Patent US3697809A successfully refreshed from Google Patents.
US3697809A
Expired / Lapsed
US
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Ground wire monitoring system with fail-safe power disconnect
Assignee: Joy Manufacturing Co
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Filing: 1970-11-23
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Granted: 1972-10-10
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Expires: 1990-11-23
Abstract
Abstract A system for monitoring the continuity of a ground wire between a remote machine, such as a mining machine, and a power source supplying polyphase power to the machine via a plurality of conductors wherein a DC signal is provided at the machine in response to the purchase power. The DC signal is applied to the ground wire for transmission to the power source, with the receipt of the DC signal at the power source being indicative of continuity of the ground wire and the absence of the DC signal being indicative of non-continuity, such latter indication being employable to disconnect the power from the remote machine.
Inventors
- 👤 William R Self
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:29
CPC Classifications
H; H02; H02H; H02H11/00; H02H11/001
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
128 words
In apparatus including a power source for supplying a remote machine with polyphase current via a plurality of conductors and wherein a single ground wire is connected between power source ground and said remote machine, a system for monitoring the continuity of said ground wire comprising: conversion means at said remote machine for providing a DC signal in response to said polyphase current supplied at said machine and for applying said DC signal to said ground wire alone for transmission to said power source; and sensing means at said power source responsive to the presence of said DC signal to provide an indication of continuity of said ground wire and responsive to the absence of said DC signal to provide an indication of non-continuity of said ground wire.
Claim 2
Dependent Claim
128 words
In apparatus including a power source for supplying a remote machine with polyphase current via a plurality of conductors and wherein a single ground wire is connected between power source ground and said remote machine, a system for monitoring the continuity of said ground wire comprising: conversion means at said remote machine for providing a DC signal in response to said polyphase current supplied at said machine and for applying said DC signal to said ground wire alone for transmission to said power source; and sensing means at said power source responsive to the presence of said DC signal to provide an indication of continuity of said ground wire and responsive to the absence of said DC signal to provide an indication of non-continuity of said ground wire.
Claim 3
Dependent Claim
28 words
The system of claim 1 wherein said apparatus includes circuit breaker means for disconnecting said polyphase current from said remote machine in response to said indication of non-continuity.
Claim 4
Dependent Claim
23 words
The system of claim 2 wherein: said conversion means includes a rectifying means responsive to said alternating current for providing said DC signal.
Claim 5
Dependent Claim
28 words
The system of claim 3 wherein: said conversion means includes winding means responsive to said alternating current for providing a suitable output for application to said rectifying means.
Claim 6
Dependent Claim
80 words
The system of claim 2 wherein: said sensing means includes monitor impedance means operatively connected between said ground wire and said power source ground and responsive to said DC signal to provide a predetermined input signal, and amplifying means responsive to said predetermined input signal to provide an output as said indication of continuity of said ground wire, said circuit breaker means operative to disconnect said remote machine in response to the absence of said output from said amplifying means.
Claim 7
Dependent Claim
78 words
The system of claim 4 wherein said apparatus includes a polyphase power transformer having a neutral junction thereon, a neutral grounding impedance means connected between said junction and said power source ground to limit ground fault current to within predetermined limits, said winding means of said conversion means comprising a polyphase reference winding, and said rectifying means includes a plurality of rectifying devices connected respectively to each phase of said polyphase reference winding to provide said DC signal.
Claim 8
Dependent Claim
30 words
The system of claim 6 wherein: said polyphase reference winding having tap points on the respective windings thereof for developing said suitable output for application to said rectifying devices respectively.
Claim 9
Dependent Claim
26 words
The system of claim 7 includes: load impedance means for connecting each of said plurality of rectifying devices to said ground wire at said remote machine.
Claim 10
Dependent Claim
80 words
The system of claim 5 wherein said circuit breaker means includes a trip coil which when in a first state will permit said circuit breaker to remain closed and when in a second state will cause said circuit breaker means to trip, said system includes: means responsive to said output of said amplifying means to cause said trip coil to be placed in said first state and in the absence of said output to be placed in said second state.
Claim 11
Dependent Claim
75 words
The combination of claim 9 includes: start switch means for instigating the start-up of said system; and time delay means responsive to said instigation of start-up to cause said trip means to be placed in said first state for a predetermined time and then to revert to said second state after said predetermined time unless said output from said amplifying means is provided in response to said DC signal being received at said power source.
Claim 12
Dependent Claim
21 words
The combination of claim 10 wherein said start switch means and said time delay means are located at said power source.
References Cited (Backward Citations)
US3196316A
Cited
US3579037A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-10 | 1976-04-10 | 1976-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-10 | 1980-04-10 | 1980-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-10 | 1984-04-10 | 1984-10-10 | $7700.00 | Window Closed / Lapsed |