配电网用户设备接地-接零保护混用风险分析

Risk analysis of grounding and zero protection mixed of user equipment of the distribution network

我国低压配电网接地形式普遍采用TT系统,而在人口密度较大的城镇地区普遍采用TN-C-S系统。针对低压配电网人身触电事故频发和漏保频跳的现象,课题组在福建部分地区对采用TT系统和TN-C-S系统区域展开调研,发现用户侧设备保护接线不规范,同一台区的用户设备存在不接保护线、保护接地与保护接零混用的现象。本文对TT系统、TN-C-S系统中在单相接地故障、相线碰壳、“断零”3种情况下对设备接地-接零保护混用存在的安全风险进行分析,这对现场规范设备保护接线具有实践指导意义。

The TT system is generally used in the grounding form of low-voltage distribution network in China,and the TN-C-S system is widely used in urban areas with large population density.Aiming at the phenomenon of frequent electric shock accidents and residual current operated protective device frequency tripping in low-voltage distribution networks,my research team started research where used TT system in rural areas of Fujian and urban areas to adopt TN-C-S system area.It is found that the user side equipment protection wiring is not standardized,and the user equipment of one station area may not be connected with the protection line,ground protection,zero connection protection.The risks of equipment grounding and zero protection mixed in the TT system and TN-C-S system are analyzed in the case of single-phase ground fault,phase line touches the outer shell and“Neutral line Broken”.It has practical guiding significance for Standarding equipment protection wiring.