Electric refrigeration and air-conditioning protection circuit

Claim 1

A control circuit for a refrigeration system having an electric motor driven refrigerant compressor comprising, a first source of relatively high voltage electric current adapted for energizing said compressor motor, a second source of relatively low voltage electric current adapted for control purposes, a contactor having normally open contacts and a coil to be energized to close its normally open contacts, means connecting said compressor motor in series with said normally open contacts to said first source, a control switch and a normally open timer switch connected in series with said second source and said contactor coil to energize said contactor coil when all of said switches are closed, an electric timer motor, means responsive to connect and energize to operate said timer motor from one of said sources only when said compressor motor is not energized, and means connecting said timer motor shaft to said timer switch in a manner to momentarily close said normally open timer switch at predetermined spaced time intervals during operation of said timer motor whereby to energize said contactor coil and said compresSor motor when both said timer and control switch are closed, said timer motor being subsequently reenergized to open said timer switch and prevent a subsequent reenergization of said contactor coil and compressor motor until at least a predetermined time interval after said compressor motor has been deenergized responsive to opening of any of said series connected switches.