US3660718A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatically resetting motor protection circuit responsive to overcurrent and overtemperature
Assignee: Honeywell Inc
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Filing: 1970-06-08
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Granted: 1972-05-02
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Expires: 1990-06-08
Abstract
Abstract A protection system for hermetic compressors which senses the current being drawn by the compressor motor, and the condition of the motor as a function of a safety switch means which is enclosed within the system or motor. A locked rotor current overload causes immediate operation of the electronics to disconnect the motor from the line. A slowly rising unsafe condition, which is sensed by the opening of the safety switch means, also removes the motor from the line. The electronic circuitry has a time delay discharge network that prevents reclosing the electrical contactor until a sufficient delay has existed for pressures in the compressor system to fall to a safe level.
Inventors
- 👤 Balthasar H Pinckaers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:21
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/08; H02H7/085; H02H3/00; H02H3/02; H02H3/06
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
236 words
A system protection circuit adapted to be connected to an electric motor wherein the system includes safety switch means responsive to a system parameter to protect the system when an unsafe condition exists, including: a series circuit including a primary winding of a current transformer and controllable switch means adapted to connect said motor to a source of voltage; a current transformer secondary winding including first impedance means connected so that a voltage developed across said secondary winding is impressed across said first impedance means; second impedance means connected through said safety switch means in a circuit with said first impedance means when said system is operating normally; circuit means including energy storage means connected to said secondary winding to store electrical energy at a rate governed by said motor operation and the condition of said safety switch means; switching circuit means responsive to said stored electrical energy to operate said controllable switch means to disconnect said electric motor from said source of voltage in the event that said energy storage means stores sufficient energy from said secondary winding; and said switching circuit means further including diode and resistor means connected across said energy storage means to provide a time delay discharge of said energy storage means prior to said switching circuit means automatically resetting after operation of said controllable switch means in the event of said controllable switch means operating due to an unsafe condition.
Claim 2
Independent Claim
236 words
A system protection circuit adapted to be connected to an electric motor wherein the system includes safety switch means responsive to a system parameter to protect the system when an unsafe condition exists, including: a series circuit including a primary winding of a current transformer and controllable switch means adapted to connect said motor to a source of voltage; a current transformer secondary winding including first impedance means connected so that a voltage developed across said secondary winding is impressed across said first impedance means; second impedance means connected through said safety switch means in a circuit with said first impedance means when said system is operating normally; circuit means including energy storage means connected to said secondary winding to store electrical energy at a rate governed by said motor operation and the condition of said safety switch means; switching circuit means responsive to said stored electrical energy to operate said controllable switch means to disconnect said electric motor from said source of voltage in the event that said energy storage means stores sufficient energy from said secondary winding; and said switching circuit means further including diode and resistor means connected across said energy storage means to provide a time delay discharge of said energy storage means prior to said switching circuit means automatically resetting after operation of said controllable switch means in the event of said controllable switch means operating due to an unsafe condition.
Claim 3
Dependent Claim
31 words
A system protection circuit adapted to be connected to an electric motor as described in claim 1 wherein said impedance means are resistors and said energy storage means is a capacitor.
Claim 4
Dependent Claim
39 words
A system protection circuit adapted to be connected to an electric motor as described in claim 2 wherein said switching circuit means includes transistors and connection means to control solid state switch means to operate said controllable switch means.
Claim 5
Dependent Claim
41 words
A system protection circuit adapted to be connected to an electric motor as described in claim 3 wherein said safety switch means is a temperature responsive switch in thermal contact with said electric motor to protect said motor from temperature overloads.
Claim 6
Dependent Claim
43 words
A system protection circuit adapted to be connected to an electric motor as described in claim 4 wherein an electrically conductive shunt is connected across said current transformer primary winding to adjust said protection circuit to the normal current capacity of said motor.
Claim 7
Dependent Claim
39 words
A system protection circuit adapted to be connected to an electric motor as described in claim 1 wherein said switching circuit means includes transistors and connection means to control solid state switch means to operate said controllable switch means.
Claim 8
Dependent Claim
31 words
A system protection circuit adapted to be connected to an electric motor as described in claim 6 wherein said impedance means are resistors and said energy storage means is a capacitor.
Claim 9
Dependent Claim
34 words
A system protection circuit adapted to be connected to an electric motor as described in claim 7 wherein said controllable switch means is an electromagnetic contactor including mechanical contacts to control said electric motor.
Claim 10
Dependent Claim
41 words
A system protection circuit adapted to be connected to an electric motor as described in claim 8 wherein said safety switch means is a temperature responsive switch in thermal contact with said electric motor to protect said motor from temperature overloads.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-02 | 1975-11-01 | 1976-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-02 | 1979-11-01 | 1980-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-02 | 1983-11-01 | 1984-05-02 | $7700.00 | Window Closed / Lapsed |