The Linear Heat Sensing Cable comprises a warped pair twin core cable. Each core is of passivated steel and has a special heat reactive polymer insulation. The cable has an overall protective jacket Sheath. The primary mechanism of heat (Fire) Detection is that inner core insulating polymer is specially formulated such that is plasticises at a specific temperature. The cable is constructed such that the warped steel cores are in tension, and at the polymer trigger temperature the conductors connect. This provides an alarm signal to any associated monitoring device. However in most fire alarm installations the minimum requirement is that the LHS circuit is monitored for disconnections by means of an End Of Line (EOL) device and an appropriate Fire Alarm Channel or Address Loop Interface Unit.
Linear Heat Sensing Cable is versatile in that it can both provide an alternative to point heat detectors win conventional (space) protection situations and it may also be readily installed in very close proximity to monitor hazards. The detector is particularly suited to applications where harsh environmental conditions preclude the use of other forms of detection in areas that have access restrictions due to either physical difficulties or personnel health risks.
The module is designed to Monitor a length of Digital Linear Heat Sensing Cable (LHSC) for both fire condition, and Fault status (open circuit). The unit is designed such that it may be configured to operate in a ‘two wire’ mode that emulates the operation of conventional smoke & heat detectors. The unit may therefore be directly interfaced with Fire Control Panel by connection to fire zone trigger circuits or addressable interface modules. The unit has a 3 Digit LCD which activates on fire conditioned displays the distance into the zone that the alarm has occurred. Digital LHDC may be employed in lengths less than 2Km (1999m). The unit has an adjustment to accommodate interposing cables
Operable from two wire fire panel Trigger Circuits. Line/Low Power. Analog addressable loop interface - Loop Powered. Display of Alarm Location - Distance in meters. Fault monitoring of LHDC for open circuit conditions. LED indication of fire, Fault & supply status. Test & reset push-buttons. Volt free contact outputs for Fire & Fault conditions - Optional.
The unit is operated in conjunction with a length of Digital Linear Heat Sensing Cable (LHSC) and an End OF Line (EOL) terminator. The LHSC is a twisted pair twin core cable. When the trigger temperature of the LHSC is reached these cores connect and a Fire alarm is registered. The unit automatically determines the distance to the point of operation and displays this by means of an LCD.
The LHDC can be provided in a variety of constructional configurations that will meet the requirements of both standard and special applications. Two of the most commonly employed types are defined in the following table.
|Size - Oval
Min / Max
|700-070||60°C||70°C||45°C||3.5 - 4.5 mm||Nylon||Black||Orange / Blue|
|700-090||80°C||90°C||70°C||3.5 - 4.5 mm||Nylon||Nylon||Red / White|