Transformer vacuum oil filling and oil filtering operation
(1) The purpose of vacuum oil injection
Vacuum oil injection can greatly reduce the content of transformer oil and water, thus greatly enhancing the breakdown strength of transformer oil, that is, reducing the oil gap distance of the body insulation, resulting in greatly reduced transformer design costs.
Attention:
Transformer oil filtration and oil injection should be carried out in fine weather. Transformer drain valve port should be matched with the oil filter inlet pipe port.
Oil filter should be filled with vacuum tank oil standard tube 1/2 qualified oil.
(2) Transformer Oil Filter in operation
Open the oil pillow cover of the transformer, insert the oil filter outlet pipe under the oil level on the oil pillow, and then seal the oil pillow cover with clean filter paper or film.
Insert the inlet line of the oil filter into the oil drum prepared with qualified oil.
Open the oil drain valve at the bottom of the transformer and drain 3-5% of the oil of the transformer (3-5% of the oil is mainly impurities and water, and should be stored separately.
After the oil drain valve at the bottom of the transformer is discharged by 3-5%, the oil filter is pumped into a high vacuum (not less than -0.09Mpa) and the oil level of the transformer oil pillow meets the requirements, the oil inlet pipe of the oil filter is connected to the oil drain valve. At this time, the oil filter can work normally.
After the hot oil circulation of the transformer is completed and the oil injection is completed, it should be left standing for a period of time before applying the voltage. 110KV needs to stand for 24h; 220KV needs to stand for 48h.
Note: After the transformer is resting, it should be vented several times from the transformer's bushing, elevating seat, cooling device, gas relay and pressure release device, and should start the submersible oil pump until the residual gas is exhausted.
(3) Oil injection of newly installed transformer
Oil filter and newly installed Transformer Vacuum
After all transformer accessories are installed. Open all valves of the connecting body of the accessories and components, and vacuum all accessories (including coolers and radiators) except the oil storage tank and gas relay. If the oil storage tank is designed in full vacuum, the oil storage tank and gas relay are also vacuumed.
When vacuuming, close the vacuum valve on the transformer body, check that the vacuum pipe system does not leak, and open the vacuum valve to vacuum the transformer. After the vacuum degree of the transformer reaches the specified value, the vacuum holding time can be filled with vacuum oil only after the specified time is reached (generally keeping the vacuum for 3 to 8 hours is conducive to moisture volatilization).
Vacuum oiling
The transformer oil must be injected into the transformer after the oil sample test is qualified according to the current national standard "Electrical Equipment installation Engineering Electrical equipment handover test Standard".
After checking that all parts are normal, open the oil inlet valve of the oil filter device and the oil outlet valve of the oil tank. After the insulating oil enters the oil tank of the oil filter device, turn on the heater.
After the liquid level in the oil tank reaches the observation window position, open the oil outlet valve and the oil filling valve of the transformer, and open the oil outlet pump to fill the transformer with oil (in order to ensure that the oil is clean and free of impurities, a small amount of oil can be discharged before filling the transformer to clean the tubing and connecting accessories).
The oil injection speed should not be greater than 1800L/h, and the transformer is vacuumed while the oil is injected.
Fill the oil to the specified oil level of the oil storage tank, and the corresponding temperature position should be slightly higher according to the temperature curve of the oil level.
The oil filling is finished, and the shutdown operation is the same as that of oil filtering.
After oil injection, it should continue to maintain direct air, holding time :110kV transformer shall not be less than 2h, 220KV transformer shall not be less than 4h.
Transformer hot oil cycle operation
Hot oil circulation must be carried out after vacuum oil injection for transformers with voltage grades of 220kV and above. Cycle time: 110kV transformer general hot oil cycle 24 hours, 220kV transformer should not be less than 48 hours.
Connect the oil filter to the transformer, connect the oil filter inlet pipe to the bottom valve of the transformer, the outlet pipe to the top valve of the transformer, and the hot oil is injected from the top of the transformer.
Start the oil filter vacuum pump, first open the oil filter side inlet valve and outlet valve, use the oil filter vacuum pump to evacuate the air in the oil pipe, and then open the valve at the bottom of the transformer for circulating transformer heating.
Hot oil circulation precautions:
Before hot oil circulation in full oil state, check that the moisture absorber is correctly installed and breathing is smooth.
When the hot oil is circulating, the outlet oil temperature of the oil filter should not be lower than 50 ° C, and the temperature in the tank should not be lower than 40 ° C.
After the oil sampling inspection of hot oil circulation, it should meet the provisions of the current national standard "Electrical equipment handover test Standard for Electrical equipment Engineering".
After the hot oil circulation of the transformer is completed and the oil injection is completed, it should be left standing for a period of time before applying the voltage. 110KV needs to stand for 24h; 220KV needs to stand for 48h.
After the transformer is static, it should be vented several times from the Transformer Bushing, elevating seat, cooling device, gas relay and pressure release device, and should start the submersible oil pump until the residual gas is exhausted.