What issues should be considered when topping up oil during transformer operation?

The oil replenishment work for a transformer that is short of oil can be carried out without powering off the transformer. When replenishing oil, the following items should be noted:

(1) Be careful to prevent oil mixing, and the newly replenished oil should pass the test

(2) Before refilling oil, the heavy gas protection should be switched to the signal position to prevent false activation of the gas protection, which could cause the transformer to trip

(3) After refilling oil, attention should be paid to checking the gas relay and releasing gas in a timely manner. Only after the transformer is fully evacuated of air can the heavy gas protection be reset to the tripping position

(4) The amount of oil replenishment should be appropriate, and the oil level should be compatible with the current oil temperature of the transformer

(5) It is prohibited to refill oil through the lower valve of the transformer to prevent sediment at the bottom of the transformer from being washed up into the coil, which could affect the insulation and heat dissipation of the transformer