Shaanxi Hanzhong Transformer Co., ltd

Preventing transformers from getting damp is an essential part of on-site installation. The process of transformer oil treatment is closely related to preventing dampness. Nowadays, the capacity and voltage level of installed transformers are larger and higher respectively. In order to ensure the quality of transformer installation and avoid dampness, our company has established this enterprise standard.


Oil filtration preparation

  • Contact the transformer manufacturer through Party A to determine the transportation method of the transformer, the total weight of the oil required for installation, and the brand of transformer oil. Determine whether the transformer oil is transported in barrels or tanks. If transported in tanks, determine whether the oil tanks can be used on site during transformer installation.

  • According to the transformer manufacturer's information, plan the construction site, equip with high-vacuum oil filtration machine, flat plate oil filtration machine, filter paper, vacuum pump, vacuum pump oil, mercury vacuum gauge, pointer vacuum gauge, pointer pressure gauge, oil tester, oil pipe, valve, and oil storage tank. The oil pipe and vacuum pumping pipe of the transformer can be reinforced with PVC plastic hose. To improve the quality of oil filtration, the oil storage tank should be equipped with a moisture absorber.

  • Set up temporary power supply box, water source and fire extinguishing equipment on site.

  • The oil filtration machine, vacuum pump, oil storage tank, oil pipe, transformer, and temporary power supply box must be reliably grounded.

  • If the brand of remaining oil in the oil filtration machine and the oil storage tank is different from the new oil’s brand, the remaining oil in the oil filtration machine and the oil storage tank should be moved out and stored separately. Clean the inside of the oil storage tank and keep it sealed and clean. Check whether the color of the desiccant inside the moisture absorber is normal and whether the oil seal oil level is normal.

  • Acceptance of transformer oil:

    For each batch of new oil that arrives on site, if a full analysis has been carried out at the equipment manufacturer and accompanied by test records, a simplified analysis should be carried out. If the oil comes directly from the refinery or is purchased from the market, or if there is doubt about the oil supplied by the manufacturer, a full analysis must be carried out.

    Sampling quantity: For large tanks of oil, samples should be taken for each tank, and for small tanks of oil, take samples according to the table below:


The sampling test shall be carried out in accordance with the current national standard "Sampling of Power-Use Oils (Transformer Oil and Steam Turbine Oil)". The test standard shall comply with the current national standard "Test Standard for Electrical Equipment Handover Test for Electrical Installation Projects".

Different brands of transformer oil should be stored separately and marked clearly.

When draining the oil, visually inspect if there is anything abnormal on the upper and lower parts of the transformer oil transported by the tanker; for the transformer oil transported in small barrels, visually check each barrel, identify the smell, and ensure that the brand labels of all the barrels are consistent.

Method and steps of oil filtration

  • When draining the oil from the oil tank, connect the oil pipeline, and the high-vacuum oil filtration machine will self-circulate and raise the oil temperature, and the oil filtration machine will clean itself. Use the oil filtration machine to clean the hot oil and flush oil pipeline. The inside of the oil storage tank can be cleaned without flushing with transformer oil. The flushing oil should be stored separately and marked properly.

  • When draining oil from barrels, use a flat plate oil filtration machine. Before using the flat plate oil filtration machine, the inside should be cleaned. A galvanized pipe should be used to extend into the oil barrel, and the front end of the pipe opening should be processed at a 45° angle. Both ends of the pipe opening should be polished smoothly, and the inside and outside of the galvanized pipe must be scrubbed clean before use. When extracting the oil from the bottom of the barrel, check the quality of the oil at the bottom of the barrel. If there are many impurities, the oil at the bottom can be omitted.

  • After the arriving transformer oil is introduced into the oil storage tank through the oil filtration machine, filter the transformer oil with the high-vacuum oil filtration machine. To improve the oil filtration effect, the oil filtration of the oil storage tank should adopt the method of pouring oil from one oil storage tank to another, i.e., filter all the oil in one oil storage tank through the high-vacuum oil filtration machine into another oil storage tank, and then filter it back to the original oil storage tank. If there are few oil storage tanks on site, a self-circulating oil storage tank should be used, and the oil storage tank should be sealed properly. The outlet temperature of the oil filtration machine should not be lower than 50℃. After filtering the transformer oil, take an oil sample for testing to determine whether the transformer oil purification process meets the standard. The oil sample can be taken from the oil sampling valve of the oil filtration machine.

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