1、Transformer pumping vacuum oil injection before the overall installation of the transformer should be completed.
2、Transformer with load regulator switch, the switch oil tank and transformer oil tank are connected in parallel with the evacuation pipe, so that the switch oil chamber and transformer oil tank are evacuated at the same time (the oil in the switch oil chamber should be released before evacuation). The oil filling pipeline of the switch oil chamber is also connected in parallel with the oil filling pipeline of the transformer tank, so that the switch oil chamber and the transformer tank are evacuated and filled with oil at the same time.
3、On the condition that the sealing performance of transformer and piping system is good, vacuuming can be carried out.
4、If the temperature of the body is lower than 20℃ before evacuation, the body should be heated to above 20℃. Heat it by hot oil circulation, and the oil temperature at the outlet of oil filter should be 50~70℃, and the oil quality standard should meet the requirement before oil injection.
5、Before evacuating, the transformer which is allowed to evacuate through the oil storage cabinet should connect the evacuation pipeline to the special oil replenishment valve on the oil storage cabinet; the transformer which is not allowed to evacuate through the oil storage cabinet should connect the evacuation pipeline to the valve on the end of the dominant gas linkage pipe of the transformer. In order to monitor the transformer oil level, the valve outlet at the end of the dominant gas linkage pipe and the bottom of the transformer oil injection valve outlet is equipped with an oil level pipe, which can use φ20 PVC plastic hose. A special connection should be made to connect with the transformer body vacuum valve and transformer oil injection valve. Connect vacuum pipe, oil level pipe and mercury vacuum gauge on the transformer body vacuum valve connector. Oil injection valve connection is connected with oil injection tube and oil level tube.
6、For the transformer which is allowed to draw vacuum through the oil storage cabinet, open the valves at both ends of the gas relay before drawing vacuum, open all the valves connected between the radiator and the transformer, and draw vacuum at the same time for the accessories which are allowed to draw the same vacuum. For the accessories which are not allowed to draw vacuum, such as safety air channel, the valve connected with oil tank should be closed.
7、For the transformer which is not allowed to draw vacuum in the oil storage cabinet, close the valves at both ends of the gas relay before drawing vacuum, and open all the valves connected with the oil tank for the accessories which are allowed to draw the same vacuum, such as radiator, etc., and draw vacuum at the same time. The accessories which are not allowed to draw vacuum (such as safety air channel, etc.) should be isolated from the oil tank.
8、Vacuum injection and oil replenishment should not be carried out in rainy or foggy days.
9、Vacuum oiling is suitable for 110kV transformer, vacuum oiling is necessary for transformers of 220kV and above voltage level. The allowable value of transformer vacuum should be as specified by transformer manufacturer, without manufacturer's specification, it should be in accordance with the provisions of Table 2.5.3. Vacuum holding time: 220~330kV transformer, not less than 8 hours; 500kV transformer, not less than 24 hours. When evacuating, the elastic deformation of oil tank should be monitored and recorded, and its maximum value should not exceed 2 times of the wall thickness.
The limit allowable value of transformer evacuation
|Voltage (kV)||Capacity (kVA)||Vacuum (MPa)|
|16000 and below||0.051|
|20000 and above||0.08|
|220 and 330||0.101|
10、When evacuating, first close the transformer body evacuation valve, check that there is no leakage in the evacuation pipeline system, then open the evacuation valve for transformer evacuation. Record the start time of evacuation, and then record the vacuum value every hour. After the transformer vacuum reaches the specified value and the vacuum holding time reaches the specified time, then the transformer can be filled with oil under vacuum.
11、Transformer oil injection under vacuum.
Transformer oil must be in accordance with the current national standard "electrical installation project electrical equipment handover test standards", take oil samples after passing the test, before injecting into the transformer. Different grades of insulating oil or the same grade of new oil and run through the oil mix before use, must do oil mixing test.
Transformer oil injection is appropriate from the lower oil valve injection. For the transformer oriented to strong oil circulation, oil injection should be carried out according to the manufacturer's regulations.
Check the equipment grounding point and oil pipeline before oil injection should be grounded reliably.
The whole process of oil injection should keep vacuum, and the temperature of injected oil should be higher than the temperature of the body.
The speed of oil injection should not be greater than 100L/min.
Observe the oil level tube, the gap between the oil surface and the top of the oil tank should not be less than 200mm or according to the manufacturer's regulations. After oil injection, the vacuum should be kept, and the keeping time: 110kV transformer should not be less than 2h; 220kV transformer should not be less than 4h; 500kV transformer may not keep the vacuum after full oil injection.
Allow the transformer of oil storage cabinet to draw vacuum, after keeping the oil filling vacuum to the specified time, inject oil directly from the bottom valve to the slightly higher oil level specified in the oil filling cabinet. Close the vacuum valve and vacuum pump, and use dry air to lift the vacuum of oil storage cabinet in oil replenishment valve.
For the transformer which does not allow the oil storage cabinet to draw vacuum, after keeping the oil filling vacuum to the specified time, close the vacuum drawing valve and vacuum pump. Open the valves at both ends of the gas relay, and at the same time, use dry air to lift the transformer vacuum in the oil reservoir filler valve. After relieving the vacuum, use the oil reservoir oil filling valve to fill the transformer with oil, and discharge the gas in the body and accessories when filling the oil. Oil injection to the oil reservoir specified oil level is slightly higher. Gas discharge in the oil conservator must be carried out according to the manufacturer's regulations.
For the transformer of corrugated oil storage cabinet, after oil injection vacuum is maintained to the specified time, close the evacuation valve and vacuum pump. Open the valves at both ends of the gas relay, and at the same time lift the transformer vacuum with dry air in the oil reservoir filler valve. After relieving the vacuum, continue to fill oil from the bottom, open the oil reservoir fill valve and let the gas escape from the fill valve. Discharge the gas in the body and accessories at the same time. When there is oil overflow from the oil filler valve, close the oil filler valve and continue to fill the oil tank to make it expand and fill it to the specified oil level slightly higher.