The commonly used detection methods for transformer faults consider the complexity of transformer structures and the diverse forms of faults. It is difficult for pilot holding to obtain the nature and faults of transformer faults. In general, there are several fault detection methods that can be used. Transformer insulation resistance test In the insulation resistance test, by conducting some inspections, a clearer understanding of the overall moisture content of the transformer insulation, the surface moisture content of the components, dirt, and the concentrated defects of the penetration can be obtained. Transformer leakage current test In the leakage current test, due to its high sensitivity, it can timely determine the sealing condition of the transformer bushing and the crack situation of the high-voltage bushing. The pilot test controlled and discovered defects that were difficult to detect during the test. Transformer AC withstand voltage test can detect local defects in the main insulation of the transformer, such as moisture, cracking or looseness of the winding main insulation, as well as dirt attached to the winding insulation