LHD - Pertronic

Linear Heat Detection Cable (LHD)
Linear Heat Detection Cable (LHD) is designed for use where
traditional point Heat detectors are unsuitable. LHD is a fixed
temperature sensor capable of initiating an Alarm once its rated
temperature has been exceeded. LHD consists of two tri-metallic
conductors twisted together to keep them under mechanical
tension. Each conductor is individually coated in advanced,
temperature sensitive polymer that detects Heat conditions
anywhere along its length.
It is not required that a specific length be heated in order to
initiate an Alarm and therefore provides the advantage of line
coverage with point sensitivity.
 Suitable for use with Pertronic NZS4512-2010 conventional
zones of Loop Responder, Apartment Module, F16e, F4 and
 Simple installation, uses standard 10kΩ EOL resistor and one
Alarm resistor (RS) in series with the LHD cable.
 Can be used for Hazardous areas with Galvanic Isolator and
Pertronic Galvanic Isolator Interface
 Four temperature ranges:
NZS4512-2010 – Red
NZS4512-2010 – Yellow
NZS4512-2010 – Green
NZS4512-2010 – Green (High)
 Protective Outer Coating:
PVC stocked
- Nylon available by indent
 International Approvals:
CE marked, RoHS compliant, UL, FM, GOST-R
 Available:
200m and 500m drums
 Maximum Zone Length:
Typical Applications:
Industry Sectors: Tunnels, Mining, Manufacturing, Warehousing, Cold Stores, Communications and
General Industry, etc.
Industry Applications: Cable Trays, Conveyor Belts, Rack Storage, Floating Roof Storage Tanks, Area
Protection, Cool Store and Freezer to -40oC, Hazardous Areas.
Wire Overall Diameter
Minimum Bend Radius
Ambient Temperature:
Dual insulated, twisted pair of tri-metallic cores
1kV tested protective outer coat
50mm @ >0°C
100mm @ ≤0°C
-40°C to 45°C
- for 68°C or 78°C activating
-40°C to 70°C
- for 88°C or 105°C activating
30Vac / 42Vdc
Maximum Voltage Rating:
Colour of Outer
Installation Specifications:
Leader Cable: an approved type of cable, preferably Fire Rated, should be used between the Fire Alarm
Panel and the Linear Heat Detector cable.
A secure waterproof (IP66/67) junction box must be used to connect the Leader cable to the LHD cable.
Detection Cable: a very important factor when determining which rating of LHD cable to use is the
maximum ambient temperature the cable will be exposed to. To provide the fastest Alarm response with
minimum possibility of nuisance Alarms, the LHD cable with the lowest action temperature above the
maximum ambient temperature should be selected.
Maximum Ambient Temperature
≤ 45oC
45 C ≤ 70oC
Pertronic Industries Ltd
Available Action Temperatures
68oC or 78oC
88oC or 105oC
Linear Heat Detection (LHD) Installation Note, Iss 1.1, 201211
Guide Lines for Linear Heat Detection Cable Installation:
Important Do’s and Don’ts - please read thoroughly before commencing work
Installation of Linear Heat Detection Cable to conform to NZS4512-2010 and AS/NZS3000
Ensure the maximum ambient temperature of the selected detection cable will not be exceeded during storage or
normal operating conditions
Support the detection cable at 1m to 1.5m intervals
Ensure Linear Heat Detection Cable bend radius is:
50mm minimum for ambient = warm (>0°C)
100mm minimum for ambient = cold (≤0°C)
Ensure the detection cable is not in contact with any material, which may conduct heat onto the cable directly
A neoprene insulator or equivalent should be placed between the fixing clip and heat sensing cable
Ensure cable glands used are tightened to form a secure and moisture proof seal around the detection cable
Use appropriate junction boxes (or other approved method) to house Linear Heat Detection Cable connections
To avoid damage to the cable, use a drum reel when drawing LHD cable from the drum.
Avoid allowing the detection cable to come into contact with any materials which may act as a heat sink. This may
delay the activation of the cable in alarm situations
Do not perform the installation work at temperatures below -10°C
Do not exceed the maximum voltage of the detection cable (48Vdc or 32Vac)
Do not connect two lengths of detection cable which have different activation temperatures
Χ Do not connect lengths of fixed temperature cable in ‘T’ connections or Spurs
Χ Do not paint the detection cable
Χ Do not place the detection cable under excessive tension
Χ Do not bend the cable at right angles, the minimum bend radius is 50mm or 100mm as applicable
Χ Avoid subjecting the detection cable to mechanical damage which could result in false activation
Χ Avoid laying the detection cable in areas where heavy traffic may result in the cable being crushed
Χ Do NOT solder Linear Heat Detection cable
Installation Hardware:
cable supports should be placed every 1m and no more than 1.5m apart to support LHD cable and prevent
sagging. Extra supports may be necessary around corners and other transition areas.
Care should be taken when mounting the cable in clips (or equivalent) to ensure they do not crush the cable.
The LHD should be held firmly, but without deformation. Avoid placing excessive tension on the cable, NO
GREATER than 50N. Ensure that the minimum bend radius (50mm in normal temperatures, 100mm below
0oC) is observed at all times.
It is particularly important to use a neoprene insulator between the LHD cable and the fixing clip if the metal
clip is exposed to the sun or attached to equipment which may get hot and transfer heat to the cable.
Where possible, install LHD cable in one continuous run of cable with as few splices as practical.
Use a reel stand when pulling the LHD cable from a reel. DO NOT pull the cable off the reel vertically with
the reel stationary as this may twist and damage the cable. A wire guide (Catenary cable) may be required
for installations where supporting the cable at the recommended spacing is not practical. Ensure the
diameter or gauge of the catenary wire is adequate for the distance being spanned. 2mm stainless steel wire
is generally suitable.
Connections into junction boxes and other enclosures must use strain relief connectors which provide dust
and moisture protection (IP65 or greater). The standard diameter of LHD cable is 3.6mm to 4.5mm.
‘L’ Brackets: suitable for general support of cable, with various sizes, position and fixing holes available
‘V’ Clips: for use on cable trays. Use a neoprene insulator when clipping the detection cable into the clip
Other Support Brackets: are available for use in a wide variety of applications
Note: Pertronic Industries supplies LHD cable only, not the boxes, brackets or clips which should be obtained
from an electrical wholesaler.
Typical System Configuration
LHD Cable Spacing:
Maximum Distance
from Wall/Partition
1.0 to 1.5m
10m > 20m
1.0 to 1.5m
Minimum Distance
LHD Spacing
Below Ceiling
Support Spacing
Refer to NZS4512-2010, Section 405.5
1.0 to 1.5m
Refer to NZS4512-2010, Section 405.3.2 and Appendices C & D for further information.
Pertronic Industries Ltd
Linear Heat Detection (LHD) Installation Note, Iss 1.1, 201211
Basic Circuit:
The following Table can be used to select the Series Resistor (RS) value:
Conventional Circuit : 2003/2010
Loop Responder : FW >v3.00
Apartment Module : all versions
RS (Heat Mode)
RS (Smoke Mode)
RS = 100Ω
F16e : all versions
= 0m to 300m
RS = 330Ω
F16 : FW >v7.0
LHD = 0m to 3000m
F4 : FW >v2.26
F1 : FW >v2.3
Galvanic Isolator behind
Galvanic Isolator Interface
To operate in Heat mode, LHD length is limited to 300m.
If this cable length is exceeded, the circuit may operate in Smoke Mode, therefore the
outputs should be configured as for Heat mode operation
1) Selection of the Series Resistor (RS) determines whether activation of the LHD cable causes the
conventional circuit to operate within the Heat or Smoke band.
Because LHD cable functions as a Heat detector, it is important that the subsequent configuration of the
conventional circuit produces the Alarm outputs required of a Heat detector.
Operation of the LHD within the Smoke band is provided to allow lengths of LHD greater than 300m to be
used or with a length of LHD less than 300m and a value for the Series Resistor (RS) less than 100Ω, to
allow Smoke detectors to be installed on the Leader cable where desired.
Configuring the LHD to activate the Fire Alarm System correctly is the responsibility of the engineer.
2) If required, smoke detectors may be installed on standard Zone Leader cable only, not on the Linear Heat
Detection cable.
3) Linear Heat Detection cable must be continuous from RS to REOL, though lengths of similarly rated LHD
cable may be spliced together in series to extend the length of the detection system.
4) Contact Pertronic Technical Support for assistance calculating the maximum length of LHD if more than
300m is required in Heat mode.
Connecting LHD Cable
Always use terminal blocks to connect LHD cable as the heat generated while soldering can damage the
heat sensitive insulation.
Pertronic Industries Ltd
Linear Heat Detection (LHD) Installation Note, Iss 1.1, 201211
Splicing LHD Cable
If the fixed LHD cable is damaged or has triggered, remove the damaged section plus 3m either side.
Preferred method: use a junction box with screw terminals to make the join
Alternative method: splice two ends of detection cable together using a connection box and seal the splice
using sealant tape. Care should be taken to ensure the two core conductors do not contact each other at any
point and that the final spliced joint is secure and waterproof.
Low Temperature Installation:
Fixed temperature LHD cable may be used in ambient environments down to -40°C (eg. cold storage
warehouses, outdoors, etc.). Do not proceed when the ambient temperature is below -10°C, because the
cable may become less flexible and so prone to damage during installation.
The cable can shrink in length by 12% at -40°C, so if the temperature is likely to drop significantly after
installation, cable shrinkage must be taken into account when attaching support brackets.
To reduce the heat sink effect of the clip and avoid damage to the cable, place a neoprene insulator around
the cable before clipping it into the support bracket.
Increase the minimum bend of the detection cable to 100mm to account for the reduced flexibility. The
maximum distance between support brackets should not exceed 1m and it is important to support the cable
close to either side of any bend. Ensure any junction boxes or other enclosures are waterproof and suitable
for the expected operating environment.
Hazardous Area Installation:
LHD cable is suitable for Hazardous areas when interfaced with a Galvanic Isolator and Pertronic Galvanic
Isolator Interface.
Commissioning and Maintenance:
After installation and during routine maintenance, check the system to ensure the LHD cable is not damaged
and functions as expected.
 verify that the LHD cable is free of damage to the outer or inner insulation.
 inspect all support brackets and other aspects of the physical installation are appropriate.
 ensure neoprene insulators are correctly installed around the cable clips.
 verify that the cable cannot be damaged due to activity in the area of installation.
 check all joints, sealant and insulation tape are secure. Apply new sealant or tape, where required.
 perform electrical tests to determine the circuit created is functioning correctly:
 remove the conductors from the Fire Alarm Panel and measure the resistance across them.
 the resistance value should equal the End of Line resistance (10kΩ) plus approximately 100Ω/km for
each leg of the cable (200Ω/km for the length of the cable).
 record this value for later reference.
 test the system in-circuit with the Fire Alarm Panel by reattaching the LHD cable:
 short out the EOL resistor to activate an Alarm
 disconnect either leg from the EOL resistor to activate a Defect.
Functional Testing:
If a functional test is required, use a left over section of the LHD cable installed.
 Attach a short section (1m) of cable between the end of the LHD cable run and the EOL resistor.
 Using a suitable device, heat the length of test cable.
 Once the action temperature (including tolerances) has been reached, the system should Alarm.
 Use the panel’s manual to verify correct operation
 Ensure the length of Test cable is removed before placing the system back into operation.
Pertronic Industries Ltd
Linear Heat Detection (LHD) Installation Note, Iss 1.1, 201211
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