柴油发电机短路电流计算及有关保护问题

Short-circuit Current Calculation and Relevant Protection of Diesel Generator

指出民用建筑中柴油发电机作为应急或备用电源,由于其短路容量有限,短路电流的周期分量及非周期分量都会衰减,同时大量的电动机负荷,也会向短路点反馈电流。针对工程实际,对发电机与电动机的短路电流分别计算,衰减时间常数分别考虑,短路电流为二者算术和,并算出常用规格发电机出口处三相短路电流值。根据计算的短路电流,校核保护电器的短路分断能力和短路接通能力,以及线路保护选择性配合的问题。

As an emergency or stand -by power supply for civil buildings, diesel generator has a limited short - circuit capacity, so both the periodic component and non- periodic component of short-circuit current will be attenuated, and a large number of motor loads will also provide current to the short- circuit point. According to the actuality of the engineering, short -circuit currents of generator and motor are calculated respectively, which the attenuation time constant is eonsided respectively. The short- circuit is arithmetic sum of them. The 3- phase short- circuit values at the outlet of common specification generators are also calcuted. According to the computed results of the short- circuit current, short- circuit breaking capacity and short- circuit making capacity of the protective devices, and the selective coordination for the line protection are checked.