To perform quick manual operation of tap change by a number of persons smaller than the number of transformers.

Manual operation inputs 1-16 are connected to the load time tap change information of a transformer 67 through relays 17-32, changeover switches S1-S8 are connected with a power supply through first auxiliary relays 33-40 on the side of A bus or second auxiliary relays 41-48 on the side of B bus, a plurality of output auxiliary lines AR-BL are connected with the power supply through relay contacts and first or second auxiliary relay contact, third and fourth auxiliary relays 49-52 and 53-56 are connected in parallel between respective output auxiliary lines AR-BL and the power supply, tap change outputs 57-64 of each transformer are connected with the first or second auxiliary relay contact through third or fourth auxiliary relay contact, and the relay contact is connected directly with the tap change output portions 57-64.