Starting method for slip-ring induction motor for crane drive

摘要

A procedure for starting the drive for a crane using a slip-ring induction motor uses a resistance in the rotor circuit switched out in discrete steps as the speed rises. With each step on the resistor, the stator voltage is first reduced so that the working point immediately before the switching is maintained. After a given time period, the stator voltage is increased to its original value. The stator voltage is adjusted by an AC regulator with phase control. A speed setpoint can be entered using a master switch. The rotor current is measured and there is a further regulator for this, generating a correction factor for the speed controller.