In the small current grounding system, some faults will occasionally occur, but because the fault characteristics are not obvious, it is difficult to find them in time. However, if the grounding arc exists for a long time, it may burn out the insulation of the grounding point, resulting in phase to phase short circuit fault. In general, the common fault causes in small current grounding system are: single phase insulation breakdown of motor winding, discharge to ground, theft and stripping of power cable, causing single-phase cable core leakage discharge, overhead line broken by branches or hanging by crane.

        In the process of small current grounding system failure, small current grounding line selection device can be used. This kind of small current grounding line selection device can measure the distribution line grounding before the distribution line grounding, More attention should be paid to the installation of small current grounding line selection device and zero sequence current transformer with interval in each distribution line.

        But the installation of small current grounding line selection is to prevent accidents and solve problems in case of faults. We still need to solve the problem from the root and take preventive measures.

        First of all, the distribution line should be inspected regularly, mainly to check the distance between the wire and trees and buildings, whether there is a bird's nest at the top of the pole, whether the wire is bound or fixed firmly in the insulator, whether the insulator fixing bolt is loose, whether the stay wire bolt is loose, whether the stay wire is broken, whether the sag is too large or too small, etc.