Partial discharge detection method

• US 6,297,642 B1
• Filed: 05/11/1999
• Issued: 10/02/2001
• Est. Priority Date: 05/12/1998
• Status: Expired due to Fees

• Current Assignee: Nissin Electric Company Limited (Sumitomo Corporation)
• Original Assignee: Nissin Electric Company Limited (Sumitomo Corporation)
• Inventors: Watanabe, Yoshihiro, Shibahara, Kazuhito, Sumiyoshi, Masahiro
• Primary Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US09/309,605
• Time in Patent Office: 875 Days
• Field of Search: 324/509, 324/510, 324/511, 324/520, 324/536, 324/551, 324/457, 324/122
• US Class Current: 324/536
• CPC Class Codes: G01R 31/1227 of components, parts or materials G01R31/1209, G01R31/1218, G01R31/18 take precedence; circuits therefor G01R31/14; testing vessels of electrodes G01R31/16

Abstract

An electromagnetic waveform developing in synchronism with a system power supply by a partial discharge of electric equipment such as a power distribution device is received by an antenna 1. From the electromagnetic waveform of measurement frequency included in the received signal, there are extracted a component changing according to the frequency of the system power supply and a component changing at the frequency twice that of the system power supply. The presence or absence of discharge is determined from the magnitude of each of the extracted components, thereby detecting a partial discharge.

Claims

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

receiving an electromagnetic signal generated by at least one piece of electric equipment,

determining a measurement frequency of the signal to diminish the frequency characteristics of background noise;

extracting a component of the measurement frequency modulating at the frequency of a system power supply of the electric equipment; and

detecting a partial discharge based on the extracted component.

2. A partial discharge detection method according to claim 1, wherein the signal is received by an antenna.

3. A partial discharge detection method according to claim 1, wherein the partial discharge is detected based on a magnitude of the extracted component.

4. A partial discharge detection method according to claim 1, wherein the partial discharge is detected based on a strength ratio of the extracted component to the background noise of the signal.

5. A partial discharge detection method according to claim 1, wherein the step of detecting the partial discharge further comprises:

measuring a magnitude of the extracted component; and

measuring a strength ratio of the extracted component to the background noise of the signal, wherein the partial discharge is detected when either the magnitude of the extracted component is greater than a first threshold value or the strength ratio of the extracted component is greater than a second threshold value.

6. A partial discharge detection method according to claim 1, wherein the extracted component is an effective value of electromagnetic energy.

7. A partial discharge detection method comprising the steps of:

receiving an electromagnetic signal generated by at least one piece of electric equipment;

determining a measurement frequency of the signal to diminish the frequency characteristics of background noise;

extracting a first component of the measurement frequency, wherein the first component is modulating at the frequency of a system power supply of the electric equipment;

extracting a second component of the measurement frequency, wherein the second component is modulating at twice the frequency of the system power supply; and

detecting a partial discharge based on the extracted components.

8. A partial discharge detection method according to claim 7, further comprising measuring a magnitude of the first and second components, wherein a partial discharge is detected when either the first component is greater than a first threshold value of the second component is greater than a second threshold value.

9. A partial discharge detection method according to claim 7, wherein the partial discharge is detected from the sum of the first and second components.

10. A partial discharge detection method according to claim 7, further comprising:

determining a strength ratio of the first component to the background noise of the signal; and

determining a strength ratio of the second component to the background noise of the signal, wherein the partial discharge is detected when either the strength ratio of the first component is greater than a third threshold value or the strength ratio of the second component is greater than a fourth threshold value.

11. A partial discharge detection method according to claim 7, further comprising:

determining a magnitude of the first component;

determining a magnitude of the second component;

determining a sum of the magnitudes of the first and second components;

determining a strength ratio of the first component to the background noise of the signal;

determining a strength ration of the second component to the background noise of the signal; and

determining a strength ratio of the sum of the first and second components to the background noise of the signal wherein the partial discharge is detected when any of the magnitudes or strength ratios is determined to be greater than its respective threshold value.

12. A partial discharge detection method according to claim 7, wherein the extracted component of the first and second components are effective values of electromagnetic energy.