Method and device for detecting a partial discharge in an electrical device

• US 20020024341A1
• Filed: 06/08/2001
• Published: 02/28/2002
• Est. Priority Date: 08/28/2000
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Rokunohe, Toshiaki, Yatsuzuka, Hirohiko
• Granted Patent: US 6,661,235 B2
• Time in Patent Office: Days
• US Class Current: 324/536
• CPC Class Codes: G01R 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083
• CPC Class Codes: H01H 33/26 Means for detecting the presence of an arc or other discharge

Abstract

The present invention provides a method and device for detecting a discharge in an electrical device comprising, providing a bushing having a bottom lower flange and a top upper flange, providing a shield inside the bushing extending from the bottom lower flange to a position at least below the top upper flange and providing an antenna outside the bushing at least above the position for measuring an output signal from the device for detecting the discharge.

Claims

1. A method for detecting a discharge in an electrical device, comprising the acts of:

providing a bushing having a bottom lower flange and a top upper flange;

providing a shield inside said bushing extending from said bottom lower flange to a position at least below said top upper flange; and

providing an antenna outside said bushing at least above said position for measuring an output signal from said device for detecting said discharge.

2. The method of claim 1 further comprising the act of utilizing a frequency of about 100 Mhz to about 1500 Mhz in said output signal for said detection.

3. The method of claim 1 further comprising the act of utilizing a change in periodicity of said output signal for said detection.

4. The method of claim 1 wherein said position is located above said lower flange at about 3-20% of the distance between said bottom lower flange and said top upper flange.

5. The method of claim 1 wherein said antenna is a dipole antenna.

6. The method of claim 1 wherein said antenna is a folded dipole antenna.

7. The method of claim 1 wherein said antenna is a slit antenna.

8. The method of claim 1 wherein said antenna is a loop antenna.

9. The method of claim 1 further comprising the act of providing a ground electrode adjacent said antenna for preventing induced potential.

10. The method of claim 1 further comprising the act of providing a ground electrode surrounding said antenna for preventing induced potential.

11. The method of claim 1 wherein said electrical device is a gas insulating device.

13. The method of claim 12 further comprising the act of utilizing a frequency of about 100 Mhz to about 1500 Mhz in said output signal for said detection.

14. The method of claim 12 further comprising the act of utilizing a change in periodicity of said output signal for said detection.

15. The method of claim 12 wherein said antenna is a dipole antenna.

16. The method of claim 12 wherein said antenna is a folded dipole antenna.

17. The method of claim 12 wherein said antenna is a slit antenna.

18. The method of claim 12 wherein said antenna is a loop antenna.

19. The method of claim 12 further comprising the act of providing a ground electrode adjacent said antenna for preventing induced potential.

20. The method of claim 12 further comprising the act of providing a ground electrode surrounding said antenna for preventing induced potential.

21. The method of claim 12 wherein said electrical device is a gas insulating device.

12. A method for detecting a discharge in an electrical device, comprising the acts of:

providing a bushing having a bottom lower flange and a top upper flange;

providing an antenna outside said bushing at a position for measuring an output signal from said device for detecting said discharge; and

said position being located above said bottom lower flange at about 3-20% of the distance between said bottom lower flange and said top upper flange.

22. A discharge detector for an electrical device, comprising:

a bushing having a bottom lower flange and a top upper flange;

a shield inside said bushing extending from said bottom lower flange to a position at least below said top upper flange; and

an antenna located outside said bushing at least above said position for measuring an output signal from said device for detecting said discharge.

23. The detector of claim 22 wherein said position is located above said bottom lower flange at about 3-20% of the distance between said bottom lower flange and said top upper flange.

24. The detector of claim 22 wherein said antenna is a dipole antenna.

25. The detector of claim 22 wherein said antenna is a folded dipole antenna.

26. The detector of claim 22 wherein said antenna is a slit antenna.

27. The detector of claim 22 wherein said antenna is a loop antenna.

28. The detector of claim 22 further comprising a ground electrode adjacent said antenna for preventing induced potential.

29. The detector of claim 22 further comprising a ground electrode surrounding said antenna for preventing induced potential.

30. The detector of claim 22 wherein said electrical device is a gas insulating device.

31. A discharge detector for an electrical device, comprising :

a bushing having a bottom lower flange and a top upper flange;

an antenna outside said bushing at a position for measuring an output signal from said device for detecting said discharge; and

said position being located above said bottom lower flange at about 3-20% of the distance between said bottom lower flange and said top upper flange.

32. The detector of claim 31 wherein said antenna is a dipole antenna.

33. The detector of claim 31 wherein said antenna is a folded dipole antenna.

34. The detector of claim 31 wherein said antenna is a slit antenna.

35. The detector of claim 31 wherein said antenna is a loop antenna.

36. The detector of claim 31 further comprising a ground electrode adjacent said antenna for preventing induced potential.

37. The detector of claim 31 further comprising a ground electrode surrounding said antenna for preventing induced potential.

38. The detector of claim 31 wherein said electrical device is a gas insulating device.