical failure of operating mechanism.
Check and contact regional service centers,
the factory or telephone Siemens field service
at 1-800-347-6659 or 1-919-365-2200 outside
the U.S.
Table 7: Troubleshooting (continued)
Problem
Symptoms
Electrical problem
Nuisance or false close
Mechanical problem
Possible causes and remedies
1. N
uisance or false closing signal to secondary
disconnect 13. Check protective relay logic.
Correct as required.
2. Closing coil (52SRC) terminal A2 is shortedto-ground. Check to determine if problems
are in wiring or coil. Correct as required.
1. M
echanical failure of operating mechanism.
Check and contact regional service centers,
the factory or telephone Siemens field
service at 1-800-347-6659 or 1-919-3652200 outside the U.S.
1. S
econdary control power is de-energized or
control power fuses are blown. Correct as
indicated.
2. Damage to wiring, terminals or connectors.
Check and repair as necessary.
Tripping coil or solenoid (52T) does not
energize. There is no tripping sound.
3. No tripping signal to secondary disconnect
contact 1. Check for continuity and correct
protective relay logic.
econdary disconnect contacts 1 or 2 are
4. S
not engaging. Check and replace if required.
5. F
ailure of trip coil (52T). Check and replace
if necessary.
6. Auxiliary switch NO contacts 23 to 24 or 33
to 34 are OPEN when circuit breaker is
CLOSED. Check linkage and switch. Replace
or adjust as necessary.
Circuit breaker will not trip
Tripping coil (52T) energizes. No tripping sound
is heard, and circuit breaker contacts do not
open. In other words, they remain CLOSED.
Tripping coil (52T) energizes. Tripping sound is
heard, but circuit breaker contacts do not open.
1. Failure of tripping spring or its mechanical
linkage. Check and replace if required.
echanical failure of operating mechanism.
1. M
Check and contact regional service centers,
the factory or telephone Siemens field
service at 1-800-347-6659 or 1-919-3652200 outside the U.S.
2. O
ne or more of the vacuum interrupters are
held CLOSED. Check and replace as
necessary.
Electrical problem
1. Tripping signal remains energized on
secondary-disconnect contact.
2. Check for improper protective relay logic.
Nuisance or false trip
Mechanical problem
1. M
echanical failure of operating mechanism.
Check and contact regional service centers,
the factory or telephone Siemens field
service at 1-800-347-6659 or 1-919-3652200 outside the U.S.
61
Appendix
Table 8: Circuit breaker control data
Footnotes:
1.
Current at nominal voltage
2.
Capacitor trip
3.
Value preceding slash (/) is the
current for the standard trip coil
with standard rating interrupting
time. Value following (/) is
current for optional trip coil with
three-cycle interrupting time.
4.
---- means this selection is not
available.
Control voltages, ANSI/IEEE C37.06
Spring charging motor
Close coil
Trip coil
Range
Nominal
Run
(Average)1
Inrush
(Peak)
Charging
Close
Trip
A1
A1
A
A
Seconds
48 Vdc
36 - 56
28 - 56
2.9
11.4/303
8
25
10
125 Vdc
100 - 140
70 - 140
1.0
4.8/7.43
4
18
10
250 Vdc
200 - 280
140 - 280
0.5
4.2/9.63
2
10
10
120 Vac
104 - 127
----4
0.9
----2, 4
6
----4
10
240 Vac
208 - 254
----4
0.4
----2, 4
3
----4
10
Table 9: Interrupting capacity auxiliary switch contacts2
Footnotes:
Two contacts in series
2.
All switch contacts are nonconvertible.
1.
Type switch
Continuous
current
Noninductive
A
120 Vac
240 Vac
48 Vdc
125 Vdc
250 Vdc
Circuit
breaker
10
10
5
10/301
9.6
4.8
TOC
15
15
10
0.5
0.5
0.2
MOC
20
15
10
10
10
5
Circuit
breaker
10
6
3
10
6
3
TOC
15
15
10
0.5
0.5
0.2
MOC
20
15
10
10
10
5
Control circuit voltage
Inductive
62
Table 10: Type 38-3AH3 vacuum circuit breaker weight in lbs (kg)1, 2, 3
Continuous current
Circuit breaker type
A
38-3AH3-31
38-3AH3-40
38-3AH3-1500
1,200
800 (364)
850 (387)
800 (364)
2,000
900 (409)
950 (432)
900 (409)
3,000
1,000 (455)
1,050 (478)
1,000 (455)
Footnotes:
1.
Weight estimates are for circuit
breaker only. Add 125 lbs (57 kg)
for packaging.
2.
Weight and dimensions are
approximate..
3.
Approximate circuit breaker
dimensions in inches (mm) (W x
D x H):
Net 44" (1,117 mm) x 46"
(1,168 mm) x 51" (1,294 mm)
Packed for shipment separate
from switchgear: 48" (1,218
mm) x 48" (1,218 mm) x 60"
(1,522 mm).
Table 11: Circuit breaker operating times (type 3AH3 operator)
Spring charging time
≤ 10 s
Close time from energizing close coil at rated control voltage to
contact touch (last pole)
Opening time from
energization trip coil at rated
control voltage to contact part
(last pole), not including
arcing time
38 kV
≤ 70 ms
5-cycle interrupting time (83 ms)
38 kV
≤ 56 ms
3.5-cycle interrupting time (58 ms)
38 kV
≤ 43 ms
3-cycle interrupting time (50 ms)
38 kV
≤ 38 ms
63
Table 12: Type 38-3AH3 vacuum circuit breaker ratings (new "constant kA" ratings basis)
Circuit breaker type1
Parameter
Rated voltage
Insulation levels
Rated values
Rated current
Current
Related
required
capabilities
Closing and
latching
(momentary)
Units
38-3AH3-31xxxx-82
38-3AH3-40xxxx-104
Maximum design voltage (V)2
kV rms
38.0
38.0
Voltage range factor (K)3
----
1.0
1.0
Power frequency
kV rms
80
80
Lightning impulse (BIL)
kV peak
150
150
Continuous4
A rms
1,200, 2,000,
3,000FC
1,200, 2,000,
3,000FC
Short circuit (at rated maximum design voltage) (I)5, 6
kA rms sym
31.5
40
Interrupting time7
cycles/ms
5/83
5/83
Withstand voltage
levels
Permissible tripping delay (Y)
Sec
2
2
Rated maximum design voltage (V) divided by K = (V/K)
kV rms
38.0
38.0
Maximum symmetrical interrupting (K x I)
kA rms sym
31.5
40
%dc component
%
47
47
Short-time current (K x I) (3 seconds)
kA rms sym
31.5
40
Asymmetrical (1.55 x I)
kA rms
49
62
Peak (2.6 x I)
kA peak
82
104
These ratings are in accordance with:
ANSI/IEEE C37.04-1999 Standard Rating
Structure for AC High-Voltage Circuit
Breakers
ANSI/IEEE C37.06-2009 AC High-Voltage
Circuit Breakers Rated on a Symmetrical
Current Basis - Preferred Ratings and
Related Required Capabilities
ANSI/IEEE C37.09-1999 Standard Test
Procedure for AC High-Voltage Circuit
Breakers Rated on a Symmetrical Current
Basis
ANSI/IEEE C37.010-1999 Application
Guide for AC High-Voltage Circuit
Breakers Rated on a Symmetrical Current
Basis.
64
Footnotes:
"xxxx" in type designation refers to the continuous
current rating 1,200, 2,000 or 3,000 A, as
appropriate. The 3,000 A fan-cooled rating is
achieved using fan cooling as indicated in
Footnote 4.
2.
Maximum design voltage the circuit breaker is
designed for and the upper limit for operation.
3.
K is listed for informational purposes only. For
circuit breakers rated on a "constant kA basis," the
voltage range factor is 1.0.
4.
3000FC indicates fan cooling is included in the
switchgear structure for this rating. 3000 A rating
is not available in outdoor equipment.
5.
All values apply to polyphase and line-to-line
faults.
6.
Standard duty cycle is O - 0.3s - CO - 3 min. - CO.
7.
Three-cycle (50 ms) interrupting is optionally
available.
1.
Table 13: Type 38-3AH3 vacuum circuit breaker ratings (historic "constant MVA" ratings basis)
Parameter
Nominal voltage class
MVA
1500
kV rms
38.0
----
1.65
Power-frequency
kV rms
80
Lightning-impulse (BIL)
kV peak
150
A rms
1,200, 2,000, 3,000FC
kA rms sym
21
cycles/ms
5/83
Sec
2
Rated maximum design voltage (V) divided by K = (V/K)
kV rms
23.0
Maximum symmetrical interrupting (K x I)7
kA rms sym
35
Short-time current (K x I) (3 seconds)
kA rms sym
35
Asymmetrical (1.6 x I)8
kA rms
56
Peak (2.7 x I)8
kA peak
95
Nominal three-phase MVA class
Maximum design voltage (V)
9
2
Voltage range factor (K)3
Withstand
voltage levels
Continuous4
Rated
current
Short-circuit (at rated maximum design voltage) (I)5, 6, 10
Interrupting time
11
Permissible tripping delay (Y)
Related
required
capabilities
Current
38-3AH3-1500-xxxx-95
34.5
Rated
voltage
Rated values
Circuit breaker type1
kV
General
Insulation levels
Units
Closing and
latching
(momentary)
These ratings are in accordance with:
ANSI/IEEE C37.04-1979 Standard Rating
Structure for AC High-Voltage Circuit
Breakers Rated on a Symmetrical Current
Basis
ANSI C37.06-1987 AC High-Voltage
Circuit Breakers Rated on a Symmetrical
Current Basis - Preferred Ratings and
Related Required Capabilities
ANSI/IEEE C37.09-1979 Standard Test
Procedure for AC High-Voltage Circuit
Breakers Rated on a Symmetrical Current
Basis
ANSI/IEEE C37.010-1979 Application
Guide for AC High-Voltage Circuit
Breakers Rated on a Symmetrical Current
Basis.
Footnotes:
“xxxx” in type designation refers to the continuous
current rating 1,200, 2,000, or 3,000 A, as
appropriate. The 3,000A fan-cooled rating is
achieved using fan cooling as indicated in
Footnote 4.
2.
Maximum design voltage the circuit breaker is
designed for and the upper limit for operation.
3.
K is the ratio of the rated maximum design voltage
to the lower limit of the range of operating voltage
in which the required symmetrical and
asymmetrical interrupting capabilities vary in
inverse proportion to the operating voltage.
4.
3000FC indicates fan cooling is included in the
switchgear structure for this rating. 3000 A rating
is not available in outdoor equipment.
5.
To obtain the required symmetrical interrupting
capability of a circuit breaker at an operating
voltage between 1/K times rated maximum design
voltage and rated maximum design voltage, the
following formula shall be used: Required
Symmetrical Interrupting Capability = Rated ShortCircuit Current (I) x [(Rated Maximum Design
Voltage)/(Operating voltage)].
For operating voltages below 1/K times maximum
design voltage, the required symmetrical
interrupting capability of the circuit breaker shall
be equal to K times rated short-circuit current.
6.
Within the limitations stated in ANSI/IEEE C37.041979, all values apply to polyphase and line-to-line
faults. For single phase-to-ground faults, the
specific conditions stated in clause 5.10.2.3 of
ANSI/IEEE C37.04-1979.
1.
Current values in this row are not
to be exceeded even for operating
voltage below 1/K times rated
maximum design voltage. For
operating voltages between rated
maximum design voltage and 1/K
times rated maximum design
voltage, follow Footnote 5.
8.
Current values in this row are
independent of operating voltage
up to and including rated
maximum voltage.
9.
"Nominal three-phase MVA class"
is included for reference only. This
information is not listed in ANSI/
IEEE C37.06-1987.
10.
Standard duty cycle is CO - 15s
- CO.
11.
Three-cycle (50 ms) interrupting
is optionally available.
7.
65
Table 14: Remarks
66
Table 14: Remarks (continued)
67
The information provided in this
document contains merely general
descriptions or characteristics of
performance which in case of actual use
do not always apply as described or which
may change as a result of further
development of the products. An
obligation to provide the respective
characteristics shall only exist if expressly
agreed in the terms of contract.
All product designations may be
trademarks or product names of Siemens
AG or supplier companies whose use by
third parties for their own purposes could
violate the rights of the owners.
Siemens Industry, Inc.
7000 Siemens Road
Wendell, NC 27591
For more information, contact:
1-800-347-6659
www.usa.siemens.com/mvswitchgear
Subject to change without
prior notice.
Order No.:
E50001-F710-A238-V3-4A00
All rights reserved.
Printed in USA
© 2013 Siemens Industry, Inc.
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement