叶　充(广州市设计院，广州市 510620)

Discussion on Calculation and Test of Earth Fault Loop Impedance of TN - S System

YE Chong(Guangzhou Design Institute,Guangzhou 510620,China)

Abstract：There are multiple similar but not identical formulas for calculating the maximum allowable cable length in the calculation and test of earth fault loop impedance of TN - S system at present. Different formulas and different coefficient values will lead to different results. While analyzing the appropriate values of different parameters in these formulas and the errors caused by different values,some suggestions are put forward for the verification of earth fault protection.

Key words：earth fault;loop impedance;TN - S system;maximum allowable cable length;relative error;electric shock;earth fault protection;general calculation method

摘　要：针对目前TN - S系统接地故障环路阻抗计算和测试中有几种相似但不完全相同的最大允许电缆长度计算公式，不同公式和不同系数取值会得出不同结果的情况，在分析这些公式中不同参数的合适取值和不同取值引起误差的同时，对接地故障保护校验提出建议。

关键词：接地故障；环路阻抗；TN - S系统；最大允许电缆长度；相对误差;电击；接地故障保护；通用计算法

中图分类号：TU852　　　　　文献标识码：A

doi：10.3969 / j. issn.1003－8493.2020.06.002