US3840783A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System and apparatus for detecting ground faults on ungrounded,polyphase power distribution systems
Assignee: General Electric Co
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Filing: 1973-07-26
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Granted: 1974-10-08
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Expires: 1993-07-26
Abstract
Abstract The disclosure is directed to apparatus for sensing a ground fault in a normally ungrounded, polyphase power distribution system. One of the phase lines is coupled to ground through a first inductor which is transformer coupled with a second inductor connected across two other phase lines. A current sensor responses to current flow in the ground circuit including the first inductor resulting from a ground fault on any of the phase lines by signaling a ground fault relay to either provide a fault indication, interrupt the ground circuit or interrupt the phase lines. A system of ground fault sensors and signal interlocked ground fault relays operating in a multi-zone power distribution system is also disclosed.
Inventors
- 👤 G Eckart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:51
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/16; H02H3/162; H02H3/165
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
106 words
Apparatus for detecting ground faults in a normally ungrounded polyphase electrical power distribution system fed by a delta-connected source, said apparatus comprising, in combination: A. a circuit path for electrically coupling one of the phase conductors of the delta-connected source to ground; B. a first inductor serially included in said circuit path; C. a second inductor transformer coupled with said first inductor, said second inductor adapted for electrical connection between two other phase conductors of the deltaconnected source; and D. means including a sensor coupled with said circuit path for detecting current flow therethrough resulting from a ground fault on any one of the phase conductors.
Claim 2
Dependent Claim
106 words
Apparatus for detecting ground faults in a normally ungrounded polyphase electrical power distribution system fed by a delta-connected source, said apparatus comprising, in combination: A. a circuit path for electrically coupling one of the phase conductors of the delta-connected source to ground; B. a first inductor serially included in said circuit path; C. a second inductor transformer coupled with said first inductor, said second inductor adapted for electrical connection between two other phase conductors of the deltaconnected source; and D. means including a sensor coupled with said circuit path for detecting current flow therethrough resulting from a ground fault on any one of the phase conductors.
Claim 3
Dependent Claim
18 words
The apparatus dEfined in claim 1, which further includes a current limiter serially included in said circuit path.
Claim 4
Dependent Claim
33 words
The apparatus defined in claim 2, which further includes a voltmeter connected across said current limiter to provide a reading indicative of which one of the phase conductors is experiencing a ground fault.
Claim 5
Dependent Claim
26 words
The apparatus defined in claim 1 wherein the transformer coupling between said second inductor and said first inductor is on the order of two to one.
Claim 6
Dependent Claim
18 words
The apparatus defined in claim 1, which further includes ground fault relay connected to respond to said sensor.
Claim 7
Dependent Claim
31 words
The apparatus defined in claim 5, which further includes a circuit breaker controlled by said ground fault relay to open the phase conductors upon the existence of a ground fault thereon.
Claim 8
Dependent Claim
47 words
The apparatus defined in claim 5, which further includes normally closed circuit interrupter contacts serially connected in said circuit path, said interrupter contacts being operated by said fault relay to open said circuit path upon the existence of a ground fault on one of the phase conductors.
Claim 9
Dependent Claim
33 words
The apparatus defined in claim 5, which further includes signaling means connected to be activated by said ground fault relay upon the existence of a ground fault on one of the phase conductors.
Claim 10
Independent Claim
227 words
A system for detecting ground faults on an ungrounded, multizone, three-phase power distribution system including main and feeder buses, said ground fault detecting system comprising: A. a circuit path electrically coupling one of the main buses to ground; B. a first inductor serially included in said circuit path; C. a second inductor transformer coupled with said first inductor, said second inductor electrically connected between the other two of the main buses; D. a current sensor coupled with said circuit path for detecting current flow therethrough resulting from a downstream ground fault on the distribution system; E. a main ground fault relay activated by said current sensor to issue a first control signal in the event of a downstream ground fault; F. first means responsive to said first control signal; G. a zero sequence current transformer coupled with the feeder buses connected from the main buses to sense a downstream ground fault; H. a feeder ground fault relay activated by said current transformer to issue a second control signal in the event of a downstream ground fault; I. second means responsive to said second control signal; and J. signaling means interconnecting said feeder ground fault relay and said main ground fault relay for imposing a restraint on the issuance of said first control signal in the event of a ground fault sensed on one of the feeder buses.
Claim 11
Independent Claim
227 words
A system for detecting ground faults on an ungrounded, multizone, three-phase power distribution system including main and feeder buses, said ground fault detecting system comprising: A. a circuit path electrically coupling one of the main buses to ground; B. a first inductor serially included in said circuit path; C. a second inductor transformer coupled with said first inductor, said second inductor electrically connected between the other two of the main buses; D. a current sensor coupled with said circuit path for detecting current flow therethrough resulting from a downstream ground fault on the distribution system; E. a main ground fault relay activated by said current sensor to issue a first control signal in the event of a downstream ground fault; F. first means responsive to said first control signal; G. a zero sequence current transformer coupled with the feeder buses connected from the main buses to sense a downstream ground fault; H. a feeder ground fault relay activated by said current transformer to issue a second control signal in the event of a downstream ground fault; I. second means responsive to said second control signal; and J. signaling means interconnecting said feeder ground fault relay and said main ground fault relay for imposing a restraint on the issuance of said first control signal in the event of a ground fault sensed on one of the feeder buses.
Claim 12
Dependent Claim
47 words
The ground fault detecting system defined in claim 9, wherein said first responsive means is a main circuit breaker for interrupting power in said main buses and said main buses and said second responsive means is a feeder circuit breaker for interrupting power in said feeder buses.
Claim 13
Dependent Claim
41 words
The ground fault detecting system defined in claim 9, wherein said first and second responsive means comprise a common trip coil operating to open interrupter contacts in said circuit path in response to either of said first and second control signals.
Claim 14
Dependent Claim
20 words
The ground fault detecting system defined in claim 9, wherein said first and second responsive means comprise separate signal indicators.
Claim 15
Dependent Claim
123 words
The ground fault detection system defined in claim 9, wherein the distribution system includes branch buses connected from the feeder buses, said ground fault detecting system further including: A. branch zero sequence current transformer coupled with the branch buses to sense a downstream ground fault; B. a branch ground fault relay activated by said branch current transformer to issue a third control signal in the event of a downstream ground fault; C. third means responsive to said third control signal; and D. second signaling means interconnectIng said branch ground fault relay and said feeder ground fault relay to impose a restraint on the issuance of said second control signal in the event of a ground fault sensed on one of the branch buses.
Claim 16
Dependent Claim
59 words
The ground fault detection system defined in claim 13, wherein said first responsive means is a main circuit breaker for interrupting power on the main buses, said second responsive means is a feeder circuit breaker for interrupting power on the feeder buses, and said third responsive means is a branch circuit breaker for interrupting power on the branch buses.
Claim 17
Dependent Claim
43 words
The ground fault detection system defined in claim 13, wherein said first, second and third responsive means comprise a common trip coil operating to open interrupter contacts in said circuit path in response to either of said first, second and third control signals.
Claim 18
Dependent Claim
21 words
The ground fault detection system defined in claim 13, wherein said first, second and third responsive means comprise separate signal indicators.
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) | 1977-10-07 | 1978-04-08 | 1978-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-07 | 1982-04-08 | 1982-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-07 | 1986-04-08 | 1986-10-08 | $7700.00 | Window Closed / Lapsed |