PURPOSE: To sufficiently resist electromagnetic mechanical force in case of the formation of short-circuit current, by varying the arrangement of each wound conductor.

CONSTITUTION: Taps P2, P1 connected to a polarity changer So of a tap changer when loading among the taps of a tap winding 3 are arranged in the outermost side P2 and the inside P1 next to the P2, and tap conductors are successively placed in the separating direction from the changer So in proportional to advance to the inside. When there happen accidents at a terminal 6 under this condition, short- circuit current flows between taps P2-T5 and this device is subject to great electromagnetic mechanical force, but there are the conductors of taps T1, T8, T2, T7...T5 and the conductors of eight wires, and this device leans on these conductors. That is, force received by one conductor is received by all nine conductors, thus ensuring the winding with sufficient strength.