Linear Heat Detection (LHD) is a continuous heat detector in the form of a cable. It can detect heat at any points along its entire length. It is composed of Linear Heat Sensing Cable (LHSC), adapter unit and termination unit. The digital LHSC is composed of two twisted shield conductors insulated with a heat sensitive material, then wrapped with a protective tape and finished with an outer jacket. The heat sensitive material will soften and fuse at specific fixed temperature which causes the contact of the conductors, the short circuit will trigger an alarm to the Fire Alarm Control Panel (FACP), thus realize the function of fire detection and warning. Adapter unit is used to display and output fire alarm and fault signal.