Analog cable senses temperature variations by continuously monitoring the resistance of specially doped Negative Temperature Coefficient (N.T.C.) polymeric insulation.

A change in temperature produces a relative change in resistance between the two loops within the sensor cable – as temperature increases, resistance is lowered.

This change is monitored by an LHS control unit, which actuates an alarm signal at a pre-determined level. The integrating effect of the sensor cable enables it to detect either a hot spot or a lower level of temperature increase over its total length.

Linear Heat Detection System
Provided the sensor cable has not been directly subjected to temperatures greater than 120°C for excessive periods, it will recover to an alert condition after activating an alarm. Upon destruction, the cable fails permanently into the alarm state.

Benefits
• Flexible in installation
• Recoverable after operation
• Monitors precise point of risk
• Sensitive to small temperature variations
• Mechanical/environmental protection options

Applications
• Rack storage
• Escalators
• Cable trays
• Conveyors
• Floating roof tanks
• Covered car parks

At one end of the sensor cable, the four conductors are connected to an LHS control unit (optionally via a junction box). At the outer end, the conductors are joined and hermetically sealed to form two loops. Both loops are continuously monitored for open and short circuit faults. A breakage or disconnection of either loop initiates a fault signal in the control unit. Extra mechanical or environmental protection can be provided by the addition of a nylon coating or bronze braiding.