Abstract: In order to explore the influence of the sensitivity of the fire detector on the fire response of the cable trench and to verify the accuracy of the fire monitoring system, four types of fires: point temperature detectors, point smoke detectors, cable temperature detectors and suction smoke detectors were applied. A full-scale cable fire test was carried out in the standard substation cable trench fire compartment to test the fire alarm sequence of fire detectors with different sensitivities. Finally, according to the actual size of the cable trench, the FDS was used to build a numerical simulation model to simulate two different fire scenarios of open flame and smoldering, and the temperature field, toxic gas mass concentration and fire alarm sequence of fire detectors with different sensitivities are analyzed. The experimental results show that the average fire response time of cable temperature detectors, suction smoke detectors and point smoke detectors in substation cable trench fire detection are 41.2, 111.4 and 331.8 s respectively. The sensitivity of the detector has a great influence on the detection result, and its fire alarm response time is about 50% delayed compared with the cable-type linear temperature detector.

Key words: cable trench fire, fire detector, substation, fire response, sensitivity