Motor bearing damage detection via wavelet analysis of the starting current transient

• US 6,727,725 B2
• Filed: 05/01/2001
• Issued: 04/27/2004
• Est. Priority Date: 05/01/2001
• Status: Active Grant

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Eren, Levent, Devaney, Michael J.
• Primary Examiner(s): Cuneo, Kamand
• Assistant Examiner(s): HOLLINGTON, JERMELE M
• Application Number:
  US09/846,865
• Publication Number:
  US 20020186039A1
• Time in Patent Office: 1,092 Days
• Field of Search: 324/772, 324/545, 324/725, 318/245, 318/490, 702/34, 702/56, 702/54
• US Class Current: 324/765.01
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis
• CPC Class Codes: G01R 31/343 in operation

Abstract

An apparatus and method for detecting motor bearing defects obtains motor current transient data during motor start-up, analyzes the motor current transient data via discrete wavelet transform, and compares the wavelet sub-bands to a baseline signature of a bearing-defect-free motor to detect bearing defects.

Claims

1. A method for detecting motor bearing defects, said method comprising:

obtaining motor current transient data during motor start-up; and

analyzing in a processor said motor current transient data to determine changes in RMS levels due to bearing defect-induced resonance.

2. The method of claim 1 and further including selecting data in one or more frequency bands.

3. The method of claim 1 wherein said analyzing comprises using a wavelet transform analysis.

4. The method of claim 1 wherein said analyzing comprises comparing the data to start-up data corresponding to a nondefective bearing.

5. The method of claim 1 wherein said analyzing comprises comparing data selected from two or more frequency sub-bands.

6. The method of claim 1 wherein said analyzing comprises determining a ratio of start-up RMS in one or more cycles to steady state RMS under different loading conditions of said motor bearing.

7. The method of claim 1 wherein said analyzing includes selecting a data occurring at one or more cycles of alternating current.

8. The method of claim 7 and further including selecting data in one or more frequency bands.

9. The method of claim 1 wherein said obtaining comprises obtaining motor current transient readings at a plurality of points per cycle of alternating current.

10. The method of claim 9 wherein said plurality of said points comprises 512 or more points.

11. An apparatus for detecting motor bearing defects, said apparatus comprising:

means for obtaining motor current transient data during motor start-up; and

means for analyzing in a processor said motor current transient data to determine whether changes in RMS levels are due to bearing defect-induced resonance.

12. The apparatus of claim 11 and further including means for selecting data in one or more frequency bands.

13. The apparatus of claim 11 wherein said means for analyzing uses a wavelet transform analysis.

14. The apparatus of claim 11 wherein said means for analyzing comprises means for comparing the data to start-up data corresponding to a nondefective bearing.

15. The apparatus of claim 11 wherein said means for analyzing comprises means for comparing data selected from two or more frequency sub-bands.

16. The apparatus of claim 11 wherein said means for analyzing comprises means for determining a ratio of start-up RMS in one or more cycles to steady state RMS under different loading conditions of said motor bearing.

17. The apparatus of claim 11 wherein said means for analyzing includes means for selecting data occurring at one or more cycles of alternating current.

18. The apparatus of claim 17 and further including means for selecting data in one or more frequency bands.

19. The apparatus of claim 11 wherein said means for obtaining comprises means for obtaining motor current transient readings at a plurality of points per cycle of alternating current.

20. The apparatus of claim 19 wherein said plurality of said points comprises 512 or more points.

21. A method for detecting motor bearing defects, said method comprising:

obtaining motor current transient data during motor start-up;

detecting motor bearing faults by analyzing in a processor said motor current transient data obtained during motor start-up; and

determining using said processor deviations from baseline data representing motor current transient data obtained during start-up of a motor without bearing defects.

22. An apparatus for detecting motor bearing defects, said apparatus comprising:

a circuit monitor capturing motor current transient data during motor start-up; and

a processor mat receives said motor current transient data from said circuit monitor, said processor being programmed to detect motor bearing faults by analyzing said motor current transient data obtained during motor start-up for determining deviations from baseline data representing motor current transient data obtained during start-up of a motor without bearing defects.