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Patent US3823342A successfully refreshed from Google Patents.
US3823342A
Expired / Lapsed
US
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Voltage protection circuitry for direct current powered machinery
Assignee: Consolidation Coal Co
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Filing: 1973-06-25
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Granted: 1974-07-09
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Expires: 1993-06-25
Abstract
Abstract A diode and a current limiting resistor are serially connected between a grounded electrical conductor and the frame portion of an electrically operable machine supplied with direct current power from a remote power source through trailing conductors connected to the machine load. The diode is operable to prevent the frame from being raised to the full-line voltage of the power source in the event the polarity of the conductors is reversed. The current limiting resistor limits the flow of current, caused by transient voltages appearing on the frame, to an intrinsically safe level. A capacitor and a plurality of resistors arranged in parallel circuit relation with the current limiting resistor monitor the existence of a fault voltage appearing thereacross. When the capacitor receives a charge of a predetermined magnitude, a diac serially connected to the capacitor conducts current therethrough to the gate terminal of a first silicon controlled rectifier. The first silicon controlled rectifier switched to a conductive state provides a direct path for the flow of current from the frame to the grounded conductor. A second silicon controlled rectifier, switched to a conductive state upon actuation of the first silicon controlled rectifier, deenergizes a relay to thereby terminate operation of the machine and signal the condition of fault voltage applied to the frame.
Inventors
- 👤 J Burr
- 👤 G Powell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:01
CPC Classifications
H; H02; H02H; H02H11/00; H02H11/002; H02H3/00; H02H3/14
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
158 words
In a voltage protection circuit for direct current powered machinery having conducting means for supplying direct current power to an electrically operable load with one polarity connected to ground, means for limiting the flow of current through the machine frame to a predetermined magnitude, voltage protection means for preventing said frame from being charged to the full magnitude of the direct current power supplied to said electrically operable load, and grounding means for directing the flow of fault voltage current applied to said frame to said conducting means connected to ground, the improvement comprising, sensing means for monitoring the actuation of said grounding means to ground said frame, said sensing means connected in a series circuit with said voltage protection means and said grounding means, and signal means for indicating the condition of fault voltage current applied to said frame, said signal means coupled to said sensing means and connected in a parallel circuit with said conducting means.
Claim 2
Dependent Claim
158 words
In a voltage protection circuit for direct current powered machinery having conducting means for supplying direct current power to an electrically operable load with one polarity connected to ground, means for limiting the flow of current through the machine frame to a predetermined magnitude, voltage protection means for preventing said frame from being charged to the full magnitude of the direct current power supplied to said electrically operable load, and grounding means for directing the flow of fault voltage current applied to said frame to said conducting means connected to ground, the improvement comprising, sensing means for monitoring the actuation of said grounding means to ground said frame, said sensing means connected in a series circuit with said voltage protection means and said grounding means, and signal means for indicating the condition of fault voltage current applied to said frame, said signal means coupled to said sensing means and connected in a parallel circuit with said conducting means.
Claim 3
Dependent Claim
31 words
In a voltage protection circuit for direct current powered machinery, the improvement as set forth in claim 1 which includes, said signal means actuated by current passing through said sensing means.
Claim 4
Dependent Claim
43 words
In a voltage protection circuit for direct current powered machinery, the improvement as set forth in claim 1 which includes, said signal means actuated by current passing through said sensing means to thereby terminate the supply of direct current power to said load.
Claim 5
Dependent Claim
57 words
In a voltage protection circuit for direct current powered machinery, the improvement as set forth in claim 1 in which said sensing means includes, a pulse transformer having a primary and a secondary winding, said primary winding serially connected to said current limiting means and said grounding means, said secondary winding serially connected to said signal means.
Claim 6
Dependent Claim
60 words
In a voltage protection circuit for direct current powered machinery, the improvement as set forth in claim 4 wherein, said primary winding energizes said secondary winding to conduct current when current flows through said primary winding, said secondary winding, energized by said primary winding, actuates said signal means to indicate the condition of fault voltage current applied to said frame.
Claim 7
Dependent Claim
45 words
In a voltage protection circuit for direct current powered machinery, the improvement as set forth in claim 1 in which said signal means includes, means for terminating the supply of direct current power to said load when fault voltage current is applied to said frame.
Claim 8
Dependent Claim
88 words
In a Voltage protection circuit for direct current powered machinery, the improvement as set forth in claim 1 in which said means for terminating the supply of direct current power to said load includes, a normally energized relay, a silicon controlled rectifier having a gate terminal connected to said sensing means and an anode and a cathode connected across said normally energized relay, and a normally energized contactor for controlling the flow of direct current power to said load, said contactor connected between said relay and said load.
Claim 9
Dependent Claim
50 words
In a voltage protection circuit for direct current powered machinery, the improvement as set forth in claim 7 which includes, said silicon controlled rectifier operable to conduct current from said anode to said cathode when voltage is applied to said gate terminal to thereby deenergize said relay and said contactor.
Claim 10
Dependent Claim
58 words
In a voltage protection circuit for direct current powered machinery, the improvement as set forth in claim 7 in which said contactor includes, a contact connected to said conducting means and in series circuit with said load, said contact opened by deenergizing said contactor to interrupt the direct current power supplied to said load by said conducting means.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-08 | 1978-01-07 | 1978-07-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-08 | 1982-01-07 | 1982-07-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-08 | 1986-01-07 | 1986-07-09 | $7700.00 | Window Closed / Lapsed |