Patent US3673488A successfully refreshed from Google Patents.
US3673488A
Expired / Lapsed
US
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Rotating alternator current generator system
Assignee: General Electric Co
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Filing: 1971-05-17
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Granted: 1972-06-27
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Expires: 1991-05-17
Abstract
Abstract The invention relates to rotating alternating current generator systems. Generator excitation is normally controlled by varying the field current to the exciter. An SCR rectifier circuit responsive to exciter output voltage normally provides controlled direct current for the exciter field while a diode rectifier circuit responsive to exciter output current provides direct current only during transient conditions when the exciter voltage may be low. The current boost diode rectifier circuit is coupled to current transformers located in the exciter output lines. The current boost circuit including the current transformers is designed to take advantage of the characteristic of most alternators that its short-circuit excitation requirement is considerably less than its rated-load excitation requirement, for the same alternator line current. Some exciters, notably salientpole alternators, do not have the large separation between the short-circuit excitation condition and the rated-load excitation condition. Thus, it is difficult to design current transformers with a ratio low enough to insure that the current boost circuit will be regenerative under short-circuit conditions, and yet with a ratio high enough so that the current fed back will not interfere with the exciter field current supplied by the SCR circuit under normal operating conditions. A static switch, of unique design, is provided to insure compatibility between the SCR circuit and the diode rectifier circuit under normal operation, and yet permit the current feedback to be sufficient to support an exciter short circuit, regardless of the separation between the short circuit and rated-load circuit excitation conditions.
Inventors
- 👤 Willaim H Spiller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 04:59
CPC Classifications
H; H02; H02P; H02P9/00; H02P9/10; H02P9/105; H02P9/14; H02P9/36; Y; Y10; Y10S; Y10S322/00; Y10S322/02
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
349 words
In combination, a generator including a field for providing an output voltage at its output terminals in accordance with the current in its field, an exciter including a field connected to supply current from its output terminals to the generator field in accordance with the current in the exciter field, regulator means responsive to the amplitude of said generator output voltage for providing a first control signal, full wave SCR rectifying means energized with the voltage developed at said exciter output terminals and responsive to said first control signal for supplying DC current to said exciter field, said generator responsive to a fault developed at said generator output for introducing an undesirable current in said generator field, said undesirable current operating to reduce the exciter output voltage to a low value and thereby reduce the exciter field current supplied by said SCR rectifier means to a low value, current boost means operative during said undesired current condition for boosting current to said exciter field, said current boost means comprising a diode rectifier means in series with said SCR rectifier means and said exciter field, current transformers located in said exciter output and responsive to the exciter output current during the undesired current condition for supplying current through said diode rectifier means to said exciter field to maintain exciter field current during the fault condition, an SCR circuit connected in parallel across said diode rectifier means, means for normally short circuiting said diode rectifier means comprising a saturable transformer and linear reactor circuit responsive to the AC exciter output voltage for providing a second control signal of substantially constant amplitude to said SCR circuit over the normal range of exciter output voltage but responsive to the exciter output voltage falling below a given threshold level during the undesirable current condition for modifying said second control signal, said SCR circuit responsive to said modified second control signal for unshorting said diode rectifiEr means, said exciter field responsive through said unshorted diode rectifier means to the exciter output current for providing field excitation for said exciter until the fault condition is removed.
Claim 2
Dependent Claim
349 words
In combination, a generator including a field for providing an output voltage at its output terminals in accordance with the current in its field, an exciter including a field connected to supply current from its output terminals to the generator field in accordance with the current in the exciter field, regulator means responsive to the amplitude of said generator output voltage for providing a first control signal, full wave SCR rectifying means energized with the voltage developed at said exciter output terminals and responsive to said first control signal for supplying DC current to said exciter field, said generator responsive to a fault developed at said generator output for introducing an undesirable current in said generator field, said undesirable current operating to reduce the exciter output voltage to a low value and thereby reduce the exciter field current supplied by said SCR rectifier means to a low value, current boost means operative during said undesired current condition for boosting current to said exciter field, said current boost means comprising a diode rectifier means in series with said SCR rectifier means and said exciter field, current transformers located in said exciter output and responsive to the exciter output current during the undesired current condition for supplying current through said diode rectifier means to said exciter field to maintain exciter field current during the fault condition, an SCR circuit connected in parallel across said diode rectifier means, means for normally short circuiting said diode rectifier means comprising a saturable transformer and linear reactor circuit responsive to the AC exciter output voltage for providing a second control signal of substantially constant amplitude to said SCR circuit over the normal range of exciter output voltage but responsive to the exciter output voltage falling below a given threshold level during the undesirable current condition for modifying said second control signal, said SCR circuit responsive to said modified second control signal for unshorting said diode rectifiEr means, said exciter field responsive through said unshorted diode rectifier means to the exciter output current for providing field excitation for said exciter until the fault condition is removed.
Claim 3
Dependent Claim
276 words
In combination, a generator including a field, an exciter having a field for energizing said generator field, first means responsive to the output of said generator for providing a first control signal, second means responsive to said first control signal for energizing said exciter field, said generator responsive to a fault developed at said generator output for introducing an undesirable current in said generator field, said undesirable current operating to modify the exciter output voltage to an undesirable value and thereby modify the exciter field current supplied by said second means to an undesirable value, current boost means operative during said undesired current condition for boosting current to said exciter field, said current boost means comprising a third means in series with said second means and said exciter field, current transformers responsive to the exciter output current during the undesired current condition for supplying current through said third means to said exciter field to maintain exciter field current during the fault condition, fourth means coupled in parallel across said third means, means for normally short circuiting said third means comprising a saturable transformer and linear reactor circuit responsive to the AC exciter output voltage for providing a second control signal of substantially constant amplitude to said fourth means over the normal range of exciter output voltage but responsive to the exciter output voltage falling below a given threshold level during the undesirable current condition for modifying said second control signal, said fourth means responsive to said modified second control signal for unshorting said third means, said exciter field responsive through said unshorted fourth means to the exciter output current for providing field excitation for said exciter.
Claim 4
Dependent Claim
276 words
In combination, a generator including a field, an exciter having a field for energizing said generator field, first means responsive to the output of said generator for providing a first control signal, second means responsive to said first control signal for energizing said exciter field, said generator responsive to a fault developed at said generator output for introducing an undesirable current in said generator field, said undesirable current operating to modify the exciter output voltage to an undesirable value and thereby modify the exciter field current supplied by said second means to an undesirable value, current boost means operative during said undesired current condition for boosting current to said exciter field, said current boost means comprising a third means in series with said second means and said exciter field, current transformers responsive to the exciter output current during the undesired current condition for supplying current through said third means to said exciter field to maintain exciter field current during the fault condition, fourth means coupled in parallel across said third means, means for normally short circuiting said third means comprising a saturable transformer and linear reactor circuit responsive to the AC exciter output voltage for providing a second control signal of substantially constant amplitude to said fourth means over the normal range of exciter output voltage but responsive to the exciter output voltage falling below a given threshold level during the undesirable current condition for modifying said second control signal, said fourth means responsive to said modified second control signal for unshorting said third means, said exciter field responsive through said unshorted fourth means to the exciter output current for providing field excitation for said exciter.
References Cited (Backward Citations)
US3564391A
Cited
US3619761A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-27 | 1975-12-27 | 1976-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-27 | 1979-12-27 | 1980-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-27 | 1983-12-27 | 1984-06-27 | $7700.00 | Window Closed / Lapsed |