Method and system for detecting core faults

• US 6,469,504 B1
• Filed: 07/28/2000
• Issued: 10/22/2002
• Est. Priority Date: 07/28/2000
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Shah, Manoj Ramprasad, Kliman, Gerald Burt, Mallick, John Andrew
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): LEROUX, ETIENNE PIERRE
• Application Number:
  US09/575,715
• Time in Patent Office: 816 Days
• Field of Search: 324/228, 324/233, 324/239, 324/240, 324/545
• US Class Current: 324/228
• CPC Class Codes: G01N 27/9006 Details, e.g. in the structure or functioning of sensors
• CPC Class Codes: G01R 31/34 Testing dynamo-electric machines

Abstract

A method for detecting core faults includes (a) positioning a magnetic yoke near at least one tooth of the core, the magnetic yoke being wound by a winding; (b) supplying current to the winding to inject magnetic flux into the at least one tooth of the core; (c) measuring a signal resulting from the injected magnetic flux; and (d) using the measured signal to detect core faults.

Claims

1. A method for detecting core faults comprising:

(a) positioning a magnetic yoke near two non-adjacent teeth of the core, the magnetic yoke being wound by a winding;

(b) supplying current to the winding to inject magnetic flux into the two non-adjacent teeth;

(c) measuring a signal resulting from the injected magnetic flux; and

(d) using the measured signal to detect core faults.

2. The method of claim 1 wherein (a) comprises positioning the magnetic yoke near two teeth.

3. The method of claim 2 wherein (a) comprises positioning the magnetic yoke near two adjacent teeth.

8. The method of claim 1 further comprising repeating (a)-(c) and using the plurality of resulting measured signals to detect core faults in (d).

9. The method of claim 1 wherein (a) comprises positioning the magnetic yoke near one tooth.

10. The method of claim 9 wherein (a) comprises positioning the magnetic yoke around the one tooth.

13. The method of claim 1 further comprising repeating (a)-(c) and using the plurality of resulting measured signals to detect core faults in (d).

14. The method of claim 13 wherein, when repeating (a)-(c), positioning comprises axially moving the magnetic yoke relative to the at least one tooth.

4. A method for detecting core faults comprising:

(a) positioning a magnetic yoke near exactly one tooth of the core, the magnetic yoke being wound by a winding;

(b) supplying current to the winding to inject magnetic flux into the tooth;

(c) measuring a signal resulting from the injected magnetic flux; and

(d) using the measured signal to detect core faults.

5. The method of claim 4 wherein (a) comprises positioning the magnetic yoke around the tooth.

6. The method of claim 5 wherein the magnetic yoke further includes a shorting element contacting and shorting laminations of the tooth.

7. The method of claim 6 wherein the magnetic yoke further includes a shorting element contacting at least one tooth between the two non-adjacent teeth and shorting laminations of the at least one tooth.

11. A method for detecting core faults comprising:

(a) positioning a magnetic yoke near at least one tooth of the core, the magnetic yoke being wound by a winding;

(b) supplying current having an arbitrary waveform to the winding to inject magnetic flux into the at least one tooth of the core;

(c) measuring a plurality of signals resulting from the injected magnetic flux; and

(d) using the plurality of resulting measured signals to detect core faults.

12. The method of claim 11 further including detecting voltage or current from the shorting element.

15. A method for detecting core faults comprising:

(a) repeating, at different positions of the core,

(1) positioning a magnetic yoke near two teeth of the core, the magnetic yoke being wound by a winding;

(2) supplying current of varying frequency to the winding in inject magnetic flux into the two teeth of the core; and

(3) measuring a plurality of signals resulting from the injected magnetic flux; and

(b) using the plurality of resulting measured signals to detect core faults.

16. A method for detecting core faults comprising:

(a) repeating, at different positions of the core,

(1) positioning a magnetic yoke near two teeth of the core, the magnetic yoke being wound by a winding;

(2) supplying current of varying magnitude to the winding to inject magnetic flux into the two teeth of the core;

(3) measuring a plurality of signals resulting from the injected magnetic flux; and

(b) using the plurality of resulting measured signals to detect core faults.

17. The system of claim 16 wherein the at least one magnetic yoke comprises a bar-shaped yoke.

18. A system for detecting core faults comprising:

(a) at least one magnetic yoke wound by a winding and adapted for being positioned near two non-adjacent teeth of the core;

(b) a current supply for supplying current to the winding to inject magnetic flux into the two non-adjacent teeth of the core;

(c) a sensor for measuring a signal resulting from the injected magnetic flux; and

(d) a computer for using the measured signal to detect core faults.

19. The method of claim 18 wherein (b) comprises supplying sharply cut off pulses, and (c) comprises measuring the time rate of decay of the resulting measured signals.

21. The system of claim 18 wherein the at least one magnetic yoke is adapted for being positioned at any of a number of angles.

20. A method for detecting core faults comprising:

(a) repeating, at different positions of the core, (1) positioning a magnetic yoke near two teeth of the core, the magnetic yoke being wound by a winding;

(2) supplying current to the winding to inject magnetic flux into the two teeth of the core; and

(3) measuring a signal resulting from the injected magnetic flux; and

(b) using the measured signals to detect core faults.

22. A system for detecting core faults comprising:

(a) at least one magnetic yoke wound by a winding for being positioned near at least one tooth of the core;

(b) a current supply for supplying current to the winding to inject magnetic flux into the at least one tooth of the core;

(c) a sensor for measuring a signal resulting from the injected magnetic flux; and

(d) a computer for using the measured signal to detect core faults.

27. The system of claim 22 the at least one magnetic yoke is adapted for being positioned near two adjacent teeth.

28. The system of claim 22 wherein the at least one magnetic yoke is adapted for being positioned near two non-adjacent teeth.

29. The system of claim 28 wherein the at least one magnetic yoke further includes a shorting element contacting at least one tooth between the two non-adjacent teeth and shorting laminations of the at least one tooth.

30. The system of claim 29 further including leads for transmitting voltage or current from the shorting element.

31. The system of claim 27 wherein the at least one magnetic yoke is adapted for being positioned at any of a number of angles.

23. A system for detecting core faults comprising:

(a) at least one magnetic yoke wound by a winding and adapted for being positioned near exactly one tooth;

(b) a current supply for supplying current to the winding to inject magnetic flux into the tooth;

(c) a sensor for measuring a signal resulting from the injected magnetic flux; and

(d) a computer for using the measured signal to detect core faults.

24. The system of claim 23 wherein the at least one magnetic yoke is adapted for being positioned around the tooth.

25. The system of claim 24 wherien the magnetic yoke further includes a shorting element contacting and shorting laminations of the tooth.

26. A system for detecting core faults comprising:

(a) at least one magnetic yoke wound by a winding for being positioned near at least one tooth of the core;

(b) a current supply adapted to supply a current having an arbitrary waveform to the winding to inject magnetic flux into the at least one tooth of the core;

(c) a sensor for measuring a signal resulting from the injected magnetic flux; and

(d) a computer for using the measured signal to detect core faults.

33. The system of claim 26 wherein the sensor comprises a vibration sensor.

32. A method for stacking a core comprising:

(a) forming a stack of a plurality of core laminations;

(b) positioning a magnetic yoe near at least one tooth of the stack, the magnetic yoke being wound by a winding;

(c) supplying current to the winding to inject magnetic flux into the at least one tooth;

(d) measuring a signal resulting from the injected magnetic flux;

(e) using the measured signal to detect core faults;

(f) if no core faults are detected in the stack, using the stack as part of the core, and if core faults are detected, not using the stack as port of the core; and

(g) forming an additional stack of a plurality of core laminations and repeating (b)-(f) for the additional stack.