Pt Components, Inc.

Rexnard Corporation

Joseph S Bossi

Victor A Murn

Steven F Chmiel

In an AC motor having a main winding connectable to an AC power source for supplying running torque, and having a start winding connectable to the AC power source for supplying starting torque, a start switch is provided for connecting and disconnecting the start winding from the AC power source in starting and running modes, respectively. A main winding voltage phase detector detects the phase of voltage across the main winding. A start winding current phase detector detects the phase of current through the start winding during the starting mode. A cut-out circuit responds to the main winding voltage phase detector and to the start winding current phase detector.

Phase detector motor start switch

A low cost, low part content single phase AC induction motor control starting circuit is provided which is speed sensitive, load sensitive and AC line voltage fluctuation insensitive. A dual comparator chip (20, 22) senses and compares relative magnitudes of AC line and auxiliary winding voltages (48, 40) to de-energize the auxiliary winding (2) at cut-out speed, and automatically re-energize the auxiliary winding at cut-in speed to accelerate or restart the motor from an overload or stall condition. Hysteresis circuitry (20, 50, 52, 57, 80) provides a lower cut-in speed than cut-out speed. Simplified power supply and voltage detection circuitry is also disclosed.

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West Allis, WI, United States of America

Joseph S Bossi