US3895263A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Grounded neutral detector drive circuit for two pole ground fault interrupter
Assignee: ITE Imperial Corp
•
Filing: 1974-08-27
•
Granted: 1975-07-15
•
Expires: 1994-08-27
Abstract
Abstract A ground fault detector for a three-wire single phase A.C. system including protector means to maintain level of performance in the event the neutral is grounded on the load side of the detector is provided with solid state switching means which maintains the protector means energized so long as at least one hot wire of the A.C. system is energized.
Inventors
- 👤 William R Clark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:51
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/16; H02H3/17; H02H3/26; H02H3/32; H02H3/33; H02H3/331
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
196 words
Ground fault detector-interrupter means for a single phase three-wire system having first and second hot conductors at opposite potential with respect to a common neutral conductor grounded at the source energizing said system; said detectorinterrupter means including a differential transformer having first, second, and third primaries connected in series with the first, second, and said ground conductors, respectively, and a secondary wherein net flux generated by unbalanced currents in said primaries induce a fault signal interrupter means in series with said first and second conductors, amplifier means connected between said secondary and said interrupter means to actuate the latter for opening at least one of said hot conductors when said fault signal is of a predetermined characteristic; protector means to maintain performance of said differential transformer in the event the neutral conductor becomes grounded near a load energized by said system; circuit means providing energizing connections between said protector means and both of said hot conductors; said circuit means normally connecting said protector means for energization from said first hot conductor, and additional means to automatically switch energization of said protector means to said second hot wire in the event said first hot wire becomes deenergized.
Claim 2
Dependent Claim
196 words
Ground fault detector-interrupter means for a single phase three-wire system having first and second hot conductors at opposite potential with respect to a common neutral conductor grounded at the source energizing said system; said detectorinterrupter means including a differential transformer having first, second, and third primaries connected in series with the first, second, and said ground conductors, respectively, and a secondary wherein net flux generated by unbalanced currents in said primaries induce a fault signal interrupter means in series with said first and second conductors, amplifier means connected between said secondary and said interrupter means to actuate the latter for opening at least one of said hot conductors when said fault signal is of a predetermined characteristic; protector means to maintain performance of said differential transformer in the event the neutral conductor becomes grounded near a load energized by said system; circuit means providing energizing connections between said protector means and both of said hot conductors; said circuit means normally connecting said protector means for energization from said first hot conductor, and additional means to automatically switch energization of said protector means to said second hot wire in the event said first hot wire becomes deenergized.
Claim 3
Dependent Claim
46 words
Ground fault detector-interrupter means as set forth in claim 1 in which the protector means includes an auxiliary transformer having an auxiliary secondary in series with the neutral conductor and an auxiliary primary connected from said neutral conductor through said circuit means to said hot conductors.
Claim 4
Dependent Claim
129 words
Ground fault detector-interrupter means as set forth in claim 1 in which the circuit means also includes primary and alternate current paths between said protector means and said first and second conductors, respectively; a shunt path connected to said alternate path and said neutral conductor; said shunt path including solid state switching means having a control electrode connected in said primary current path whereby said switching means is conducting when said first conductor is energized and is blocking when said first conductor is deenergized; with said switching means conducting said shunt path being closed whereby current in said alternate path bypasses said protector means and said protector means is energized through said primary path, and with said switching means blocking said protector means is energized through said alternate path.
Claim 5
Dependent Claim
129 words
Ground fault detector-interrupter means as set forth in claim 2 in which the circuit means also includes primary and alternate current paths between said auxiliary primary and said first and second conductors, respectively; a shunt path connected to said alternate path and said neutral conductor; said shunt path including solid state switching means having a control electrode connected in said primary current path whereby said switching means is conducting when said first conductor is energized and is blocking when said first conductor is deenergized; with said switching means conducting said shunt path being closed whereby current in said alternate path bypasses said auxiliary primary and said protector means is energized through said primary path, and with said switching means blocking said protector means is energized through said alternate path.
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) | 1978-07-14 | 1979-01-13 | 1979-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-14 | 1983-01-13 | 1983-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-14 | 1987-01-13 | 1987-07-15 | $7700.00 | Window Closed / Lapsed |