Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1981-11-02
1983-08-16
Smith, Jr., David
Electricity: motive power systems
Induction motor systems
Primary circuit control
318817, H02P 144
Patent
active
043993940
ABSTRACT:
An electronic circuit for automatically disconnecting a start winding of an electric motor after a predetermined time delay is suitable for use in instantly reversing applications and provides timed disconnection of the start winding upon substantially instantaneous reconnection of the motor for reverse rotation. The circuit includes a triac and full wave bridge, the full wave bridge providing full wave rectified D-C to a timing circuit and a resetting circuit. The resetting circuit utilizes a PUT which switches at the gate lead of an SCR in the timing circuit to de-energize it and permit discharge of the timing voltage accumulated during a timed start cycle. A capacitor and resistor in series with the PUT maintain the current therethrough to prevent turn-off during the valley portion of the rectified D-C supply. The entire circuit may be conveniently mounted on a small PC board which fits into the capacitor conduit box mounted to the motor housing, with quick disconnect terminals providing easy installation, maintenance and trouble shooting.
REFERENCES:
patent: 3777232 (1973-12-01), Woods et al.
patent: 3819994 (1974-06-01), Ballman
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