Patent US4887041A successfully refreshed from Google Patents.
US4887041A
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Method and instrumentation for the detection, location and characterization of partial discharges and faults in electric power cables
Assignee: University of Connecticut
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Filing: 1988-07-07
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Granted: 1989-12-12
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Expires: 2008-07-07
Abstract
Abstract A method and apparatus of detecting the locations of incipient faults in an insulated power line which comprises the method steps of opening one end of the power line, if it is not suitably terminated to reflect high frequency pulses, applying an excitation voltage to the other end of the power line at an excitation point, detecting a first high frequency pulse produced by a discharge in the power line and transmitted on the power line to the excitation point, detecting a first reflection of the pulse from the open end of the power line to the point of excitation, detecting the travel time of a reflection of the first pulse from the excitation point to the open end of the power line and return to the excitation point, and dividing the time between the detection of the first pulse and the first reflected pulse by the detected travel time. The invention also provides a method and means for only detecting discharge pulses which occur in a predetermined range of magnitude of the excitation voltage and discharge pulses which reside within predetermined ranges of magnitudes. The discharge sites may be detected using either reflected voltage or current pulses.
Inventors
- 👤 Matthew S. Mashikian
- 👤 Robert B. Northop
- 👤 Rajeev Bansal
- 👤 Chrysostomos L. Nikias
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:15
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/08; G01R31/11
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
119 words
A method of detecting the locations of incipient faults in an insulated power line comprising the steps of: applying an excitation voltage to one end of said line at an excitation point, detecting a first high frequency pulse produced by a discharge in said line and transmitted on said line to the excitation point, detecting a first reflection of said pulse from the other end of said line, to the point of excitation, detecting the travel time of a reflection of said first pulse from said excitation point to said other end and return to said excitation point, and dividing the time between the detection of said first pulse and said first reflected pulse by said detected travel time.
Claim 2
Independent Claim
119 words
A method of detecting the locations of incipient faults in an insulated power line comprising the steps of: applying an excitation voltage to one end of said line at an excitation point, detecting a first high frequency pulse produced by a discharge in said line and transmitted on said line to the excitation point, detecting a first reflection of said pulse from the other end of said line, to the point of excitation, detecting the travel time of a reflection of said first pulse from said excitation point to said other end and return to said excitation point, and dividing the time between the detection of said first pulse and said first reflected pulse by said detected travel time.
Claim 3
Dependent Claim
24 words
The method of claim 1 further including the step of detecting said pulses only during a predetermined range of magnitude of the excitation voltage.
Claim 4
Dependent Claim
25 words
The method of claim 2 further including the step of detecting said pulses only above a predetermined lower amplitude and below a predetermined upper amplitude.
Claim 5
Dependent Claim
36 words
The method of claim 1 further including the step of recording the wave form received at said excitation point a multiplicity of times and averaging said recordings to reduce the noise content of said wave form.
Claim 6
Dependent Claim
19 words
The method of claim 1 further including the step of removing noise from signals received at said excitation point.
Claim 7
Dependent Claim
25 words
The method of claim 1 further including the step of detecting said pulses only above a predetermined lower amplitude and below a predetermined upper amplitude.
Claim 8
Dependent Claim
26 words
The method of claim 1 further including the step of detecting at said excitation point only signal having a frequency of fifty kHz to ten mHz.
Claim 9
Dependent Claim
19 words
The method of claim 2 including the further step of counting the number of detected pulses per unit time.
Claim 10
Dependent Claim
19 words
The method of claim 6 including the further step of counting the number of detected pulses per unit time.
Claim 11
Dependent Claim
72 words
The method of claim 1 where said cable has an outer conductor and is buried in a trench, and comprising the further steps of applying a pulse to said outer conductor, detecting said pulse and reflections thereof at said excitation point in the same manner as described for the discharge pulse, and determining the cable distance from the excitation point to the point of application of the pulse to the outer conductor.
Claim 12
Dependent Claim
28 words
The method of claim 10 further including the step of calibrating the cable length as a function of the trench length, and physically locating the pulse discharge site.
Claim 13
Independent Claim
119 words
A method of detecting incipient faults in an insulated power line comprising the steps of: opening one end of said line, applying an excitation voltage to the other end of said line, providing an excitation voltage discriminator which is responsive to predetermined ranges of amplitudes of the excitation voltage, applying said excitation voltage or a representation thereof to said discriminator, receiving high frequency pulses produced by a discharge in said line due to said excitation voltage, applying the high received frequency pulses to said discriminator, and detecting by said discriminator, only those high frequency pulses produced by a discharge in said line due to said excitation voltage which are in a predetermined range of amplitude of said excitation voltage.
Claim 14
Independent Claim
119 words
A method of detecting incipient faults in an insulated power line comprising the steps of: opening one end of said line, applying an excitation voltage to the other end of said line, providing an excitation voltage discriminator which is responsive to predetermined ranges of amplitudes of the excitation voltage, applying said excitation voltage or a representation thereof to said discriminator, receiving high frequency pulses produced by a discharge in said line due to said excitation voltage, applying the high received frequency pulses to said discriminator, and detecting by said discriminator, only those high frequency pulses produced by a discharge in said line due to said excitation voltage which are in a predetermined range of amplitude of said excitation voltage.
Claim 15
Dependent Claim
25 words
The method of claim 12 further including the step of detecting said pulses only above a predetermined lower amplitude and below a predetermined upper amplitude.
Claim 16
Dependent Claim
19 words
The method of claim 12 further including the step of removing noise from signals received at said excitation point.
Claim 17
Dependent Claim
18 words
The method of claim 12 further including the step of detecting said pulses only above a predetermined amplitude.
Claim 18
Dependent Claim
26 words
The method of claim 12 further including the step of detecting at said excitation point only signal having a frequency of fifty kHz to ten mHz.
Claim 19
Dependent Claim
19 words
The method of claim 15 including the further step of counting the number of detected pulses per unit time.
Claim 20
Dependent Claim
101 words
Apparatus for detecting incipient faults in an insulated power line comprising: means for applying an excitation voltage to one end of said line, means for receiving at said one end high frequency signals produced by partial discharges at incipient fault sites in said cable and reflections thereof at both ends of said cable, an excitation voltage discriminator, means for applying received high frequency signals to said discriminator, and means for applying the excitation voltage or a sample thereof to said discriminator, said discriminator being effective to detect said high frequency signals only within predetermined ranges of magnitudes of said excitation voltage.
Claim 21
Dependent Claim
101 words
Apparatus for detecting incipient faults in an insulated power line comprising: means for applying an excitation voltage to one end of said line, means for receiving at said one end high frequency signals produced by partial discharges at incipient fault sites in said cable and reflections thereof at both ends of said cable, an excitation voltage discriminator, means for applying received high frequency signals to said discriminator, and means for applying the excitation voltage or a sample thereof to said discriminator, said discriminator being effective to detect said high frequency signals only within predetermined ranges of magnitudes of said excitation voltage.
Claim 22
Dependent Claim
26 words
The apparatus of claim 18 further including means responsive to said voltage discriminator for further detecting signals from pulse discharge site only above a predetermined amplitude.
Claim 23
Independent Claim
142 words
A method of detecting the locations of incipient faults in an insulated power line comprising the steps of: applying an excitation voltage to one end of said line at an excitation point; detecting a first high frequency pulse produced by a discharge in said line and transmitted on said line to the excitation point; detecting a first reflection of said pulse from the other end of said line, to the point of excitation; detecting the travel time of a reflection of said first pulse from said excitation point to said other end and return to said excitation point; dividing the time between the detection of said first pulse and said first reflected pulse by said detected travel time, determining the transfer function of the power line; and utilizing said transfer function to determine the location of the partial discharge in the line.
Claim 24
Independent Claim
142 words
A method of detecting the locations of incipient faults in an insulated power line comprising the steps of: applying an excitation voltage to one end of said line at an excitation point; detecting a first high frequency pulse produced by a discharge in said line and transmitted on said line to the excitation point; detecting a first reflection of said pulse from the other end of said line, to the point of excitation; detecting the travel time of a reflection of said first pulse from said excitation point to said other end and return to said excitation point; dividing the time between the detection of said first pulse and said first reflected pulse by said detected travel time, determining the transfer function of the power line; and utilizing said transfer function to determine the location of the partial discharge in the line.
Claim 25
Dependent Claim
43 words
The method of claim 20 including the steps of recording the partial discharge wave form, digitizing the recorded wave form, and filtering the digitized wave form prior to utilizing said transfer function to determine the location of the partial discharge in the line.
Claim 26
Dependent Claim
23 words
The method of claim 20 including the step of detecting said pulses only during a predetermined range of magnitude of the excitation voltage.
Claim 27
Dependent Claim
24 words
The method of claim 22 including the step of detecting said pulses only above a predetermined lower amplitude and below a predetermined upper amplitude.
Claim 28
Dependent Claim
18 words
The method of claim 20 including the step of removing noise from signals received at said excitation point.
Claim 29
Dependent Claim
24 words
The method of claim 20 including the step of detecting said pulses only above a predetermined lower amplitude and below a predetermined upper amplitude.
Claim 30
Dependent Claim
25 words
The method of claim 20 including the step of detecting at said excitation point only signals having a frequency of fifty kHz to ten mHz.
Claim 31
Dependent Claim
18 words
The method of claim 22 including the step of counting the number of detected pulses per unit time.
Claim 32
Dependent Claim
18 words
The method of claim 25 including the step of counting the number of detected pulses per unit time.
Claim 33
Dependent Claim
72 words
The method of claim 20 where said cable has an outer conductor and is buried in a trench, and comprising the further steps of applying a pulse to said outer conductor, detecting said pulse and reflections thereof at said excitation point in the same manner as described for the discharge pulse, and determining the cable distance from the excitation point to the point of application of the pulse to the outer conductor.
Claim 34
Dependent Claim
28 words
The method of claim 29 further including the step of calibrating the cable length as a function of the trench length, and physically locating the pulse discharge site.
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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) | 1992-12-11 | 1993-06-12 | 1993-12-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-11 | 1997-06-12 | 1997-12-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-11 | 2001-06-12 | 2001-12-12 | $7700.00 | Window Closed / Lapsed |