Why vacuum pump should be adopted for oil-filling in transformer ?
Becuase vacuum condition can avoid oil being oxidized that would decrease the insulation degree of tranfromer.
Transformer above 220kV must adopt vacuum oil-filling. It is suggested to be used for 110kV tranformer.
Oil filling working process:
1) Preparation, to connect all necessary device into transformer, such as vacuum pump, oil filter press, oil tank, etc.
2) Start the vacuum pump. The vacuum degree should be enhanced in constant speed, meet 1.3Kpa within 1 hour,and be kept for 30 minutes
3) Check and inspect the components of transformer, if no abnormalty, keep on evacuating. When vacuum degree meet or is less than 50Pa, maintain it for 6 hours.
4) Observation & records
5) Keep on evacuating and fill oil.Stop filling when oil level is 100-150mm away from top.
6) Keep evacuating and remain the vacuum degree for 8 hours, till now the vacuum degree should not be over 50Pa.
EVP roots-rotary vane pump unit is the ideal option for vacuum oil-filling. it’s ultimate pressure is around 5Pa.This unit equipped with automatic control unit for easy operation. The backing pump equipped with inlet liquid filter and gas ballast valve has more stable performance for moisture suction.