China’s domestic medium-voltage distribution network is widely used in the neutral point ungrounded operation mode. As economic and technological development progresses, and with the ongoing expansion of the power grid’s size and capacity, the application of cable lines is increasing accordingly. At present, in order to limit the capacitive current to the ground, an arc suppression coil is added at the neutral point. In the practical operation of the arc suppression coil grounding system, there are still fatal flaws in wire selection. Through reasonable circuit logic relationship and Ge 2 Sb 2 Te 5 current limiting device, this paper solves the problem that it is difficult to identify the fault line selection device, and there is a contradiction between the system arc extinguishing and the fault line selection in terms of technology, and solves the problem that the fault line selection of the distribution network grounded by the neutral point through the arc suppression coil is not accurate. In engineering use, it is more popularized to make better use of the existing arc suppression system and line selection device of users to reduce investment.