The high-voltage incoming line is a three-phase three-wire system. Usually, the current of the three-phase electric current is balanced. The zero-sequence transformer uses the principle of electromagnetic induction to measure the three-phase unbalanced current. If there is a one-way ground fault, the zero-sequence transformer measures the current reflected. Relay protection, thus alarming or tripping.
Principle: The basic principle of zero-sequence current protection 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. In the case of normal line and electrical equipment, the vector sum of the currents of the phases is equal to zero. Therefore, the secondary winding of the zero-sequence current transformer has no signal output, and the actuator does not operate. When the ground fault occurs, the vector sum of each phase current is not zero, the fault current causes magnetic flux to be generated in the toroidal core of the zero-sequence current transformer, and the secondary side induced voltage of the zero-sequence current transformer causes the actuator to act, driving The tripping device switches the power supply network to achieve the purpose of ground fault protection.
Shenzhen Kangpusen Technology Co., Ltd.;