PURPOSE: To give high acceleration to a plunger and reduce current loss by a method wherein the current is supplied to a solenoid while the phase of AC voltage is on the midway of the positive half-wave and on the negative half-wave which follows that positive half-wave.

CONSTITUTION: A control circuit is composed of a solenoid 7 which moves a plunger with a relatively large stroke, a trigger pulse generating circuit 3 which generates a trigger pulse synchronized with the adequate phase of the AC voltage, a three-terminal two-way thyristor 5 which is used to start the current application to the solenoid, a trigger circuit 4 which controls the turn-on of the three-terminal two-way thyristor 5, an exciting finishing phase control circuit 6 which controls the turn-off of the three-terminal two-way thyristor 5 and a full- wave rectifying circuit 2. And the current is supplied to the solenoid while the phase of the AC voltage is on the midway of the positive half-wave and on the negative half-wave which follows that positive half-wave.