Abstract: Aiming at the problems of open circuit of phase current or neutral line current in secondary circuit of current transformer and two-point grounding of circuit under different working conditions, the method are put forward that under abnormal operating conditions such as inrush current and out-of-area fault, the amplitude and phase of the secondary current of different windings, the self-produced zero-sequence current and the external zero-sequence current are compared and analyzed, and the secondary current is correctly connected to the fault recorder, and consummates the inspection work measure ticket and so on. At the same time, the magnetic circuit characteristic of multi-tap transformer is analyzed, and the conclusion that secondary tap does not need short connection is obtained. The integrality of the secondary circuit of the transformer is ensured by the above methods, and the operation reliability of the secondary circuit is improved effectively.

Key words: current transformer, secondary circuit, open circuit, two point grounding, spare tap