ZCT Zero sequence leakage protection CT

What is the Zero sequence current transformer?
Zero sequence current transformer is a single turn through center type current transformer. It is generally used for power protection equipment, such as small current grounding line selection device and microcomputer harmonic elimination device.

When the zero-sequence grounding current is generated in the power system, the zero-sequence current transformer is used in conjunction with the relay protection device or signal to make the device components move 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, making the equipment on the secondary line to act as a protection (cut off the power supply, alarm, etc.).

Zero sequence current protection on the specific application in the three phase line and a current transformer (CT), or let three-phase wires through the zero sequence CT, can also be installed on the neutral line N a zero sequence CT, use the C.T to detect three-phase current vector, and the zero sequence current Io, IA + IB + IC = Io, when answered the three-phase load balancing in full on links (no grounding fault, and no account of leakage current circuit, electrical equipment), Io = 0;When the three-phase load connected on the line is unbalanced, Io=IN, then the zero sequence current is unbalanced current IN;When a ground fault occurs IN a certain phase, a single-phase ground fault current Id must be generated. At this time, the detected zero-sequence current IO=IN+Id, which is the vector sum of the three-phase unbalanced current and single-phase ground current.