How Zero Sequence Current Transformer Neutralizes

The zero-sequence current is caused by the unbalance of three phases A, B, and C on the power grid. There will be zero-sequence current on the N line. A Zero Sequence Current Transformer is installed here to reduce the zero-sequence current and collect it. , to achieve zero-sequence current compensation.

The transformer is to measure the current of a single energized wire, and the Zero Sequence Current Transformer can also measure the current on the neutral loop alone, and can also measure the live wire and the neutral wire together.

Principle: The basic principle of the Zero Sequence Current Transformer is based on Kirchhoff's current law: the algebraic sum of the complex currents flowing into any node in the circuit is equal to zero. When the line and electrical equipment are normal, the vector sum of the currents of each phase is equal to zero. Therefore, the secondary winding of the Zero Sequence Current Transformer has no signal output, and the actuator does not act. When the ground fault occurs, the vector sum of the currents of each phase is not zero, the fault current generates magnetic flux in the annular iron core of the Zero Sequence Current Transformer, and the induced voltage on the secondary side of the Zero Sequence Current Transformer causes the actuator to act and drive the tripping. device, switch the power supply network, and achieve the purpose of ground fault protection.

Function: When an electric shock or leakage fault occurs in the circuit, the protection action will cut off the power supply.

Use: Install a current transformer on each of the three-phase lines, or let the three-phase wires pass through a Zero Sequence Current Transformer together, or install a Zero Sequence Current Transformer on the neutral line N, and use it to detect the three-phase The current vector sum.