Apparatus for monitoring degradation of insulation of electrical installation
First Claim
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1. An apparatus for monitoring degradation of insulation of an electrical installation comprising:
- a first sensor for detecting a progressive wave generated by a partial discharge taking place at a location where the insulation is degraded in the power transmission paths;
a second for detecting the phase of said generated progressive wave as well as external noise;
a third sensor for detecting a reference signal for determining the direction of said progressive wave; and
a measurement section for processing the signals from said first sensor, second sensor and third sensor;
wherein said measurement section determines existence or non-existence of degraded insulation by comparing the phases of the signals from the first sensor and the third sensor when it detects a progressive wave generated at a location where degradation of insulation of an electric cable or an electric equipment is taking place, and it also determines if the signal from the second sensor represents an external noise or degraded insulation and detects the phase of degradation if degraded insulation is involved;
capacitors being arranged between common buses connected with a power cable and ground for each phase of the buses;
said first sensor being adapted to detect progressive waves in a power cable comprising a plurality of power transmission paths;
said second sensor being adapted to detect the phase of progressive waves in lines connecting the capacitors to the ground for each different phase;
said third sensor being adapted to detect a reference signal in lines connecting all the capacitors to the ground,each of said first, second and third sensors being formed by arranging a detection winding around an annular core and placing an object of detecting operation through the annular core, said object of detecting operation constituting its primary winding,said measurement section does not proceed with the operation of detecting degradation of insulation caused by a progressive wave once the signal from the second sensor is determined to represent external noise, andeach of the annular cores of said first, second and third sensors showing roughly linear BH characteristics representing a roughly proportional relationship between its magnetomotive force and magnetic flux density and an almost constant magnetic permeability over the entire frequency range from low to high frequency regions.
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Abstract
According to the invention, there is provided an apparatus for monitoring degradation of insulation of an electrical installation that can constantly monitor its electric equipments and cables for degradation of insulation under hot-line conditions. Said apparatus comprises:
a first sensor for detecting a progressive wave generated by a partial discharge taking place at a location where the insulation is degraded in the power transmission paths;
a second sensor for detecting the phase of said generated progressive wave as well as external noise;
a third sensor for detecting a reference signal for determining the direction of said progressive wave; and
a measurement section for processing the signals from the first sensor, second sensor and third sensor;
wherein said measurement section determines existence or non-existence of degraded insulation by comparing the phases of the signals from the first sensor and the third sensor when it detects a progressive wave generated at a location where degradation of insulation of an electric cable or an electric equipment is taking place, and it also determines if the signal from each of the second sensor represents an external noise or degraded insulation and detects the phase of degradation if degraded insulation is involved.
33 Citations
11 Claims
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1. An apparatus for monitoring degradation of insulation of an electrical installation comprising:
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a first sensor for detecting a progressive wave generated by a partial discharge taking place at a location where the insulation is degraded in the power transmission paths; a second for detecting the phase of said generated progressive wave as well as external noise; a third sensor for detecting a reference signal for determining the direction of said progressive wave; and a measurement section for processing the signals from said first sensor, second sensor and third sensor; wherein said measurement section determines existence or non-existence of degraded insulation by comparing the phases of the signals from the first sensor and the third sensor when it detects a progressive wave generated at a location where degradation of insulation of an electric cable or an electric equipment is taking place, and it also determines if the signal from the second sensor represents an external noise or degraded insulation and detects the phase of degradation if degraded insulation is involved; capacitors being arranged between common buses connected with a power cable and ground for each phase of the buses; said first sensor being adapted to detect progressive waves in a power cable comprising a plurality of power transmission paths; said second sensor being adapted to detect the phase of progressive waves in lines connecting the capacitors to the ground for each different phase; said third sensor being adapted to detect a reference signal in lines connecting all the capacitors to the ground, each of said first, second and third sensors being formed by arranging a detection winding around an annular core and placing an object of detecting operation through the annular core, said object of detecting operation constituting its primary winding, said measurement section does not proceed with the operation of detecting degradation of insulation caused by a progressive wave once the signal from the second sensor is determined to represent external noise, and each of the annular cores of said first, second and third sensors showing roughly linear BH characteristics representing a roughly proportional relationship between its magnetomotive force and magnetic flux density and an almost constant magnetic permeability over the entire frequency range from low to high frequency regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification
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Current AssigneeMitsui Chemicals Incorporated (Mitsui Chemicals)
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Original AssigneeMitsui Petrochemical Industries, Ltd.
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InventorsKageyama, Tomoaki, Maezawa, Shigenari, Sera, Akio, Terunaga, Fukuso, Saigo, Akira
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Primary Examiner(s)Wieder, Kenneth A.
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Assistant Examiner(s)Regan, Maura K.
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Application NumberUS07/560,722Time in Patent Office665 DaysField of Search324/521, 324/522, 324/529, 324/536, 324/541, 324/544, 324/551, 333/177, 333/25, 333/32US Class Current324/551CPC Class CodesG01R 31/1272 of cable, line or wire insu...G01R 31/58 Testing of lines, cables or...
