Transformer is an extremely important electrical equipment in the power transmission and distribution system, but due to various reasons, it sometimes fails during operation. According to the nature of the maintenance work, transformer maintenance is divided into overhaul and minor repair. It is customary that oil-immersed transformers that require oil-releasing hanging cores (or hanging bell covers) for maintenance are called overhauls; if they do not need oil-releasing, they do not hang the cores (hanging bell covers) and only perform external maintenance or refueling Performing oil treatment is called minor repair. First, the conventional transformer maintenance process 1. Clean the bushing and check the porcelain sleeve for signs of discharge and damage; 2. Check whether the fastening bolts on the top of the bushing are loose. Whether it is overheating; 3. Clean the transformer oil tank and the oil storage tank, safety air channels and pressure regulating devices and other accessories; 4. Check the dust and other debris deposited in the valve cover of the pressure relief valve; 5. Check whether the oil level of the oil storage tank is normal. Whether the oil level gauge is intact and clean, and drain the oil in the sewage collection tank; 6. Check the respirator and replace the desiccant that has failed to change color; 7.