Insulated device diagnosing system that prepares detection data from partial discharge signal such that periodic elements are given to different specific frequencies of the partial discharge signal

• US 6,424,162 B1
• Filed: 08/11/1999
• Issued: 07/23/2002
• Est. Priority Date: 12/09/1996
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Rokunohe, Toshiaki, Endo, Fumihiro, Yamagiwa, Tokio, Shinohara, Ryouichi
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Hamdan, Wasseem H.
• Application Number:
  US09/372,139
• Time in Patent Office: 1,077 Days
• Field of Search: 324/551, 324/536, 324/522, 324/520, 702/58, 702/185, 702/59, 340/644, 736/59
• US Class Current: 324/551
• CPC Class Codes: G01R 31/1254 of gas-insulated power appliances or vacuum gaps testing switches G01R31/327; detecting electrical or mechanical defects in encased switchgear H02B13/065
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults

Abstract

An insulated device diagnosing system is capable of judging the deterioration, lifetime, and defects of a device. The intensity at each voltage phase angle is measured at a plurality of specific frequencies, taking high voltage phase angles as the abscissas. The deterioration, lifetime, and the kind and extent of abnormality of the device are judged from the pattern and intensity of the spectral distribution, which is obtained by peak-holding the measured intensity for a defined time period. According to the present invention, partial discharge can be measured highly sensitively and precisely to diagnose the deterioration, lifetime and the extent of defect of the device. As a result, the insulation reliability of the device can be improved, and the part of the device that should be repaired/replaced can be grasped before disassembly of the device, thereby cutting the maintenance cost.

Claims

1. A partial discharge detecting method comprising the steps of:

inputting a partial discharge signal resulting from a partial discharge of an insulated device from an input terminal;

determining an intensity in which said partial discharge signal is expanded for each frequency by an FFT or a spectral analyzer to select a plurality of different specific frequencies from frequencies having high intensities, detecting the intensity of each frequency of said partial discharge signal to select a plurality of specific frequencies, of which the intensities exceed a predetermined value, or selecting the frequency having the highest intensity from the specific frequencies;

preparing detection data from the partial discharge signal which are given periodic elements at a specific frequency selected; and

processing at least one of said detection data or displaying the detection data on a screen to detect the partial discharge.

2. A partial discharge detecting method according to claim 1, wherein an extent or kind of abnormality, deterioration, or lifetime of the insulated device is diagnosed by processing said detection data by a neuro computer method or by a finger printing method.

3. A partial discharge detecting method comprising the steps of:

inputting a partial discharge signal of an insulated device from an input terminal;

preparing detection data from the partial discharge signal such that a plurality of different specific frequencies of the partial discharge signal are given periodic elements;

preparing sampling data by differentiating either averaged data averaged from detection data of different frequencies or known data from the individual detection data, or by differentiating the intensities of the detection data detected by antennas provided in different positions of the insulated device, between identical frequencies; and

diagnosing an extent of abnormality, a deterioration or a lifetime of the device from the pattern or the intensities of the prepared sampling data.

4. An insulated device diagnosing system comprising:

a plurality of antennas provided in an insulated device;

a pattern generator for receiving partial discharge signals, resulting from a partial discharge in the insulated device, from said antennas, and preparing detection data from the partial discharge signals such that periodic elements are given to a plurality of different specific frequencies of the partial discharge signals;

a neuro computer or a finger printing method operation unit for processing the detection data prepared by said pattern generator; and

a judgment unit for diagnosing the extent of abnormality, a deterioration or a lifetime of said device from the operation result of said neuro computer or finger printing method operation unit;

wherein said insulated device is a gas insulated breaker;

wherein said partial discharge signals come from said plurality of antennas, which are provided at different positions in said gas insulated device, and said partial discharge signals are measured synchronously; and

wherein the partial discharge is located from the spectral patterns or intensity ratios of said detection data between the same frequencies.

5. An insulated device diagnosing system comprising:

a plurality of antennas provided in an insulated device;

a pattern generator for receiving partial discharge signals, resulting from a partial discharge of the insulated device, from said antennas, and preparing detection data from the partial discharge signals such that periodic elements are given to a plurality of different specific frequencies of the partial discharge signals;

a neuro computer or a finger printing method operation unit for processing the detection data prepared by said pattern generator; and

a judgment unit for diagnosing the extent of abnormality, a deterioration or a lifetime of said device from the operation result of said neuro computer or finger printing method operation unit;

wherein a distribution of frequency components of the partial discharge signals is also measured for specifying the different specific frequencies to be detected; and

wherein said insulated device is a gas insulated breaker;

wherein said partial discharge signals come from said plurality of antennas, which are provided at different positions in said gas insulated device, and said partial discharge signals are measured synchronously; and

wherein the partial discharge is located from the spectral patterns or intensity ratios of said detection data between the same frequencies.