In recent years, with the implementation of the power grid transformation project, 10kV distribution lines have been transformed from the original "two lines and one ground" power supply mode to the "three-phase three lines" power supply mode with ungrounded neutral point. The change of power supply mode of 10kV distribution lines has enhanced the insulation level of distribution lines, reduced the tripping rate of distribution lines, improved power supply reliability and reduced line losses. However, in the actual operation of the new power supply mode, single-phase grounding faults often occur, especially in the severe weather conditions such as strong wind, rainstorm, hail, snow, etc., which seriously affect the safe and economic operation of the substation equipment and distribution network. After the fault occurred, due to the wide range of line length, it is difficult to find the fault point quickly and accurately by using traditional methods such as pushing and pulling by sections and checking the tower step by step based on previous experience, which is time-consuming and laborious, with large power outage range and long time. Kdjk-20a overhead line grounding fault finder is used to quickly and accurately locate the grounding point after the power failure of 10kV fault line, and can realize the rapid search of distribution network equipment in case of fault. Reduce the labor intensity of line maintenance personnel, save time and effort, and improve work efficiency, power supply reliability and economic benefits of power enterprises. The company has used the domestic DC grounding fault location technology, small current grounding fault location and other principles developed by the company, invented the "s injection method" principle, and successfully developed the "high voltage constant current open circuit, AC signal automatic tracking and location" technology. Based on the Fourier algorithm, the company has developed the "distribution network single phase grounding fault locator", which has made a major breakthrough in the operation method of 10kV (35kV) distribution network single-phase grounding fault location. It solves the problems of customer complaints caused by the failure to find the grounding fault point for a long time and the economic benefits caused by the reduction of electricity sales; It also solves the problem that a lot of manpower and material resources are consumed due to the human sea tactics, that is, manually climbing the pole step by step to find the grounding fault. Kdjk-20a overhead line ground fault finder can find the ground fault point in a very short time. The instrument is powered by a built-in battery. It can work for more than 5 hours at a time and weighs less than 8kg. It is practical and convenient, which solves the above problems well, and makes the power failure line inspection more accurate, fast, convenient and easy. It has the advantages that traditional methods can not compare.