Zero sequence current transformer is also called residual current transformer, grounding current transformer or leakage current transformer, which is used to detect neutral unbalanced current, generally used in conjunction with relay protection device. Electrical compliance has the same meaning as common current transformers.
Zero sequence current transformer is one of the current transformers. In gb20840, the definition of protection current transformer is: current transformer transmitting information signal for protection and control device. Therefore, it is a special protection current transformer. The national standard applicable to current transformer is GB1208-2006, The article about the zero sequence current transformer is the protection current transformer. All the articles about the protection current transformer refer to the zero sequence current transformer.
Zero sequence current transformer is used together with relay protection device or signal when zero sequence grounding current is generated in power system to make device elements act and realize protection or monitoring. In case of electric shock or leakage fault in the circuit, the secondary side of the transformer outputs zero sequence current to make the equipment protection action (cut off the power supply, alarm, etc.) on the connected secondary line.https://www.ctsensorducer.com/