The small current grounding line selection device simply selects the line with grounding fault and gives the indication signal.

In power system, the system with neutral point ungrounded or grounded by arc suppression coil and resistance is called small current grounding system. The most common fault in small current grounding system is single-phase grounding. When single grounding fault occurs in small current grounding system, all lines with capacitance to ground will have zero sequence current passing through. However, due to small zero sequence current and large dispersion, it is difficult to select grounding line; if there is arc suppression coil in the system, the difficulty will become greater.

When single-phase grounding, the grounding current is small. According to the provisions of safety operation regulations of power system, the system can continue to operate for 1 to 2 hours after the occurrence of single-phase ground fault. However, the non fault phase to ground voltage of the system will increase to line voltage. If it is not handled in time, it will easily develop into two-phase short circuit, which will expand the fault, and arc grounding will also cause over-voltage of the whole system. Through the small current grounding line selection device can accurately find the fault line, and through the alarm relay and communication mode to upload the information to the background, so that the staff can eliminate the ground fault within 2 hours, and ensure the reliability of power supply, it is a kind of protection equipment used in the power industry.

The above is the specific role of small current grounding line selection device. I hope it can help you. If you want to know more about electrical automation equipment and relay protection, please continue to pay attention to SMER website: http://www.smrdq.com