The cooling system of main transformer is OWDF forced oil circulating mmiri cooling system, which is used to cool the insulating oil of transformer. It mainly includes: submersible oil pump, cooler, flowmeter, leak detector, inlet and outlet hydraulic valve, inlet and outlet mmiri pressure gauge, total inlet water flow meter, outlet water flow meter, outlet water temperature meter, etc. The cooler oil pipe is installed at the upper and lower parts of the transformer body. During normal operation, the submersible oil pump sends the insulating oil of the main transformer to the cooler from the top of the transformer, and then flows to the lower part of the transformer from the oil drain pipe of the transformer. In the cooler, the cooling water flows through the water pipe of the cooler, and the oil and water conduct heat exchange to reduce the oil temperature of the main transformer. A flow of oil is formed in the transformer from bottom to top. When the oil flows through each element, the insulating oil of the main transformer exchanges heat with the heating element to cool the transformer.

The cooler is composed of cooling oil chamber, cooling water pipe, upper and lower water chambers and water leakage detector. The cooling water pipe is composed of 36 double-layer copper pipes. The outer tube is a spiral pneumatic tube with high thermal conductivity, good compression resistance and impact resistance; The inner pipe is a kind of corrosion resistant bare pipe with strong corrosion resistance. The double-layer copper pipe is fixed on the upper and lower flanges after being “expanded” to connect the space between the double-layer copper pipe and the fixed flange cavity. It is fixed at the upper and lower ends of the oil chamber of the cooler. The water chambers at the lower end of the cooler are separated from each other, and are respectively water inlet and outlet chambers.

The cooling water flow in the cooler can be adjusted by adjusting the inlet and outlet valves of the cooler. When the wall of double layer cooling water pipe breaks, water or oil will flow from the damaged part to the double layer water pipe, and flow to the water leakage detector through space at the lowest point, The electric contact is connected and sends a water leakage signal from the cooler.