How to use zero sequence residual current transformer

- Sep 30, 2020-

A current transformer can be installed on each of the three-phase lines, or the three-phase wires can pass through a zero-sequence current transformer together, or a zero-sequence current transformer can be installed on the neutral line N to detect the three-phase The vector sum of currents. In a three-phase four-wire circuit, the phasor sum of the three-phase current is equal to zero, that is, Ia+Ib+IC=0. If a current transformer is connected to the three-phase four-wire circuit, the induced current is zero at this time. When an electric shock or leakage fault occurs in the circuit, a leakage current flows in the circuit. At this time, the phasor sum of the three-phase current passing through the transformer is not equal to zero, and the phasor sum is: Ia+Ib+Ic=I (leakage Current) In this way, there is an induced voltage in the secondary coil of the transformer. This voltage is applied to the electronic amplifier circuit of the detection part and compared with the predetermined operating current value of the protection area device. If it is greater than the operating current, even if the sensitive relay operates, it will act on The component is off. The transformer connected here is called a zero-sequence current transformer. The phasor sum of the three-phase current is not equal to zero, and the generated current is the zero-sequence current.https://www.ctsensorducer.com/