原理：零序电流保护的基本原理是基于基尔霍夫电流定律：流入电路中任一节点的复电流的代数和等于零。在线路与电气设备正常的情况下，各相电流的矢量和等于零，因此，零序电流互感器的二次侧绕组无信号输出，执行元件不动作。当发生接地故障时的各相电流的矢量和不为零，故障电流使零序电流互感器的环形铁芯中产生磁通，零序电流互感器的二次侧感应电压使执行元件动作，带动脱扣装置，切换供电网络，达到接地故障保护的目的。
Principle: the basic principle of zero sequence current protection is based on Kirchhoff current law: the algebraic sum of complex current flowing into any node in the circuit is equal to zero. Under the normal condition of line and electrical equipment, the vector sum of each phase current is equal to zero. Therefore, the secondary winding of zero sequence current transformer has no signal output and the actuator does not act. In case of ground fault, the vector sum of each phase current is not zero. The fault current causes magnetic flux in the ring core of the zero sequence current transformer. The secondary side induced voltage of the zero sequence current transformer makes the actuator act, drives the tripping device, switches the power supply network, and achieves the purpose of ground fault protection.
作用：当电路中发生触电或漏电故障时，保护动作，切断电源。
Function: in case of electric shock or leakage fault in the circuit, the protection acts to cut off the power supply