FIELD: starting and controlling ac drives. SUBSTANCE: voltage changer has three-leg transformer with three secondary windings placed on respective legs and interconnected in star as well as two primary windings interconnected in series opposition and connected in series with supply mains; extreme legs are made of electric steels characterized in that ratio of specific magnetic reluctance to specific ohmic resistance of first extreme leg and ratio of specific magnetic reluctance to specific ohmic resistance of second leg are correlated by definite equation so that magnetic fluxes in extreme legs are relatively shifted 60 deg. apart. EFFECT: enhanced reliability of balanced voltages and stability of time characteristics. 2 dwg
