可在三相线路上各装一个电流互感器，或让三相导线一起穿过一零序电流互感器，也可在中性线N上安装一个零序电流互感器，利用其来检测三相的电流矢量和。 On the three phase line each holds a current transformer, or let three-phase wires through the zero sequence current transformer, also can be installed on the neutral line N a zero sequence current transformer, current vector, and using it to detect three-phase. 在三相四线电路中，三相电流的相量和等于零，即Ia+Ib+IC=0 In a three-phase four-wire circuit, the amount of the three-phase current is zero, which is Ia + Ib + IC = 0 如果在三相四线中接入一个电流互感器，这时感应电流为零。当电路中发生触电或漏电故障时，回路中有漏电电流流过，这时穿过互感器的三相电流相量和不等零，其相量和为：Ia+Ib+Ic=I(漏电电流） If a current transformer is plugged into a three-phase four line, the induction current is zero. When electric shock or leakage faults in the circuit, leakage current through the loop, then through the transformer of three phase current phasor and range from zero, its phasor and as: Ia + Ib + Ic = I (leakage current) 这样互感器二次线圈中就有一个感应电压，此电压加于检测部分的电子放大电路，与保护区装置预定动作电流值相比较，如大于动作电流，即使灵敏继电器动作，作用于执行元件掉闸。这里所接的互感器称为零序电流互感器，三相电流的相量和不等于零，所产生的电流即为零序电流。 This transformer has a induced voltage in the secondary coil, the voltage on the detection part electronic amplifier circuit, compared with scheduled reserve device current value, such as greater than the current action, even sensitive relay action, acting on the components of tripping. The current transformer is called the zero sequence current transformer, the phase current of the three-phase current is not zero, and the resulting current is a zero sequence current.