PURPOSE: To improve the reliability of an apparatus by causing the turn ratios of respective windings to coincide with those of a transformer and the direction of a magnetomotive force generated by electric currents flowing through respective windings to relatively coincide with that of the windings of the transformer, by arranging respective windings in a magnetically close manner and by setting the value of self- reactance of respective windings at a predetermined value.

CONSTITUTION: When the turn ratios of respective windings 5, 6 of an exciting rush- current suppressing reactor 4 are caused to coincide with the turn ratio of a transformer 1, the current values i1, i2 of respective windings 5, 6 coincide with electric currents i1, i2 flowing through the corresponding windings 2, 3 with respective degrees of the transformer 1 so that the ratio of the magnetomotive force of respective windings 5, 6 coincides with that of the transformer 1. When the direction of the magnetomotive force generated by the electric currents i1, i2 flowing through respective windings 5, 6 is caused to relatively coincide with that of the windings 2, 3 of the transformer 1, the voltage drop at a stationary time, when the load current of the reactor 4 flows, is caused by a leakage reactance. Also, when respective windings 5, 6 are arranged like the transformer 1 in a magnetically close manner, the leakage reactance is reduced to a small value.