EP0424598A2
Expired / Lapsed
EP
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Method for detecting partial discharge in an insulation of an electric power cable
Assignee: Hitachi Cable Ltd
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Filing: 1990-01-31
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Granted: —
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Expires: 2010-01-31
Abstract
Abstract In an electric apparatus such as an electric power cable system, a high frequency pulse is induced on a conductive member such as a metal sheath, where partial discharge occurs in an insulation. The high frequency pulse is detected by means of a bypass lead wire, a metal foil electrode, a detecting coil, and the like provided on the electric apparatus without interrupting a live operation of the electric apparatus.
Inventors
- 👤 Takeshi C/O Cable Laboratory Endoh
- 👤 Tomoaki C/O Hitaka Works Imai
- 👤 Mikio C/O Cable Laboratory Hagiya
- 👤 Chuki C/O Cable Laboratory Ikeda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 18:22
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/08; G01R31/081; G01R31/083; G01R31/12; G01R31/1227; G01R31/1263; G01R31/1272; G01R31/50; G01R31/58
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
80 words
A method for detecting partial discharge in an insulation of an electric apparatus, comprising: providing a magnetic core having a predetermined inductance around a lead wire, through which a high frequency pulse induced by said partial discharge flows; connecting a detecting lead wire in parallel to said lead wire, said high frequency pulse thereby being bypassed through said detecting lead wire; and detecting said high frequency pulse flowing through said detecting lead wire to diagnose a degradation of said insulation.
Claim 2
Independent Claim
80 words
A method for detecting partial discharge in an insulation of an electric apparatus, comprising: providing a magnetic core having a predetermined inductance around a lead wire, through which a high frequency pulse induced by said partial discharge flows; connecting a detecting lead wire in parallel to said lead wire, said high frequency pulse thereby being bypassed through said detecting lead wire; and detecting said high frequency pulse flowing through said detecting lead wire to diagnose a degradation of said insulation.
Claim 3
Independent Claim
72 words
A method for detecting partial discharge in an insulation of an electric apparatus, comprising: providing a detecting electrode for a capacitive coupling on a conductive member, on which a high frequency pulse is induced by said partial discharge, to provide a capacitor; and introducing said high frequency pulse through said detecting electrode to a partial discharge detecting apparatus, in which said partial discharge is detected to diagnose a degradation of said insulation.
Claim 4
Independent Claim
72 words
A method for detecting partial discharge in an insulation of an electric apparatus, comprising: providing a detecting electrode for a capacitive coupling on a conductive member, on which a high frequency pulse is induced by said partial discharge, to provide a capacitor; and introducing said high frequency pulse through said detecting electrode to a partial discharge detecting apparatus, in which said partial discharge is detected to diagnose a degradation of said insulation.
Claim 5
Dependent Claim
54 words
A method for detecting partial discharge in an insulation of an electric apparatus, according to claim 2, wherein: said electric apparatus is an electric power cable having a metal sheath; said detecting electrode is an isolated metal sheath section which is formed by removing said metal sheath on both sides of said isolated section.
Claim 6
Dependent Claim
45 words
A method for detecting partial discharge in an insulation of an electric apparatus, according to claim 3, further comprising: an auxiliary electrode facing a plastic sheath provided on said isolated section, said auxiliary electrode supplying said partial discharge detecting signal with said high frequency pulse.
Claim 7
Independent Claim
89 words
A method for detecting partial discharge in an insulation of an electric apparatus, comprising: separating conductive member sections, on which a high frequency pulse is induced by said partial discharge; detecting said partial discharge by connecting a detecting impedance between said separated conductive member sections; said detecting impedance being connected to a partial discharge detecting apparatus, in which said partial discharge is detected to diagnose a degradation of said insulation; and connecting a calibration pulse generator in parallel with said detecting impedance to calibrate said partial discharge detecting apparatus.
Claim 8
Independent Claim
89 words
A method for detecting partial discharge in an insulation of an electric apparatus, comprising: separating conductive member sections, on which a high frequency pulse is induced by said partial discharge; detecting said partial discharge by connecting a detecting impedance between said separated conductive member sections; said detecting impedance being connected to a partial discharge detecting apparatus, in which said partial discharge is detected to diagnose a degradation of said insulation; and connecting a calibration pulse generator in parallel with said detecting impedance to calibrate said partial discharge detecting apparatus.
Claim 9
Dependent Claim
39 words
A method for detecting partial discharge in an insulation of an electric apparatus, according to claim 5, wherein: said electric apparatus is an electric power cable; and said conductive member is a metal sheath of said electric power cable.
Claim 10
Dependent Claim
44 words
A method for detecting partial discharge in an insulation of an electric apparatus, according to claim 5, wherein: said electric apparatus is an electric power cable; said separated conductive member sections are metal sheaths separated in an insulating joint of said electric power cable.
Claim 11
Dependent Claim
41 words
A method for detecting partial discharge in an insulation of an electric apparatus, according to claim 7, further comprising: a pair of detecting electrodes provided on a plastic anti-corrosion layer covering said separated metal sheaths, and connected to said detecting impedance.
Claim 12
Dependent Claim
47 words
A method for detecting partial discharge in an insulation of an electric apparatus, according to claim 8, further comprising: a pair of calibrating electrodes provided on said plastic anti-corrosion layer to be adjacent to said pair of said detecting electrodes, and connected to said calibration pulse generator.
Claim 13
Independent Claim
82 words
a method for detecting partial discharge in an insulation of an electric apparatus, comprising: detecting a frequency spectrum of noise obtained from said electric apparatus; detecting a frequency spectrum of an output signal obtained from said electric apparatus, to which a calibration pulse is supplied: comparing said frequency spectrums of said noise and said output signal to provide a frequency, at which a predetermined signal to noise ratio is obtained; and detecting said partial discharge of said electric apparatus at said frequency.
Claim 14
Independent Claim
82 words
a method for detecting partial discharge in an insulation of an electric apparatus, comprising: detecting a frequency spectrum of noise obtained from said electric apparatus; detecting a frequency spectrum of an output signal obtained from said electric apparatus, to which a calibration pulse is supplied: comparing said frequency spectrums of said noise and said output signal to provide a frequency, at which a predetermined signal to noise ratio is obtained; and detecting said partial discharge of said electric apparatus at said frequency.
Claim 15
Dependent Claim
44 words
A method for detecting partial discharge in an insulation of an electric apparatus, according to claim 10, wherein: said electric apparatus is an electric power cable; and said calibration pulse is supplied between a conductor and a metal sheath of said electric power cable.
Claim 16
Dependent Claim
55 words
A method for detecting partial discharge in an insulation of an electric apparatus, according to claim 11, wherein: said calibration pulse is supplied to said electric power cable at an appropriate position which is selected from a terminal joint, an insulating joint, a normal joint, and a longitudinally selected portion of said electric power cable.
Claim 17
Independent Claim
53 words
A method for detecting partial discharge in an insulation of a wire shielded electric power cable, comprising: providing a detecting coil around said wire shielded electric power cable; and detecting said partial discharge in accordance with an electromagnetic coupling between said detecting coil and shielding wires of said wire shielded electric power cable.
Claim 18
Independent Claim
53 words
A method for detecting partial discharge in an insulation of a wire shielded electric power cable, comprising: providing a detecting coil around said wire shielded electric power cable; and detecting said partial discharge in accordance with an electromagnetic coupling between said detecting coil and shielding wires of said wire shielded electric power cable.
Claim 19
Dependent Claim
34 words
a method for detecting partial discharge in an insulation of a wire shielded electric power cable, according to claim 13, wherein: said detecting is carried out at a frequency of more than 10 KHz.
Claim 20
Dependent Claim
34 words
A method for detecting partial discharge in an insulation of wire shielded electric power cable, according to claim 13, further comprising: a high frequency steel core which is provided to cover said detecting coil.
Claim 21
Dependent Claim
54 words
A method for detecting partial discharge in an insulation of a wire shielded electric power cable, according to claim, according to claim 13, further comprising: a high frequency steel core which is positioned to be adjacent to said wire shielded electric power cable, said detecting coil is wound around said high frequency steel core.
Claim 22
Independent Claim
86 words
A method for detecting partial discharge in an insulation of an electric power cable line, comprising: detecting signal intensities of said partial discharge at least three different positions of said electric power cable line; and locating a position of a maximum value in signal intensity in accordance with the increased and decreased inclinations of said signal intensities in a longitudinal direction of said electric power cable line, said position of said maximum value is determined to be a place where said discharge occurs in said insulation.
Claim 23
Independent Claim
86 words
A method for detecting partial discharge in an insulation of an electric power cable line, comprising: detecting signal intensities of said partial discharge at least three different positions of said electric power cable line; and locating a position of a maximum value in signal intensity in accordance with the increased and decreased inclinations of said signal intensities in a longitudinal direction of said electric power cable line, said position of said maximum value is determined to be a place where said discharge occurs in said insulation.
References Cited (Backward Citations)
No citation records indexed.
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