For production enterprises, the continuity, reliability and safety of power supply are very important. In case of power failure, it will cause incalculable losses to the normal production of enterprises.

        During the normal operation of the substation, single-phase grounding fault occurs frequently. According to the power regulations, single-phase grounding fault can operate with fault for 1-2 hours, but single-phase grounding fault will cause the rise of normal phase voltage, which may lead to insulation breakdown, expand the fault, and even develop into phase to phase short circuit, which will cause greater harm to the safety of system operation, Therefore, it is necessary to quickly find out the fault line and eliminate it.

        When a fault occurs, the operation and maintenance personnel cannot find out which circuit has a single-phase grounding fault in time, let alone further remove the fault, which brings certain blindness to the operators. Therefore, it is very necessary to install a small current grounding line selection device.