Patent US3707674A successfully refreshed from Google Patents.
US3707674A
Expired / Lapsed
US
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Method and apparatus for measuring corona inception voltage on overhead conductors and the like
Assignee: General Cable Corp
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Filing: 1971-04-05
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Granted: 1972-12-26
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Expires: 1991-04-05
Abstract
Abstract With this invention, corona inception voltage in uninsulated overhead lines is detected by placing a sensitive direct current galvanometer in position to detect the change from negative to positive space charge around the overhead conductor when corona discharge begins. The galvanometer, with low pass filters, is placed in series with the power line, and the low pass filters prevent the relatively heavy capacitive alternating current from flowing through the direct current galvanometer coil.
Inventors
- 👤 George Bahder
- 👤 Felipe G Garcia
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:49
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/12
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
95 words
The method of detection of corona Of an electric circuit comprising locating at least a part of the circuit in a space having a positive space charge, impressing an alternating current voltage on the circuit less than the corona inception voltage, initially detecting the net negative flow in the circuit, upon said circuit providing a corona discharge detecting the change from negative to positive current flow caused by the corona discharge that creates a negative field that replaces the positive space charge, and detecting corona inception by change in current to a net positive flow.
Claim 2
Independent Claim
95 words
The method of detection of corona Of an electric circuit comprising locating at least a part of the circuit in a space having a positive space charge, impressing an alternating current voltage on the circuit less than the corona inception voltage, initially detecting the net negative flow in the circuit, upon said circuit providing a corona discharge detecting the change from negative to positive current flow caused by the corona discharge that creates a negative field that replaces the positive space charge, and detecting corona inception by change in current to a net positive flow.
Claim 3
Dependent Claim
85 words
The method of detecting corona described in claim 1 characterized by the circuit including an overhead cable and the positive space charge around the cable being produced by a continuous bombardment of cosmic rays of the atmospheric gases surrounding the cable to produce positive and negative (electrons) ions in the atmosphere where the alternating electric field of the cable causes drift of the ions with resulting escape of the low mass electrons leaving a net positive space charge at voltages below the corona inception voltage.
Claim 4
Dependent Claim
63 words
The method of detecting corona described in claim 2 characterized by increasing the alternating current voltage on the overhead cable until the inception of corona discharge creates the negative field, detecting the change in the direction of net current flow by connecting a galvanometer in series with the cable and protecting the galvanometer from heavy capacitance alternating current by a low pass filter.
Claim 5
Dependent Claim
46 words
The method of detecting corona described in claim 1 characterized by detecting the net negative current flow and the subsequent net positive current flow on the ground side of a power source that supplies the alternating current voltage to the part of the circuit being tested.
Claim 6
Dependent Claim
48 words
The method of detecting corona described in claim 1 characterized by detecting the net negative current flow and the subsequent net positive current flow at a location between the circuit to be tested and a power source that supplies to the circuit the voltage that produces the corona.
Claim 7
Independent Claim
153 words
An apparatus for determining corona inception of an electric circuit or a part thereof including in combination means for detecting the direction of net current flow when the voltage on the circuit is less than its corona inception voltage and at least a part of the circuit to be tested is surrounded by a positive space charge that causes a negative net current flow in the circuit, a source of alternating current at variable voltage that can be increased to a voltage in excess of the corona inception voltage of the circuit or the part thereof for which the corona inception voltage is to be determined, and a voltage-responsive device that indicates the existing voltage when corona discharge begins and the corona penetrates the space charge layer and changes the space charge layer with resulting changes in the space charge from positive to negative and thereby reverses the direction of net current flow.
Claim 8
Independent Claim
153 words
An apparatus for determining corona inception of an electric circuit or a part thereof including in combination means for detecting the direction of net current flow when the voltage on the circuit is less than its corona inception voltage and at least a part of the circuit to be tested is surrounded by a positive space charge that causes a negative net current flow in the circuit, a source of alternating current at variable voltage that can be increased to a voltage in excess of the corona inception voltage of the circuit or the part thereof for which the corona inception voltage is to be determined, and a voltage-responsive device that indicates the existing voltage when corona discharge begins and the corona penetrates the space charge layer and changes the space charge layer with resulting changes in the space charge from positive to negative and thereby reverses the direction of net current flow.
Claim 9
Dependent Claim
90 words
The apparatus described in claim 6 characterized by the part of the circuit to be tested having an overhead power line with a positive space charge on the atmosphere surrounding the power line produced by the continuous bombardment by cosmic rays of the atmospheric gases surrounding the line to produce positive and negative (electrons) ions in the atmosphere where the alternating electric field of the cable causes drift of the ions with resulting escape of the low mass electrons leaving a net positive space charge layer around the power line.
Claim 10
Dependent Claim
57 words
The apparatus described in claim 7 characterized by poles by which the overhead line is supported, the means of detecting the direction of net current flow being a galvanometer, said galvanometer being supported at a location along the line in a position where the galvanometer can be read from the ground by a telescope or binoculars. WI
Claim 11
Dependent Claim
57 words
The apparatus described in claim 6 characterized by the means for detecting the direction of net current flow being a direct current gaLvanometer having a coil, and a low pass filter connected with the galvanometer and the power line for preventing the relatively heavy capacative alternating current from flowing through the coil of the direct current galvanometer.
Claim 12
Dependent Claim
54 words
The apparatus described in claim 9 characterized by the low pass filter including a plurality of capacitors forming a bank of capacitors that is in series with the power line, the individual capacitors being in parallel with one another and in parallel with the galvanometer, and inductances connecting the parallel capacitors with one another.
Claim 13
Dependent Claim
48 words
The apparatus described in claim 10 characterized by the means for detecting the direction of net current flow when the voltage on the circuit is less than its corona inception voltage being in series with the circuit and between said circuit and a source of alternating current voltage.
Claim 14
Dependent Claim
31 words
The apparatus described in claim 11 characterized by the means for detecting the direction of net current flow being on the ground side of the source of alternating current variable voltage.
References Cited (Backward Citations)
US2802180A
Cited
US2890420A
Cited
US2965755A
Cited
US3263165A
Cited
US3430137A
Cited
US3505597A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-26 | 1976-06-26 | 1976-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-26 | 1980-06-26 | 1980-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-26 | 1984-06-26 | 1984-12-26 | $7700.00 | Window Closed / Lapsed |