Patent US3686552A successfully refreshed from Google Patents.
US3686552A
Expired / Lapsed
US
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Synchronous motor field regulator control
Assignee: Westinghouse Electric Corp
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Filing: 1971-07-30
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Granted: 1972-08-22
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Expires: 1991-07-30
Abstract
Abstract A synchronous motor field regulator system which regulates for a specific power factor within a predetermined line voltage band, providing that a minimum excitation requirement for the load on the synchronous motor is met, and incorporating means for varying the saturation level of a line voltage controller in the regulator as a function of the average synchronous motor field current whereby the synchronous motor average field current on a duty cycle basis will not exceed its rated value. This prevents the line voltage controller in a synchronous motor field regulator from calling for an average synchronous field current greater than the rated synchronous motor field current and protects the synchronous motor and its field exciter against a thermal overload condition when the synchronous motor voltage has dipped for a long period of time and the line voltage regulator is trying to maintain nominal line voltage.
Inventors
- 👤 Robert S Peterson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:21
CPC Classifications
H; H02; H02P; H02P23/00; H02P23/26
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
147 words
In apparatus for varying the field current of a synchronous motor to vary the motor capacitive kilovars and correct for line voltage drops caused by a fluctuating power and inductive kilovar demand, the combination of means for producing a first electrical signal which varies as a function of the actual current supplied to the field winding of said motor, means for producing a second electrical signal which varies as a function of the line voltage supplied to said motor, line voltage control means responsive to said second electrical signal for varying said field current to maintain the line voltage supplied to said motor between predetermined minimum and maximum values, and means responsive to said first electrical signal for regulating the maximum output of said line voltage control means such that the synchronous motor average field current on a duty cycle basis will not exceed its rated value.
Claim 2
Dependent Claim
147 words
In apparatus for varying the field current of a synchronous motor to vary the motor capacitive kilovars and correct for line voltage drops caused by a fluctuating power and inductive kilovar demand, the combination of means for producing a first electrical signal which varies as a function of the actual current supplied to the field winding of said motor, means for producing a second electrical signal which varies as a function of the line voltage supplied to said motor, line voltage control means responsive to said second electrical signal for varying said field current to maintain the line voltage supplied to said motor between predetermined minimum and maximum values, and means responsive to said first electrical signal for regulating the maximum output of said line voltage control means such that the synchronous motor average field current on a duty cycle basis will not exceed its rated value.
Claim 3
Dependent Claim
49 words
The apparatus of claim 1 wherein said line voltage control means comprises a saturable operational amplifier and wherein the means for regulating the maximum output of said line voltage control means varies the saturation level of said operational amplifier as a function of the synchronous motor average field current.
Claim 4
Dependent Claim
59 words
The apparatus of claim 2 wherein said means for regulating the maximum output of said line voltage control means comprises an integrating operational amplifier which integrates the difference between actual synchronous motor field current and the rated value of field current and compares the integrated difference between maximum permissible field current and minimum field current for the synchronous motor.
Claim 5
Dependent Claim
42 words
The apparatus of claim 3 wherein said integrating operational amplifier is saturable and wherein the saturation limit of the saturable operational amplifier is set proportionally to a predetermined maximum field current of the synchronous motor minus the rated synchronous motor field current.
Claim 6
Dependent Claim
46 words
The combination of claim 4 including means for comparing the output of said line voltage control means with said first electrical signal and with an electrical signal proportional to predetermined minimum field current through said synchronous motor to derive an error signal for controlling field current.
Claim 7
Dependent Claim
50 words
The apparatus of claim 4 wherein said saturation limit of said integrating operational amplifier is determined by means of a limiter connected in shunt with said amplifier, and including potentiometers connected to said limiter and adjustable to said predetermined maximum field current and rated field current for the synchronous motor.
Claim 8
Dependent Claim
37 words
The apparatus of claim 6 wherein the output of said line voltage control means is an electrical signal which varies As a function of desired field current to maintain line voltage between predetermined minimum and maximum values.
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) | 1975-08-22 | 1976-02-21 | 1976-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-22 | 1980-02-21 | 1980-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-22 | 1984-02-21 | 1984-08-22 | $7700.00 | Window Closed / Lapsed |