火灾条件下消防负载断路器性能研究

针对目前配电箱开关在火灾热影响下由于脱扣机构动作引起跳闸,不能保证消防设备供电问题,经过对消防配电箱的火灾试验研究,分析了外部热源对开关动作的影响。通过线损量的计算,得出了火灾情况下环境温度与电阻热损耗的关系。并依据双金属片热弯曲理论,推导出热脱扣机构动作力与端部位移成正比的关系。总结出消防终端设备开关热过载保护应仅用于动作信号而不应切断电源的结论。对于现有消防配电柜,给出了通过调整开关热脱扣机构倾斜角,来增加消防负荷的供电时间的方案,可以为消防供电系统断路器的可靠性设计作参考。

Study on Performance of Load Circuit Breaker for Fire-fighting under Fire

Releasing action of distribution box's switches caused by heat-affection in fire will lead to tripping,thus power supply for fire equipment can't be guaranteed.To analyze how external heat source affects the action of switches,a fire experiment was conducted on a full-scale distribution box.The relation between ambient temperature in fire and the heat loss of line resistance was firstly gotten by the calculation of line loss.Then,according to thermal bending theory of bimetals,it was deduced that the releasing force of thermal tripping mechanism kept direct proportion to end displacement,from which it is summarized that thermal overload protection for terminal fire equipment switches should be only used for action signals,but not for the cut of power supply.As for the existing fire distribution box with the same problem,it is suggested to increase the length of power supply for fire-fighting by adjusting the slope angle of thermal tripping mechanism.This study can provide references for the reliability design of the circuit breakers in power supply system for fire-fighting.