Patent US3696367A successfully refreshed from Google Patents.
US3696367A
Expired / Lapsed
US
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Ground fault detection circuit
Assignee: Bechtel International Corp
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Filing: 1971-04-21
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Granted: 1972-10-03
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Expires: 1991-04-21
Abstract
Abstract A ground fault detection circuit for use with dual voltage battery systems, comprising first and second ground connected circuits which are alternatively energized depending on the location of a ground fault in any one of three lines connected to the system, and including means for visually observing the extent of such ground faults.
Inventors
- 👤 Sayed-Ibrahim S Inamdar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:20
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/16; G01R27/18
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
233 words
A ground fault detection circuit for a dual voltage battery system having first, second and third lines, one line connected to a common bus and the other two lines connected to the positive and negative sides of said battery system, said circuit comprising: a first ground connected circuit including a set of normally closed contacts; a second ground connected circuit including a set of normally open contacts; means responsive to a momentary current flow through said first circuit for opening said normally closed contacts, interrupting the current flow therethrough, and closing the normally open contacts of said second circuit, allowing current to flow therethrough; means interconnecting said first and second lines and connecting both lines to ground through said first circuit and its normally closed contacts; means interconnecting said second and third lines and connecting both lines to ground through said second circuit and its normally open contacts; and a plurality of means for indicating voltage drops between ground and said first, second and third lines, respectively, one means indicating a voltage drop through the normally closed contacts of said first circuit between ground and said first line, a second means indicating a voltage drop through the normally open contacts of said second circuit between ground and said second line, and a third means indicating a voltage drop through the normally open contacts of said second circuit between ground and said third line.
Claim 2
Dependent Claim
233 words
A ground fault detection circuit for a dual voltage battery system having first, second and third lines, one line connected to a common bus and the other two lines connected to the positive and negative sides of said battery system, said circuit comprising: a first ground connected circuit including a set of normally closed contacts; a second ground connected circuit including a set of normally open contacts; means responsive to a momentary current flow through said first circuit for opening said normally closed contacts, interrupting the current flow therethrough, and closing the normally open contacts of said second circuit, allowing current to flow therethrough; means interconnecting said first and second lines and connecting both lines to ground through said first circuit and its normally closed contacts; means interconnecting said second and third lines and connecting both lines to ground through said second circuit and its normally open contacts; and a plurality of means for indicating voltage drops between ground and said first, second and third lines, respectively, one means indicating a voltage drop through the normally closed contacts of said first circuit between ground and said first line, a second means indicating a voltage drop through the normally open contacts of said second circuit between ground and said second line, and a third means indicating a voltage drop through the normally open contacts of said second circuit between ground and said third line.
Claim 3
Dependent Claim
49 words
The ground fault detection circuit of claim 1 and further comprising an alarm circuit including a set of normally open contacts, a holding cIrcuit including a relay which when energized closes said normally open contacts, and means for deenergizing said holding circuit when current flows through said first circuit.
Claim 4
Dependent Claim
85 words
The ground fault detection circuit of claim 1, said means for indicating voltage drops comprising a first voltmeter connected across a first resistance between said first line and the normally closed contacts of said first ground connected circuit, a second voltmeter connected across a second resistance between said second line and the normally open contacts of said second ground connected circuit, and a third voltmeter connected across a third resistance between said third line and the normally open contacts of said second ground connected circuit.
Claim 5
Dependent Claim
61 words
The ground fault detection circuit of claim 1, said first and second lines being connected to ground through resistances of substantially equal values and through said normally closed contacts of said first ground connected circuit; said second and third lines being connected to ground through resistances of substantially equal value and said normally open contacts of said second ground connected circuit.
Claim 6
Dependent Claim
82 words
The ground fault detection circuit of claim 1, and further including an alarm circuit comprising an alarm relay having a coil connected in series with its normally open contacts and a set of normally closed contacts, means including normally open contacts responsive to a flow of current in said first ground connected circuit for shorting out the coil of said alarm relay, whereby either a positive or negative flow of current causes said alarm relay to be deenergized and signals an alarm.
Claim 7
Dependent Claim
236 words
A ground fault detection circuit for a dual voltage battery system having first, second and third lines, one line connected to a common bus and the other two lines connected to the positive and negative sides of said battery system, said circuit comprising: a milliameter relay having a coil and a set of normally open contacts which are closed by a current flow through the coil; a lock-out relay having a coil, a normally closed set of contacts and a normally open set of contacts; means interconnecting said first and second lines and connecting both lines to ground through the coil of said milliameter relay and the normally closed contacts of said lock-out relay; means for momentarily energizing said lock-out relay through the contacts of said milliameter relay; means interconnecting said second and third lines and connecting both lines to ground through the normally open contacts of said lock-out relay; and a plurality of means for indicating voltage drops between ground and said first, second and third lines, respectively, one means indicating a voltage drop through the normally closed contacts of said lock-out relay between ground and said first line, and a second means indicating a voltage drop through the normally open contacts of said lock-out relay between ground and said second line, and a third means indicating a voltage drop through the normally open contacts of said lock-out relay between ground and said third line.
Claim 8
Dependent Claim
236 words
A ground fault detection circuit for a dual voltage battery system having first, second and third lines, one line connected to a common bus and the other two lines connected to the positive and negative sides of said battery system, said circuit comprising: a milliameter relay having a coil and a set of normally open contacts which are closed by a current flow through the coil; a lock-out relay having a coil, a normally closed set of contacts and a normally open set of contacts; means interconnecting said first and second lines and connecting both lines to ground through the coil of said milliameter relay and the normally closed contacts of said lock-out relay; means for momentarily energizing said lock-out relay through the contacts of said milliameter relay; means interconnecting said second and third lines and connecting both lines to ground through the normally open contacts of said lock-out relay; and a plurality of means for indicating voltage drops between ground and said first, second and third lines, respectively, one means indicating a voltage drop through the normally closed contacts of said lock-out relay between ground and said first line, and a second means indicating a voltage drop through the normally open contacts of said lock-out relay between ground and said second line, and a third means indicating a voltage drop through the normally open contacts of said lock-out relay between ground and said third line.
Claim 9
Dependent Claim
52 words
The ground fault detection circuit of claim 6 and further comprising an alarm circuit including a set of normally open contacts, a holding circuit including a relay which when energized closes said normally open contacts, and means for deenergizing said holding circuit when current flows through the coil of said milliameter relay.
Claim 10
Dependent Claim
73 words
The ground fault detection circuit of claim 6, said means for indicating voltage drops comprising a first voltmeter connected across a first resistance and the coil of said milliameter, a second voltmeter connected across a second resistance and between said second line and said normally open contacts of said lock-out relay, and a third voltmeter connected across a third resistance between the third line and the normally open contacts of said lock-out relay.
Claim 11
Dependent Claim
64 words
The ground fault detection circuit of claim 6, said first and second lines being connected to ground througH resistances of substantially equal values, through the coil of said milliameter relay and through said normally closed contacts of said lock-out relay; said second and third lines being connected to ground through resistances of substantially equal value and said normally open contacts of said lock-out relay.
Claim 12
Dependent Claim
85 words
The ground fault detection circuit of claim 6, and further including an alarm circuit comprising an alarm relay having a coil connected in series with its normally open contacts and a set of normally closed contacts of said lock-out relay, means including normally open contacts operated by said milliameter relay for shorting out the coil of said alarm relay, whereby either a positive or negative flow of current through the coil of said milliameter causes said alarm relay to be deenergized and signals an alarm.
References Cited (Backward Citations)
US2585734A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-03 | 1976-04-03 | 1976-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-03 | 1980-04-03 | 1980-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-03 | 1984-04-03 | 1984-10-03 | $7700.00 | Window Closed / Lapsed |