STARTER FOR WOUND-ROTOR INDUCTION MOTOR

PROBLEM TO BE SOLVED: To prevent occurrence of flashover when a short-circuit collar is removed immediately after stop. SOLUTION: An wound-rotor induction motor 2 comprises a main power supply (not shown), a slip ring (not shown) for short-circuiting the secondary winding, and a brush lifter 4. The starter for the motor 2 comprises a main contactor 1 provided on the primary of the motor 2, a resistor 5 provided on the secondary of the motor 2, a short-circuit contactor 3 provided between the resistor 5 and the secondary of the motor 2, a timer 6 for measuring the stop time of the motor 2, and a control circuit 7 for pulling down a brush upon expiration of the timer 6.