METHOD AND SYSTEM FOR CONTROLLING MULTIPLE SPEED MOTOR

摘要

A control system for a multiple speed motor includes a motor circuit having a plurality of resistance varying units in series with the field winding and armature of the motor and separate control circuits for each of the resistance varying units. Each control circuit includes an energizable contactor in series with a gating element and a timer for activating the gating element. The control system includes an activating circuit for bypassing the timer when the level of current flow in the motor circuit is below a certain value. The activating circuit includes a comparator for receiving a reference signal and a signal indicating the level of current flow in the motor circuit and produces an output signal when the current flow is below a certain value which is fed to an OR-gate that also receives a signal from the timer to activate the gating element when either signal is present.