消防应急照明配电设计细节探讨

新国标《消防应急照明和疏散指示系统技术标准》实施后，配电距离较长的消防应急照明线路，存在末端电压降过大或计算值偏保守以及末端短路电流过小等问题。针对末端电压降过大或计算值偏保守问题，基于电压降计算公式，提出了一种新的实用计算方法，可以精确计算线路的电压降；针对线路末端短路电流过小问题，基于熔断器的熔断时间—电流特性曲线，提出了可以在规定时间内熔断的最小短路电流概念，计算出了安全电压下常用导线的极限供电距离。解决了电压降简化计算误差过大问题，提出了一种应急照明线路短路电流的便捷计算方法，可有效减少消防应急照明配电设计在此方面存在的安全隐患。

Discussion on the details of fire emergency lighting distribution design

After the implementation of the new national standard technical standard for fire emergency lighting and evacuation indication system, the fire emergency lighting lines with long distribution distance have some problems, such as excessive terminal voltage drop or conservative calculation value,and small short circuit current at the end, etc. Aiming at the terminal voltage drop is too large or the calculated value is conservative,a new practical calculation method that the voltage drop of the line can be calculated accurately was proposed. Aiming at the problem that the short circuit current at the end of the line is too small, based on the fusing time curve to current characteristics of the fuse, the concept of minimum short circuit current which can be fused in a specified time was proposed, and the limit power supply distance of common conductors under safe voltage was calculated. The problem of large error in simplified calculation of voltage drop was solved. A convenient calculation method for short circuit current of emergency lighting circuit was proposed. It can reduce the hidden danger of fire emergency lighting distribution design effectively in this respect.