The role and principle of zero sequence current transformer

- Apr 10, 2019-

Zero sequence current transformer are typically used in conjunction with relay protection devices or signals when the power system produces zero-sequence ground currents to cause device components to operate for protection or monitoring. The zero sequence current transformer is a single-turn through-core current transformer, which is generally used for power protection equipment, such as a small current grounding line selection device and a microcomputer harmonic elimination device. When an electric shock or leakage fault occurs in the circuit, the secondary side of the transformer outputs a zero-sequence current, so that the equipment on the connected secondary line is protected.

The zero-sequence current protection of the zero sequence current transformer is generally suitable for use in the TN grounding system. As long as the setting is appropriate, the zero-sequence current in the event of a ground fault can be detected to cut off the faulty loop. For IT systems, it is generally used in industrial and mining enterprises that require high reliability of power supply, do not need to immediately cut off the power supply circuit for single-phase grounding, but need to issue insulation damage monitoring signals to maintain power supply for a period of time. Three-phase three-wire distribution line of the sex line.

When the single-phase is grounded, the zero-sequence current flowing through the faulty line is the sum of the capacitance of the whole system non-faulty system, so it is easy to detect the ground fault current, so the zero-sequence current protection device can be used to monitor the first ground fault.