TAP CHANGER DURING UNDER-LOAD

PROBLEM TO BE SOLVED: To provide an under-load tap changer wherein sticking and deposition of carbon and metal powder is reduced to a minimum. SOLUTION: A shield part 3 and a drive mechanism 6 for driving the shield part 3 are provided at a lower part and an upper part in an opening/closing changer oil bath 1, respectively, the shield part 3 is connected to the drive mechanism 6 with an insulating cylinder 2, a dirt oil in the oil bath 1 is sucked up from a bottom part side in the oil bath 1, which is supplied to a purifying device set outside the oil bath 1 for purification, and a purified insulating oil 7 is supplied to the oil bath 1 from the upper part side of the oil bath 1. Here, an oil convection preventing member (insulating shields 8a-8c) is provided, so that the purified insulating oil 7 is guided to an outer peripheral part of the shield part 3, through the outer peripheral part of the drive mechanism 6 and that of the insulating cylinder.