US3585452A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ground fault protection for ungrounded systems
Assignee: CHALLENGER ACQUISITION Corp
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Filing: 1968-06-03
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Granted: 1971-06-15
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Expires: 1988-06-03
Abstract
Abstract A floating-neutral polyphase distribution system having plural branch lines has ground fault detectors that trip branch-circuit breakers in response to ground faults in different phases of different branch lines. Tripping does not occur in response to a ground fault of a phase in a single branch circuit, but warning signals are provided for such faults.
Inventors
- 👤 Anatole J Goodwin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:52
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/26; H02H3/32; H02H3/34; H02H3/347
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
127 words
In an altErnating-current distribution system, a floatingneutral alternating-current supply line, plural distribution lines extending from said supply line, each said line having plural phase conductors, a circuit interrupter in at least one of said plural distribution lines, and means for controlling said interrupter, said control means including a ground-fault detector of the current-responsive type coupled to said one distribution line, said control means being effective for causing opening of said circuit interrupter only in response to ground-fault current that is substantially greater than the maximum ground-fault current that could result from a single phase-to-ground fault, thereby providing protection against such greater ground-fault current that could develop upon occurrence of concurrent phaseto-ground faults in different phases of said one distribution line and of another of said distribution lines.
Claim 2
Dependent Claim
127 words
In an altErnating-current distribution system, a floatingneutral alternating-current supply line, plural distribution lines extending from said supply line, each said line having plural phase conductors, a circuit interrupter in at least one of said plural distribution lines, and means for controlling said interrupter, said control means including a ground-fault detector of the current-responsive type coupled to said one distribution line, said control means being effective for causing opening of said circuit interrupter only in response to ground-fault current that is substantially greater than the maximum ground-fault current that could result from a single phase-to-ground fault, thereby providing protection against such greater ground-fault current that could develop upon occurrence of concurrent phaseto-ground faults in different phases of said one distribution line and of another of said distribution lines.
Claim 3
Dependent Claim
92 words
Apparatus in accordance with claim 1, further including means connected to said alternating-current supply line for providing an artificial neutral of limited current capacity for all said distribution lines proportioned to suppress the tendency of an ungrounded system to develop large values of phase-to-ground voltage at the unfaulted phases upon occurrence of a phase-to-ground fault, the minumum response level of said control means for causing said circuit interrupter to open being substantially higher than the maximum level of ground-fault current drawn by said artificial neutral means during a single-phase fault to ground.
Claim 4
Dependent Claim
34 words
Apparatus in accordance with claim 1, wherein said alternating-current supply is a three-phase supply and wherein each of said distribution lines includes a current-responsive ground-fault detector and a circuit interrupter controlled thereby as aforesaid.
Claim 5
Dependent Claim
84 words
Apparatus in accordance with claim 1, further including means connected to said alternating-current supply line for providing an artificial neutral of limited current capacity for all said distribution lines effective upon occurrence of a phase-to-ground fault in one of said lines to develop a limited level of ground-fault current, and said control means having a response level effective to cause opening of said one circuit interrupter only at ground fault currents greatly in excess of the ground fault current passed by said artificial neutral.
Claim 6
Dependent Claim
65 words
Apparatus in accordance with claim 1, further including warning means coupled to each of said distribution lines and responsive to an amount of ground-fault current above a threshold that is substantially below the level that is operative to cause opening of said circuit interrupter for indicating the presence of a fault between any one phase and ground in a respective one of said distribution lines.
Claim 7
Dependent Claim
65 words
Apparatus in accordance with claim 4, further including warning means coupled to each of said distribution lines and responsive to an amount of ground-fault current above a threshold that is substantially below the limited level of ground fault current passed by said artificial neutral for indicating the presence of a fault between any one phase and ground in a respective one of said distribution lines.
References Cited (Backward Citations)
US3158785A
Cited
US3356939A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-14 | 1974-12-14 | 1975-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-14 | 1978-12-14 | 1979-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-14 | 1982-12-14 | 1983-06-15 | $7700.00 | Window Closed / Lapsed |