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US4080640A
Expired / Lapsed
US
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People-protecting ground fault circuit interrupter
Assignee: Westinghouse Electric Corp
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Filing: 1976-09-27
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Granted: 1978-03-21
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Expires: 1996-09-27
Abstract
Abstract A ground fault circuit interrupter comprises separable contacts for interrupting current flow through a power circuit being protected, trip means operable upon energization to effect separation of the contacts, means for detecting ground fault current, means for monitoring voltage upon the power circuit, and means responsive to the ground fault current detecting means and the voltage monitoring means for energizing the trip means when ground fault current reaches a trip current level. The trip current level varies as a function of the power circuit voltage.
Inventors
- 👤 Robert T. Elms
- 👤 Joseph C. Engel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:45
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/26; H02H3/32; H02H3/33
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
99 words
A ground fault circuit interrupter, comprising: separable contacts for interrupting current flow through a power circuit being protected; trip means operable upon energization to effect separation of said contacts; means for detecting ground fault currents; means for monitoring voltage upon a power circuit being protected; means responsive to said voltage monitoring means for setting a trip current level as a function of said power circuit voltage; and comparator means connected to said ground fault current detecting means and said trip current level setting means for energizing said trip means whenever a ground fault current reaches said trip current level.
Claim 2
Dependent Claim
99 words
A ground fault circuit interrupter, comprising: separable contacts for interrupting current flow through a power circuit being protected; trip means operable upon energization to effect separation of said contacts; means for detecting ground fault currents; means for monitoring voltage upon a power circuit being protected; means responsive to said voltage monitoring means for setting a trip current level as a function of said power circuit voltage; and comparator means connected to said ground fault current detecting means and said trip current level setting means for energizing said trip means whenever a ground fault current reaches said trip current level.
Claim 3
Dependent Claim
80 words
A ground fault circuit interrupter as recited in claim 1, wherein said responsive means sets said trip current level at a first value for all power circuit voltages up to a first predetermined voltage, continuously increases said trip current level for increasing power circuit voltages up to a second predetermined power circuit voltage, and sets said trip current level at a second level higher than said first level for all power circuit voltages above said second predetermined power circuit voltage.
Claim 4
Dependent Claim
49 words
A ground fault circuit interrupter as recited in claim 2, wherein the increase in said trip current level between said first predetermined power circuit voltage and said second predetermined power circuit voltage is approximately proportional to the increase in conductivity of human skin between said two predetermined circuit voltages.
Claim 5
Dependent Claim
59 words
A ground fault circuit interrupter as recited in claim 1, wherein said responsive means sets said trip current level equal to a first value for power circuit voltages up to a predetermined voltage and sets said trip current level equal to a second value higher than first value for all power circuit voltages above said predetermined power circuit voltage.
References Cited (Backward Citations)
US3978400A
Cited
US3976987A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-03-20 | 1981-09-19 | 1982-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-03-20 | 1985-09-19 | 1986-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-03-20 | 1989-09-19 | 1990-03-21 | $7700.00 | Window Closed / Lapsed |