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Patent US3789293A successfully refreshed from Google Patents.
US3789293A
Expired / Lapsed
US
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Electrical current monitor which separately indicates individual and sustained current pulses
Assignee: ABB Inc USA
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Filing: 1972-06-15
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Granted: 1974-01-29
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Expires: 1992-06-15
Abstract
Abstract Transformer fault current monitor which provides recorded indications of the number of times any fault currents have occurred and also of the number of times fault currents which have a duration of more than a predetermined length of time have occurred. In one embodiment, a magnetic reed switch is positioned in the magnetic field produced by the monitored current. When the reed switch is closed by a high magnetic field, a voltage is applied to a peak detector circuit. The voltage is peak detected and applied to first and second counting means. The first counting means is activated when the monitored current exceeds a predetermined level. The second counting means is activated when the monitored current exceeds a predetermined level for a predetermined length of time. In another embodiment, magnetic diodes are positioned in the magnetic field produced by the monitored current. The magentic diodes are connected to a differential amplifier which provides an output voltage when a sufficient magnetic field surrounds the diodes. The differential amplifier is connected, through suitable circuitry, to first and second counting means.
Inventors
- 👤 J Freeze
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:58
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/30; G01R19/04; G01R19/25; G01R19/255
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
27 words
The current monitor of claim 1 wherein the first switching means comprises a magnetic reed switch which is positioned in the magnetic field of the monitored current.
Claim 2
Dependent Claim
34 words
The current monitor of claim 1 wherein the peak detecting means comprises energy storing means, said energy storing means maintaining a voltage thereon having a magnitude which is substantially equal to the first voltage.
Claim 3
Dependent Claim
63 words
The current monitor of claim 1 wherein the first counting means comprises an electromechanical indicating means which provides an additional indication each time the electromechanical indicating means is energized, said electromechanical indicating means being energized by second switching means, the second voltage being applied to said second switching means, and said second switching means conducting when the second voltage exceeds the predetermined magnitude.
Claim 4
Dependent Claim
69 words
The current monitor of claim 1 wherein the second counting means comprises an electromechanical indicating means which provides an additional indication each time the electromechanical indicating means is energized, said electromechanical indicating means being energized by third switching means, the second voltage being applied to said third switching means, and said third switching means conducting when the second voltage exceeds the predetermined magnitude for the predetermined length of time.
Claim 5
Dependent Claim
72 words
The current monitor of claim 5 wherein the third switching means comprises energy storing means which is electrically connected to the second voltage through an impedance means, said energy storing means developing a third voltage thereon when the second voltage exceeds the predetermined magnitude for the predetermined length of time, said third voltage being applied to a solid state circuit element, said circuit element conducting when the third voltage is applied thereto.
Claim 6
Dependent Claim
238 words
A current monitor comprising a magnetic reed switch positioned in a magnetic field of the monitored current, a voltage source connected to said magnetic reed switch, energy storing means, isolation means connected between said magnetic reed switch and said energy storing means, first and second counting means, said first counting means being connected to said energy storing means and providing an indication of the number of times the monitored current exceeds a predetermined magnitude, a serial combination of a resistor and a capacitor connected to said energy storing means, said second counting means being connected to said serial combination and providing an indication of the number of times the monitored current exceeds the predetermined magnitude for a predetermined length of time. 8. A current monitor comprising magnetic diodes which are responsive to the magnetic field of a monitored current, a differential amplifier connected to said magnetic diodes and providing a first output voltage, peak detecting means which provides a second output voltage which is proportional to the peak of the first output voltage, first counting means connected to said peak detecting means, said first counting means providing an indication of the number of times the second output voltage exceeds a predetermined magnitude, and second counting means connected to said peak detecting means, said second counting means providing an indication of the number of times the second output voltage exceeds the predetermined magnitude for a predetermined length of time.
Claim 7
Dependent Claim
81 words
The current monitor of claim 8 wherein the magnetic diodes are serially connected to a constant current source, s first of said diodes being positioned in the magnetic field of the monitored current to provide a decrease in its forward conduction resistance with an increase in the magnetic field, and a second of said diodes being positioned in the magnetic field of the monitored current to provide an increase in its forward conduction resistance with an increase in the magnetic field.
Claim 8
Dependent Claim
40 words
The current monitor of claim 8 wherein the peak detecting means comprises energy storing means, said energy storing means maintaining a second output voltage thereon having a magnitude which is substantially equal to the peak of the first output voltage.
Claim 9
Dependent Claim
65 words
The current monitor of claim 8 wherein the first coupling means comprises an electromechanical indicating means which provides an additional indication each time the electromechanical indicating means is energized, said electromechanical indicating means being energized by first switching means, the second output voltage being applied to said first switching means, and said first switching means conducting when the second output voltage exceeds the predetermined magnitude.
Claim 10
Dependent Claim
71 words
The current monitor of claim 8 wherein the second counting means comprises an electromechanical indicating means which provides an additional indication each time the electromechanical indicating means is energized, said electromechanical indicating means being energized by second switching means, the second output voltage being applied to said second switching means, and said second switching means conducting when the second output voltage exceeds the predetermined magnitude for the predetermined length of time.
Claim 11
Dependent Claim
74 words
The current monitor of claim 12 wherein the second switching means comprises energy storing means which is electrically connected to the second output voltage through an impedance means, said energy storing means developing a third voltage thereon when the second output voltage exceeds the predetermined magnitude for the predetermined length and time, said third voltage being applied to a solid state circuit element, said circuit element conducting when the third voltage is applied thereto.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |