零序电流保护具体应用可在三相线路上各装一个电流互感器(CT)，或让三相导线一起穿过一零序CT，也可在中性线N上安装一个零序CT，利用这些C.T来检测三相的电流矢量和，即零序电流Io，IA+IB+IC=Io，当线路上所接的三相负荷完全平衡时(无接地故障，且不考虑线路、电器设备的泄漏电流)，Io=0;当线路上所接的三相负荷不平衡，则Io=IN，此时的零序电流为不平衡电流IN;当某一相发生接地故障时，必然产生一个单相接地故障电流Id，此时检测到的零序电流IO=IN+Id，是三相不平衡电流与单相接地电流的矢量和。
The specific application of zero sequence current protection can install a current transformer (CT) on three-phase lines, or let three-phase conductors pass through one zero sequence CT together, or install a zero sequence CT on neutral line N. These C.T can be used to detect the sum of three-phase dianbiao.37ix.com.cnjingdianji.37ix.com.cnshusongdaib.07858.net shusongdain.07858.net zhushiguan.07858.netfangdaomenb.89ix.comcurrent vectors, i.e. zero sequence current Io, IA+IB+IC=Io. When the three-phase loads connected on the lines are completely balanced (without grounding fault, and without considering lines, lines and IC=Io). Leakage current of electrical equipment, Io = 0; When the three-phase load connected on the line is unbalanced, then Io = IN, the zero-sequence current is unbalanced current IN; When a phase grounding fault occurs, a single-phase grounding fault current Id will inevitably occur, and the zero-sequence current IO = IN + Id detected at this time is the vector sum of three-phase unbalanced current and single-phase grounding current.