US3683199A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Over-{11 and underexcitation protection circuit for alternating current power systems
Assignee: Westinghouse Electric Corp
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Filing: 1970-09-14
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Granted: 1972-08-08
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Expires: 1990-09-14
Abstract
Abstract Polyphase generators operating in parallel are provided with a circuit to protect against over or under excitation of any one generator. The circuit comprises means for developing a direct voltage proportional to the differential reactive current of each generator and also means for developing a direct voltage proportional to the rectified phase voltages, such voltages being summed and the result compared with a reference.
Inventors
- 👤 William W Billings
- 👤 Wendell Calfee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:12
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/06; H02H7/062
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
104 words
An electrical power system comprising, in combination: a plurality of polyphase alternating current power sources connected in parallel; means for developing for each of said power sources a first direct voltage proportional to the difference between the reactive current of each of said power sources and the average reactive current of the parallel combination of said plurality of power sources; means for developing a second direct voltage proportional to the rectified voltage of said power sources; means for developing a sensing voltage proportional to the sum of said first and second direct voltages; and means for comparing said sensing voltage with a reference voltage.
Claim 2
Dependent Claim
104 words
An electrical power system comprising, in combination: a plurality of polyphase alternating current power sources connected in parallel; means for developing for each of said power sources a first direct voltage proportional to the difference between the reactive current of each of said power sources and the average reactive current of the parallel combination of said plurality of power sources; means for developing a second direct voltage proportional to the rectified voltage of said power sources; means for developing a sensing voltage proportional to the sum of said first and second direct voltages; and means for comparing said sensing voltage with a reference voltage.
Claim 3
Dependent Claim
45 words
The subject matter of claim 1 wherein: said means for comparing said sensing voltage with a reference voltage comprises an overexcitation sensing circuit portion and an underexcitation sensing circuit portion each connected to receive said sensing voltage from said means for developing said sensing voltage.
Claim 4
Dependent Claim
132 words
The subject matter of claim 1 wherein: said means for developing a first direct voltage comprises a demodulation circuit including, pair of terminals for receiving an alternating voltage; a first circuit branch connected between one of said pair of terminals and a common circuit point and comprising a first pair of diodes connected in series by like polarity electrodes thereof; a second circuit branch connected between the other of said pair of terminals and said common circuit point and comprising a second pair of diodes connected in series by like polarity electrodes thereof, said electrodes being of opposite polarity to the interconnected electrodes of said first pair of diodes; and a Zener diode connected from the midpoint between said first pair of diodes and the midpoint between said second pair of diodes.
References Cited (Backward Citations)
US3539820A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-08 | 1976-02-07 | 1976-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-08 | 1980-02-07 | 1980-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-08 | 1984-02-07 | 1984-08-08 | $7700.00 | Window Closed / Lapsed |