TRANSFORMER WITH ON-LOAD TAP CHANGER

PROBLEM TO BE SOLVED: To provide a gas-sealed oil-immersed transformer, which is provided with an on-load tap changer and can prevent violent explosion of the oil tank of the tap changer and the extreme drop in the surface level of insulating oil in the oil tank, by reforming the hermetically sealing structure of the tap changer. SOLUTION: This gas-sealed oil-immersed transformer is provided with the on-load tap changer, having a change-over switch 3 which is provided from the inside to the outside of the body tank 9 of the transformer and immersed in insulating oil 6 separated from the insulating oil 10 stored in the tank 9. A gas space 15 is formed above the surface of the insulating oil 6 of the tap changer and a communicating pipe 12, which has one opening at a position which is lower than the surface level fluctuating position of the insulating oil 6 and the other opening at a position lower than the surface level fluctuating position of the insulating oil 10 in the tank 9 and communicates the inside of the head section 7 of the tap changer with the inside of the tank 9 through the outside of the transformer is provided.