PURPOSE: To reduce a noise level and make easy the transportation of the titled device by such an arrangement that the windings facing to the tank wall are connected so that the lower side of tank becomes low voltage, reducing the size of insulator between the tank and lower windings and providing a noise shielding wall at the side surface of lower side of tank.

CONSTITUTION: In a large capacity transformer, a high voltage winding 17 is connected directly to the ground system. Therefore, the multistage insulation system is employed for the insulation of such transformer and the neutral point terminal O is set to the lower insulation class as compared with the line terminal U. For example, in case the line terminal U is set to #200, the neutral point 0 is set to #60. The required insulation size for winding 17 and wall of tank 1 is determined by the potential of winding. Therefore, with such connection as shown in the figure, the insulation size D in the side of neutral point (low voltage side) can be set smaller than the size C between the wiring 17 and wall of tank 1 at the line end. Employment of such high voltage winding structure makes it possible that the lower side of insulation size between the winding 17 and wall of tank 1 can be reduced smaller than the upper side of winding. Thereby, a side plate of tank 1 can be moved near to the side of winding 17 by bending the plate only by the size E and a noise shielding wall 24 can be provided in such space.