US3742302A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Motor relay protection for refrigerant compressor motors
Assignee: Carrier Corp
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Filing: 1971-10-12
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Granted: 1973-06-26
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Expires: 1991-10-12
Abstract
Abstract A refrigerant compressor motor is provided with a motor protection and control system providing various motor control functions in response to motor current, refrigeration system temperature, thermostat contact opening and closing and motor relay solenoid current. A resistor in series with the motor relay solenoid provides a voltage drop signal which is integrated to provide a control signal to a trip circuit which, in turn, deenergizes the motor relay in the event that the integrated relay current signal exceeds a predetermined trip threshold magnitude. If the solenoid current drops to a normal value after being initially energized, the integrator output remains below the trip threshold and the solenoid remains energized. In the event that the solenoid current fails to drop to a normal operating value after a period of time, the integrator output rises to a level which exceeds the trip level and de-energizes the solenoid. Additional time delay means is provided so that a period of time must elapse before the solenoid can be reenergized to permit it to cool.
Inventors
- 👤 D Neill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:07
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/22; H02H7/222; H02H7/08
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
325 words
A control system for the compressor motor of a refrigeration system comprising: A. a relay having a relay solenoid controlling electrical contacts for connecting and disconnecting said compressor motor with a source of electric current; B. solid state switch means controlling the energizing and deenergizing of said relay solenoid; C. relay current sensing means connected to provide a relay solenoid current signal responsive to the magnitude of current drawn by the relay solenoid; D. a first trip circuit having a trip level for rendering said switch means nonconducting in response to an input signal of a predetermined magnitude being supplied thereto; E. integration circuit means for integrating the relay current signal from the relay current sensing means, and for supplying the integrated output signal to said first trip circuit, the integration function being selected so that in the event the initial relay current is reduced to a normal level after a period of time, the output signal level from the integration circuit will be below said trip level, but in the event that an abnormally high relay solenoid current continues for an excessive period of time, the integrated output signal will reach the trip level of said first trip circuit and de-energize said relay by actuating said switch means to the nonconducting state to protect the relay solenoid; F. compressor motor current sensing means and a second trip circuit responsive to the magnitude of the sensed compressor motor current connected for actuating said switch means to the nonconducting state upon the occurrence of an excess motor current condition; G. reset time delay means for resetting said second trip circuit after a period of time subsequent to a trip thereof; and H. feedback means for tripping said second trip circuit upon actuating of said switch means to the nonconducting state so that the reset time delay associated with the second trip circuit is imposed on the system when it is tripped by the first trip circuit.
Claim 2
Dependent Claim
325 words
A control system for the compressor motor of a refrigeration system comprising: A. a relay having a relay solenoid controlling electrical contacts for connecting and disconnecting said compressor motor with a source of electric current; B. solid state switch means controlling the energizing and deenergizing of said relay solenoid; C. relay current sensing means connected to provide a relay solenoid current signal responsive to the magnitude of current drawn by the relay solenoid; D. a first trip circuit having a trip level for rendering said switch means nonconducting in response to an input signal of a predetermined magnitude being supplied thereto; E. integration circuit means for integrating the relay current signal from the relay current sensing means, and for supplying the integrated output signal to said first trip circuit, the integration function being selected so that in the event the initial relay current is reduced to a normal level after a period of time, the output signal level from the integration circuit will be below said trip level, but in the event that an abnormally high relay solenoid current continues for an excessive period of time, the integrated output signal will reach the trip level of said first trip circuit and de-energize said relay by actuating said switch means to the nonconducting state to protect the relay solenoid; F. compressor motor current sensing means and a second trip circuit responsive to the magnitude of the sensed compressor motor current connected for actuating said switch means to the nonconducting state upon the occurrence of an excess motor current condition; G. reset time delay means for resetting said second trip circuit after a period of time subsequent to a trip thereof; and H. feedback means for tripping said second trip circuit upon actuating of said switch means to the nonconducting state so that the reset time delay associated with the second trip circuit is imposed on the system when it is tripped by the first trip circuit.
Claim 3
Dependent Claim
340 words
A control system for the compRessor motor of a refrigeration system comprising: A. a relay having a relay solenoid controlling electrical contacts for connecting and disconnecting said compressor motor with a source of electric current; B. solid state switch means controlling the energizing and de-energizing of said relay solenoid; C. relay current sensing means connected to provide a relay solenoid current signal responsive to the magnitude of current drawn by the relay solenoid; D. a relay overload trip circuit associated with said relay current sensing means and having a trip level for rendering said switch means nonconducting in response to a relay solenoid current overload condition; E. integration circuit means for integrating the relay current signal from the relay current sensing means, and for supplying the integrated output signal to said relay overload trip circuit, the integration function being selected so that in the event the initial relay current is reduced to a normal level after a period of time, the output signal level from the integration circuit will be below said trip level, but in the event that an abnormally high relay solenoid current continues for an excessive period of time, the integrated output signal will reach the trip level of said to-relay overload-trip circuit and de-energize said relay by actuating said switch means to the nonconducting state to protect the relay solenoid; F. compressor motor overload sensing means connected for providing a motor overload current signal responsive to a motor overload condition; G. a motor overload trip circuit associated with said relay current sensing means for rendering said switch means nonconducting in response to a motor overload condition; and H. reset time delay means for maintaining said switch means nonconducting for a period of time subsequent to the switch being rendered nonconducting due to an overload condition sufficient to actuate either of said trip circuits, whereby said reset time delay is imposed on re-energizing both said compressor motor and said relay solenoid if either experiences a sensed overload condition of a magnitude sufficient to trip the control system.
Claim 4
Dependent Claim
340 words
A control system for the compRessor motor of a refrigeration system comprising: A. a relay having a relay solenoid controlling electrical contacts for connecting and disconnecting said compressor motor with a source of electric current; B. solid state switch means controlling the energizing and de-energizing of said relay solenoid; C. relay current sensing means connected to provide a relay solenoid current signal responsive to the magnitude of current drawn by the relay solenoid; D. a relay overload trip circuit associated with said relay current sensing means and having a trip level for rendering said switch means nonconducting in response to a relay solenoid current overload condition; E. integration circuit means for integrating the relay current signal from the relay current sensing means, and for supplying the integrated output signal to said relay overload trip circuit, the integration function being selected so that in the event the initial relay current is reduced to a normal level after a period of time, the output signal level from the integration circuit will be below said trip level, but in the event that an abnormally high relay solenoid current continues for an excessive period of time, the integrated output signal will reach the trip level of said to-relay overload-trip circuit and de-energize said relay by actuating said switch means to the nonconducting state to protect the relay solenoid; F. compressor motor overload sensing means connected for providing a motor overload current signal responsive to a motor overload condition; G. a motor overload trip circuit associated with said relay current sensing means for rendering said switch means nonconducting in response to a motor overload condition; and H. reset time delay means for maintaining said switch means nonconducting for a period of time subsequent to the switch being rendered nonconducting due to an overload condition sufficient to actuate either of said trip circuits, whereby said reset time delay is imposed on re-energizing both said compressor motor and said relay solenoid if either experiences a sensed overload condition of a magnitude sufficient to trip the control system.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |