保定零序电流互感器电气厂

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 phase amount of the three-phase current is equal to zero, that 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 connected in a three phase four line, the induction current is zero. When there is an electric shock or a leakage fault in the circuit, there is a leakage current flowing through the loop. At this time, the three phase current phasors and equal zeros passing through the transformer are phased and the phase is 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。

In this way, there is an induced voltage in the two coil of the transformer. The voltage is added to the electronic amplifying circuit of the detection part, which is compared with the predetermined action current value of the protective device, such as greater than the action current, even if the sensitive relay acts, it acts on the execution element to turn off. The mutual inductor attached here is called zero sequence current transformer. The phase amount of the three-phase current is not equal to zero, and the current produced is zero sequence current.

产生零序电流的两个条件:

Two conditions for generating zero sequence current:

1、无论是纵向故障、还是横向故障、还是正常时和异常时的不对称，只要有零序电压的产生；

1, whether it is a longitudinal fault, or a transverse fault, or a normal and abnormal asymmetry, as long as the zero sequence voltage is produced;

2、零序电流有通路。

2. The zero sequence current has a path.