In the small current grounding system, single grounding is a common temporary fault, which often occurs in wet and rainy weather. When single-phase grounding occurs, the fault phase to ground voltage decreases and the non fault two-phase phase voltage increases, but the line voltage is still symmetrical, which does not affect the continuous power supply to users. The system can run for 1 ~ 2 hours, which is also the advantage of small current grounding system.

When single-phase grounding fault occurs, it can automatically extinguish arc and recover insulation in most cases. However, in case of permanent grounding fault, in order to prevent the expansion of fault caused by the rise of non fault phase voltage, the fault line must be determined and removed as soon as possible, which puts forward the problem of single-phase grounding fault line selection. The smr-zn09 series small current grounding line selection device developed by our company can be accurate Find the fault line and upload the information to the background through alarm relay and communication.

In the operation of small current grounding power grid, when single-phase grounding fault occurs, the operator on duty should handle it calmly. According to the signal, voltmeter indication, weather condition and operation mode, the virtual and real grounding signals are distinguished. And timely report to the superior dispatching and leaders, and make records of relevant phenomena. In judging and processing, the nature and phase of the fault should be identified according to the characteristics of the ground fault. Secondly, it is necessary to consider the power balance and relay protection coordination among different parts during the operation.