PURPOSE: To enable simplifying terminal treatment operation without losing the economical merit of an aluminum material by using the aluminum material for main winding conductors and a copper material for tap winding conductors.

CONSTITUTION: Main winding conductors 1, 6 are made of an aluminum material and tap winding conductors 22W25 are made of a copper material. For example, winding terminals 22a, 22b are made of the extensions of both the ends of the winding conductor 22 and the other winding terminals 23a, 23bW25b are similarly connected direct to the terminals of a tap switch and are made tap terminals 13W18. For this reason, even if number of tap winding conductors 22W25 increases, the terminal treatment of connecting a compound connecting conductor 8 is only for the terminals 1a, 1b, 6a and 6b of the main windings 1 and 6. The ratio occupied in the total windings by the tap winding conductors 22W25 is also approx. 10W20% and even if the copper material is used for tap winding conductors, the economical merit of using the aluminum material for the main winding conductors 1, 6 is not lost.