Transformers and reactors of 220kV and above must be vacuum-filled with oil. Vacuum oil injection is recommended for 110kV models. The specific method is to evacuate the vacuum at a uniform speed until the specified vacuum degree is reached and maintained for 2 hours, then start to inject oil into the transformer oil tank. Throughout the oil injection process, the vacuum should be maintained, and the temperature of the injected oil should be slightly higher than that of the transformer body. When the oil is injected into the transformer at a speed of 3 to 5t/h and the distance from the top of the box is about 200mm, stop and continue to evacuate the air. The holding time should be no less than 2 hours for 110kV. 220kV shall not be less than 4 hours.
When the transformer is evacuated, the elastic deformation of the oil tank must be closely monitored, and its maximum value should not exceed twice the wall thickness. The allowable limit of vacuum pumping for transformers is: for 35kV transformers with a capacity of 4000 to 31500kVA, it should not exceed 0.051Mpa. For 110kV transformers with a capacity of 16,000 kVA or less, the pressure shall not exceed 0.051Mpa; for 110kV transformers with a capacity of 20,000 KVA or more, the pressure shall not exceed 0.051Mpa. Transformers of 220kV to 330kV shall not exceed 0.101Mpa.
Vacuum oil injection work should not be carried out on rainy or foggy days. When vacuuming the transformer, since the mechanical strength of the oil storage cabinet and the installed safety passage cannot meet the vacuuming requirements, if they are not removed, the glass film of the safety passage will be damaged, causing the glass to fall onto the transformer body, and the oil storage cabinet will also be damaged. Therefore, during vacuum oil injection, the oil storage cabinet and the safety passage should be removed and temporarily sealed with a cover plate.
Connect the cooling water source for the vacuum pump. Sufficient lighting and fire-fighting equipment are provided on site. After adjusting the oil level of the transformer oil pillow to the appropriate position through the oil drain valve at the bottom of the transformer, screw on the top vent hole of the oil pillow. Pay attention to checking the sealing of the vent hole. Tighten the screws on the casing lifting seat slightly (if there is oil leakage, tighten them further appropriately).
Remove the temporary oil gauge and other oil accessories of concern. Let the transformer stand still for at least 24 hours. During this period, carefully inspect all parts of the transformer (such as oil level, sealing performance, deformation, etc.), and at the same time, release the gas from the gas relay for an appropriate number of times. Take oil samples from the transformer for chemical and electrical tests.
It is widely applicable to power plants, power stations, power companies, power transformation industries, railways, petrochemicals, metallurgy and other fields. It is a dedicated equipment for power departments and industrial and mining enterprises to handle substandard transformer oil, instrument transformer oil, switch oil and other types of insulating oil. It is also the preferred choice for vacuum oil injection into power equipment and drying moisture in power equipment.
Confirm the matters related to the cooperation with the personnel of the transformer manufacturing plant and clarify the specific construction date. Implement the relevant process measures, organizational measures and measures as required.
Prepare sufficient qualified new oil, take oil samples for chemical and electrical tests, and analyze and conduct tests on the test data. Prepare vacuum oil purifiers, oil purifiers, vacuum pumps and other equipment, as well as oil drums, oil pipes, pipe joints, valves, vacuum gauges, seals, plug plates, oil filter paper, oil gauge tubes and other accessories, and ensure they are clean and free of impurities.