US3648111A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for sensing overcurrent and ground leakage current
Assignee: Individual
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Filing: 1970-12-17
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Granted: 1972-03-07
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Expires: 1990-12-17
Abstract
Abstract Apparatus for connection in series with power equipment and a grounded AC power source which enables sensing of ground lead leakage current and excess power consumption to open the power application circuit and avoid damaging conditions and effects to the power equipment and/or operator. The apparatus consists of a momentary pushbutton switch and holding relay connected in series with the AC powerline to enable application of electric power to the power equipment. Both an excess power-sensing circuit and a ground current leakage-sensing circuit provide input to a normally nonconductive reactance stage which, in the event of sense input, is biased to the conductive state thereby to effect deenergization of the holding relay to release the pushbutton switch contacts.
Inventors
- 👤 Guy E Howe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 04:05
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/16; H02H3/162; H02H3/08; H02H3/10; H02H3/105
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
199 words
Apparatus for automatic control of energization of electrical power-consuming equipment, comprising: alternating current conducting means connected between an alternating current power source including a system ground and an alternating current input to said electrical power-consuming equipment, said alternating current input consisting of first and second power leads and a ground lead; first sensing means connected in series with said ground lead to provide a first sense output; second sensing means connected in series with one of said first and second power leads to provide a second sense output; transistor means which is normally nonconducting and receiving input from each of said first and second sense outputs, and to be rendered conductive upon input of predetermined voltage and current values; switch means in series with said first and second power means; holding relay means connected in parallel to each of first and second power leads and energized upon closure of said switch means to hold said switch means in the closed position; and second transistor means which is normally conducting to maintain said holding relay means energized and which is connected to be cut off in response to conduction of said first reactance means to deenergize said holding relay means.
Claim 2
Dependent Claim
199 words
Apparatus for automatic control of energization of electrical power-consuming equipment, comprising: alternating current conducting means connected between an alternating current power source including a system ground and an alternating current input to said electrical power-consuming equipment, said alternating current input consisting of first and second power leads and a ground lead; first sensing means connected in series with said ground lead to provide a first sense output; second sensing means connected in series with one of said first and second power leads to provide a second sense output; transistor means which is normally nonconducting and receiving input from each of said first and second sense outputs, and to be rendered conductive upon input of predetermined voltage and current values; switch means in series with said first and second power means; holding relay means connected in parallel to each of first and second power leads and energized upon closure of said switch means to hold said switch means in the closed position; and second transistor means which is normally conducting to maintain said holding relay means energized and which is connected to be cut off in response to conduction of said first reactance means to deenergize said holding relay means.
Claim 3
Dependent Claim
50 words
Apparatus as set forth in claim 1 wherein said first sensing means comprises: rectifier means connected between said system ground and said ground lead, said rectifier means having a predetermined voltage drop thereacross, said first sense output being taken from the junction of said rectifier means and said ground lead.
Claim 4
Dependent Claim
34 words
Apparatus as set forth in claim 2 wherein said rectifier means comprises: first and second silicon diode rectifiers connected in series and like polarity to exhibit a total voltage drop of 1.2 volts thereacross.
Claim 5
Dependent Claim
38 words
Apparatus as set forth in claim 3 which is further characterized to include: third and fourth silicon rectifier means connected in series and like but opposite polarity from said first and second rectifier means and in parallel therewith.
Claim 6
Dependent Claim
42 words
Apparatus as set forth in claim 1 wherein said transistor means comprises: NPN transistor means having its base connected to each of said first and second sense outputs and being nonconducting in absence of one or the other of said sense outputs.
Claim 7
Dependent Claim
68 words
Apparatus as set forth in claim 5 which is further characterized to include: PNP transistor means having the base connected to the collector of said NPN transistor means, and being biased to be rendered conductive in response to conductivity of said NPN transistor, said conductive output of said NPN transistor being applied to said second transistor means to cut off conduction therein thereby to deenergize said holding means.
Claim 8
Dependent Claim
62 words
Apparatus as set forth in claim 1 wherein said second sensing means comprises: toroidal transformer means having a primary winding connected in series with one of said first and second power leads, and having a secondary winding providing an AC sense output; and rectifier sensing means receiving said AC sensing output to provide a DC output voltage as said second sense output.
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) | 1975-03-07 | 1975-09-06 | 1976-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-07 | 1979-09-06 | 1980-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-07 | 1983-09-06 | 1984-03-07 | $7700.00 | Window Closed / Lapsed |