Patent US5767684A successfully refreshed from Google Patents.
US5767684A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for measuring partial discharges in cables
Assignee: Kema NV
•
Filing: 1993-11-05
•
Granted: 1998-06-16
•
Expires: 2013-11-05
Abstract
Abstract The invention relates to a method for detecting partial discharges occurring in a cable, wherein the cable has an earth screen with a helical structure, comprising the following steps of: arranging at least one detection coil round the cable for detecting electromagnetic pulses travelling along the cable; applying a potential difference between the core and the earth shield of the cable; and analyzing pulses generated by possible partial discharges in the at least one detection coil in order to determine the location and quality of the partial discharge having caused the pulse, wherein the detection coil is adapted to process signals with a frequency higher than 100 MHz. It has been found that with coils comprising only such a limited number of turns the signal detected by the coil is a much better representation of the form of the electromagnetic pulse travelling along the cable.
Inventors
- 👤 Evert Frederik Steennis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:05
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/08; G01R31/081; G01R31/083; G01R15/00; G01R15/14; G01R15/18; G01R31/12; G01R31/1227; G01R31/1263; G01R31/1272
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
138 words
Method for detecting partial discharges occurring in a cable, wherein the cable has a core and an earth shield with a helical structure, comprising the following steps of: arranging at least one detection coil around the cable so as not to locally destruct the cable and for detecting electromagnetic pulses traveling along the cable; applying a potential difference between the core and the earth shield of the cable; and analyzing pulses generated by possible partial discharges in at least one detection coil in order to determine the location and quality of the partial discharges having caused the pulses, wherein the detection coil is adapted to process signals with a frequency higher than 100 MHZ, characterized in that the detection coil comprises a one turn, and that the detection coil is made of strip-shaped of rectangular cross section metal.
Claim 2
Dependent Claim
138 words
Method for detecting partial discharges occurring in a cable, wherein the cable has a core and an earth shield with a helical structure, comprising the following steps of: arranging at least one detection coil around the cable so as not to locally destruct the cable and for detecting electromagnetic pulses traveling along the cable; applying a potential difference between the core and the earth shield of the cable; and analyzing pulses generated by possible partial discharges in at least one detection coil in order to determine the location and quality of the partial discharges having caused the pulses, wherein the detection coil is adapted to process signals with a frequency higher than 100 MHZ, characterized in that the detection coil comprises a one turn, and that the detection coil is made of strip-shaped of rectangular cross section metal.
Claim 3
Dependent Claim
40 words
Method as claimed in claim 1, characterized in that two detection coils placed at a mutual distance are used and that the location of the partial discharge is derived from the delay between the pulses detected on both detection coils.
Claim 4
Dependent Claim
50 words
Method as claimed in claim 1, characterized in that after detection of a first partial discharge at least one detection coil is displaced to the location where, according to calculation, the discharge takes place, and the measurement is subsequently repeated and the location derived from the polarity of the signal.
Claim 5
Dependent Claim
39 words
Method as claimed in claim 1, characterized in that the signal coming from the detection coils is recorded with a digitizer and thereafter analyzed, or is analyzed by means of high-speed electronic equipment (TAC-discriminator) as to amplitude and delay.
References Cited (Backward Citations)
US1931225A
Cited
GB539904A
Cited
US3657650A
Cited
US3743922A
Cited
US4446420A
Cited
US4804917A
Cited
EP0390034A2
Cited
EP0424598A2
Cited
US5416418A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-06-15 | 2001-12-15 | 2002-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-06-15 | 2005-12-15 | 2006-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-06-15 | 2009-12-15 | 2010-06-16 | $7700.00 | Window Closed / Lapsed |