US3659152A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ground detector and guard circuit
Assignee: Individual
•
Filing: 1970-12-28
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Granted: 1972-04-25
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Expires: 1990-12-28
Abstract
Abstract A ground detection and guard circuit for preventing operation of an appliance or instrument unless the associated supply source has a grounded conductor. The circuit includes a ground wire and a pair of line conductors, with a control relay having one terminal connected to the ground wire and respective neon lamps connected between the line conductors and its other terminal. If one of the line conductors is properly grounded, one of the neon lamps is shorted, allowing the other neon lamp to ignite and energize the control relay.
Inventors
- 👤 Philip A De Langis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:01
CPC Classifications
H; H02; H02H; H02H11/00; H02H11/001
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
148 words
A ground detector and guard circuit devicE comprising plug means engageable in a three-terminal current supply socket of the type having a female ground terminal intended to be internally connected to one of the socket current supply conductors, said plug means having a pair of line prongs and a ground prong, a pair of load conductors and a load ground conductor, relay means having normally open contacts, circuit means including said contacts connecting said line prongs to said load conductors, and respective gas-discharge lamps connected between said line prongs and said load ground conductor through said relay means, whereby one of said lamps will ignite when said plug means is engaged in a supply socket having its female ground terminal internally connected to one of its current supply terminals, providing an indication of a proper ground and causing said relay means to become energized and close said contacts.
Claim 2
Dependent Claim
148 words
A ground detector and guard circuit devicE comprising plug means engageable in a three-terminal current supply socket of the type having a female ground terminal intended to be internally connected to one of the socket current supply conductors, said plug means having a pair of line prongs and a ground prong, a pair of load conductors and a load ground conductor, relay means having normally open contacts, circuit means including said contacts connecting said line prongs to said load conductors, and respective gas-discharge lamps connected between said line prongs and said load ground conductor through said relay means, whereby one of said lamps will ignite when said plug means is engaged in a supply socket having its female ground terminal internally connected to one of its current supply terminals, providing an indication of a proper ground and causing said relay means to become energized and close said contacts.
Claim 3
Dependent Claim
34 words
The ground detector and guard circuit device of claim 1, and an outlet receptacle having load terminals connected respectively to said load conductors and having a ground terminal connected to said load ground conductor.
Claim 4
Dependent Claim
34 words
The ground detector and guard circuit device of claim 1, and wherein said relay means comprises a relay having its winding connected between said ground prong and a common junction of said gas-discharge lamps.
Claim 5
Dependent Claim
43 words
The ground detector and guard circuit device of claim 3, and wherein said relay has two sets of normally open contacts, said circuit means comprising respective connections between said line prongs and load conductors each including a set of said normally open contacts.
Claim 6
Dependent Claim
18 words
The ground detector and guard circuit device of claim 4, and wherein said gas-discharge lamps comprise neon lamps.
Claim 7
Dependent Claim
32 words
The ground detector and guard circuit device of claim 2, and wherein said outlet receptacle is of a type adapted to receive a plug of the same type as said plug means.
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) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |