US3678338A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protective automatically disconnectable grouping means for an ungrounded a.c. electrical distribution system
Assignee: Individual
•
Filing: 1971-02-25
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Granted: 1972-07-18
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Expires: 1991-02-25
Abstract
Abstract An ungrounded a.c. electrical distribution system is provided with a protective grounding device in circuit with means for automatically disconnecting the grounding device in the event that a fault to ground occurs on any line of the system. The grounding device can be a transformer having a neutral grounded point. The automatic disconnection means may be circuit breakers or current limiting fuses and may further include a relay assembly having automatically opening contacts. The relay assembly can be thermally operable. The transformer can be a zigzag transformer. External signal devices can be connected to the relay assembly.
Inventors
- 👤 Robert W Beachley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 09:14
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/16; H02H3/162; H02H3/165
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
187 words
Protective means for a normally ungrounded electrical distribution system having a plurality of ungrounded conductors connected to a load, comprising automatically openable current conducting means responsive to any current above a predetermined magnitude connected to said conductors respectively and arranged to open when current in any one of said current conductive means rises above said magnitude; and a grounding device connectable and when in use connected between said conductive means and ground to provide a neutral ground for the ungrounded conductors, whereby said grounding device is automatically cut off from said conductors when a fault to ground of sufficient magnitude and duration occurs between any one of said conductors and ground, said automatically opening current conductive means comprising for each of said ungrounded conductors switch means and fuse in series circuits with said grounding device and in parallel with said load to said conductors, when said conductors are connected, and the automatically opening current conductive means comprising a relay assembly including automatically opening current overload switch contacts in series with said grounding device and in parallel with said load to said conductors, when said conductors are connected.
Claim 2
Dependent Claim
187 words
Protective means for a normally ungrounded electrical distribution system having a plurality of ungrounded conductors connected to a load, comprising automatically openable current conducting means responsive to any current above a predetermined magnitude connected to said conductors respectively and arranged to open when current in any one of said current conductive means rises above said magnitude; and a grounding device connectable and when in use connected between said conductive means and ground to provide a neutral ground for the ungrounded conductors, whereby said grounding device is automatically cut off from said conductors when a fault to ground of sufficient magnitude and duration occurs between any one of said conductors and ground, said automatically opening current conductive means comprising for each of said ungrounded conductors switch means and fuse in series circuits with said grounding device and in parallel with said load to said conductors, when said conductors are connected, and the automatically opening current conductive means comprising a relay assembly including automatically opening current overload switch contacts in series with said grounding device and in parallel with said load to said conductors, when said conductors are connected.
Claim 3
Dependent Claim
16 words
Protective means as defined in claim 1, including said ungrounded conductors in an operatively connected state.
Claim 4
Dependent Claim
31 words
Protective means as defined in claim 1, wherein the automatically opening current conductive means further comprises current limiting fuses connected in said series circuits with said switch contacts and said ground.
Claim 5
Dependent Claim
63 words
Protective means as defined in claim 1, wherein said relay assembly has thermally responsive elements arranged to open said contacts in response to excessive current passing therethrough, wherein the automatically opening current conductive means further comprises current limiting fuses connected in series circuits with said switch contacts and said ground, and wherein said grounding device is a transformer having a neutral grounding point.
Claim 6
Dependent Claim
37 words
Protective means as defined in claim 4, wherein said relay assembly further includes means for connecting an external signal device thereto for indicating when said fault to ground occurs, and wherein said transformer is a zigzag transformer.
Claim 7
Dependent Claim
27 words
Protective means as defined in claim 1, wherein said relay assembly has thermally responsive elements arranged to open said contacts in response to excessive current passing therethrough.
Claim 8
Dependent Claim
19 words
Protective means as defined in claim 1, wherein said grounding device is a transformer having a neutral grounding point.
Claim 9
Dependent Claim
14 words
Protective means as defined in claim 7, wherein said transformer is a zig-zag transformer.
Claim 10
Dependent Claim
29 words
Protective means as defined in claim 1, wherein said relay assembly further includes means for connecting an external signal device thereto for indicating when said fault to ground occurs.
Claim 11
Dependent Claim
19 words
Protective means as defined in claim 9, wherein said grounding device is a transformer having a neutral grounding point.
References Cited (Backward Citations)
US1731971A
Cited
US2523778A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-18 | 1976-01-17 | 1976-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-18 | 1980-01-17 | 1980-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-18 | 1984-01-17 | 1984-07-18 | $7700.00 | Window Closed / Lapsed |