When single-phase grounding fault occurs in small current system, in order to prevent the fault from expanding due to the rise of non fault phase voltage, the fault line must be determined and removed as soon as possible. The function of small current grounding line selection device is to find the fault line accurately, and upload the information to the background through alarm relay and communication.

Now for the new substation, the configuration of zero sequence current transformer still meets the requirements, because when purchasing the small current grounding line selection device, we will explain to customers that the small current grounding line selection device produced by the same manufacturer is used together with the zero sequence current transformer, because the two different devices of the same manufacturer are relatively more stable and compatible than the two devices of different manufacturers Good.

However, the line of equipment transformation or new operation is not so standardized. It is often found that the newly installed zero sequence current transformer is not the same as the previous model or even the transformer ratio. The installation drawing of the zero sequence current transformer in the newly put into operation line is convenient. It is removed before the cable is put through, but it is forgotten to connect it when the cable is put through. Cable workers do not know much about the selection of small current grounding lines, and it is still common for zero sequence current transformers to forget to connect, which involves the coordination of various professional departments.

The solution to this problem is to pay attention to the acceptance, improve and strictly follow the acceptance standard, emphasize the importance of zero sequence current transformer wiring, and introduce this requirement in the relevant professional specifications, especially for a equipment transformation or new lines put into operation, so that the professional staff have a clear idea To strengthen the coordination and cooperation of professional departments to ensure the continuity of maintenance.