We have no way to avoid the single-phase grounding fault in the small current grounding system, especially in the rainy season, wind and snow and other adverse conditions, the single-phase grounding fault occurs more frequently. What we can avoid is the damage and accident when single-phase ground fault occurs.

Small current grounding system has an obvious advantage, that is, after the occurrence of single-phase ground fault, the system can still supply power normally. But it only lasts about two hours. So we have to make use of this precious time, we must find out the fault point as soon as possible and eliminate it, so as to ensure the normal operation of the line.

In the absence of small current grounding line selection device, often rely on manual one by one line to find the fault point. This kind of search method must stop the power supply to all lines, resulting in the blackout of some lines that can supply power normally, resulting in some unnecessary blackouts, which is obviously not a long-term solution.

It is in this environment that people create and study the "small current grounding line selection device". After different technologies and different requirements, they transform and upgrade the small current grounding line selection device. At present, the small current grounding line selection device on the market has the advantages of fast operation speed, strong anti-interference ability, low power consumption and high line selection accuracy. After making accurate judgment, they directly cut off the grounding fault Block the line. The manual maintenance workload and cost are reduced.

It is difficult to estimate the loss of the whole national economy and people's life quality caused by single-phase grounding fault power failure in small current grounding system. Therefore, reliable power supply is the social responsibility of power supply enterprises, and power failure will greatly reduce people's quality of life.