US4037138A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zero-phase sequence protective device for faults within armature of three-phase synchronous machine
Assignee: Individual
•
Filing: 1975-10-01
•
Granted: 1977-07-19
•
Expires: 1995-10-01
Abstract
Abstract The neutral impedance of a three-phase synchronous machine is so combined with the three-phase, Y-connection protective impedance with the neutral ground connected to a terminal of the synchronous machine that the line current in the branch including a fault may be reduced to zero when a parallel fault occurs within the armature winding, thereby protecting the armature winding and the core of the rotor from burning.
Inventors
- 👤 Koreyasu Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:14
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/08; H02H7/0805
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
141 words
In a three-phase electrical power system, a three-phase synchronous machine having three Y-connected armature windings interconnected at a common point, and a neutral impedance coupling said common point to a neutral point, said windings being connected to corresponding phases of said system; and three protective impedance elements, each element being connected between said neutral point and a corresponding phase of said system, each of said impedance elements having a value such that for each particular phase of said system the values of (i) the zero-phase symmetrical component sequence impedance of the particular armature winding associated with said particular phase, (ii) said neutral impedance, and (iii) the impedance of the protective impedance element connected to said particular phase, combine to provide a series resonant circuit and to exhibit parallel resonance to any fault from said particular armature winding to said neutral point.
Claim 2
Dependent Claim
141 words
In a three-phase electrical power system, a three-phase synchronous machine having three Y-connected armature windings interconnected at a common point, and a neutral impedance coupling said common point to a neutral point, said windings being connected to corresponding phases of said system; and three protective impedance elements, each element being connected between said neutral point and a corresponding phase of said system, each of said impedance elements having a value such that for each particular phase of said system the values of (i) the zero-phase symmetrical component sequence impedance of the particular armature winding associated with said particular phase, (ii) said neutral impedance, and (iii) the impedance of the protective impedance element connected to said particular phase, combine to provide a series resonant circuit and to exhibit parallel resonance to any fault from said particular armature winding to said neutral point.
Claim 3
Dependent Claim
20 words
A zero-phase sequence protective device as set forth in claim 1 wherein each of said protective impedance elements is capacitive.
Claim 4
Dependent Claim
22 words
A zero-phase sequence protective device as set forth in claim 1 wherein said three-phase synchronous machine is a three-phase rotary phase modifier.
Claim 5
Dependent Claim
21 words
A zero-phase sequence protective device as set forth in claim 1 wherein said three-phase synchronous machine is a three-phase synchronous motor.
Claim 6
Dependent Claim
21 words
A zero-phase sequence protective device as set forth in claim 1 wherein said three-phase synchronous machine is a three-phase synchronous generator.
References Cited (Backward Citations)
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US2296109A
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US2824978A
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US3688157A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-18 | 1981-01-17 | 1981-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-18 | 1985-01-17 | 1985-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-18 | 1989-01-17 | 1989-07-19 | $7700.00 | Window Closed / Lapsed |