US3746929A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ground continuity checking system
Assignee: General Electric Co
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Filing: 1971-09-28
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Granted: 1973-07-17
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Expires: 1991-09-28
Abstract
Abstract A fail-safe ground conductor continuity monitoring circuit including means for inserting a low-level monitoring current into a ground conductor and receiver means for sensing if the level of current in the ground conductor is below a predetermined level and for tripping a circuit breaker if the current is below that level for a predetermined period of time. The receiver also includes means for insuring that the current in the receiver does not reverse as a result of stray ground currents or power currents in the ground conductor.
Inventors
- 👤 W Kotheimer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:05
CPC Classifications
H; H02; H02H; H02H11/00; H02H11/001
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
153 words
In a system for supplying electric power from a fixed source location through a cable including a ground conductor to a remote load device having a conductive frame, said ground conductor being connected to said frame, a source of alternating electric power current supply at said source loaction, a source of pulsating unidirectional signal current including an alternating component having a ripple frequency, a ground monitor circuit including said ground conductor connected normally to conduct said signal current, a bridge rectifier having alternating current input terminals directly conductively connected in said ground monitor circuit and including direct current output terminals, and a normally energized signal current responsive relay connected across said direct current output terminals, the drop-out current of said relay being less than the maximum value of said alternating signal current component and said relay having a drop-out time characteristic at least substantially equal to the cycle time of said ripple frequency.
Claim 2
Dependent Claim
153 words
In a system for supplying electric power from a fixed source location through a cable including a ground conductor to a remote load device having a conductive frame, said ground conductor being connected to said frame, a source of alternating electric power current supply at said source loaction, a source of pulsating unidirectional signal current including an alternating component having a ripple frequency, a ground monitor circuit including said ground conductor connected normally to conduct said signal current, a bridge rectifier having alternating current input terminals directly conductively connected in said ground monitor circuit and including direct current output terminals, and a normally energized signal current responsive relay connected across said direct current output terminals, the drop-out current of said relay being less than the maximum value of said alternating signal current component and said relay having a drop-out time characteristic at least substantially equal to the cycle time of said ripple frequency.
Claim 3
Dependent Claim
28 words
An electric power system according to claim 1 wherein said source of signal current comprises rectifier means having an input circuit connected to said source of power current.
Claim 4
Dependent Claim
27 words
An electric power system according to claim 2 wherein said power current source is multiphase and said ripple frequency is a harmonic of the power current frequency.
Claim 5
Dependent Claim
34 words
An electric power system according to claim 1 wherein the alternating current input terminals of said bridge rectifier are conductively connected directly between said ground conductor and a ground terminal at said source location.
Claim 6
Dependent Claim
27 words
An electric power system according to claim 1 wherein said signal current responsive relay comprises a coil connected in parallel circuit relation with a voltage limiting impedance.
Claim 7
Dependent Claim
34 words
An electric power system according to claim 5 wherein said voltage limiting impedance comprises a diode rectifier connected to conduct in the forward direction between the direct current output terminals of said bridge rectifier.
Claim 8
Dependent Claim
45 words
A ground monitor circuit according to between 1 wherein said ground monitor circuit comprises a loop circuit extending between said source location and said load device including ground conductor and a substantially coextensive pilot wire and said bridge rectifier is located at sAid source location.
Claim 9
Dependent Claim
45 words
A ground monitor circuit according to between 1 wherein said ground monitor circuit comprises a loop circuit extending between said source location and said load device including ground conductor and a substantially coextensive pilot wire and said bridge rectifier is located at sAid source location.
Claim 10
Dependent Claim
21 words
A ground monitor circuit according to claim 7 wherein said signal current source is conductively independent of the main power circuit.
References Cited (Backward Citations)
US2880377A
Cited
US3335324A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-16 | 1977-01-15 | 1977-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-16 | 1981-01-15 | 1981-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-16 | 1985-01-15 | 1985-07-17 | $7700.00 | Window Closed / Lapsed |