Electric generator inspection system

• US 4,970,890 A
• Filed: 05/17/1989
• Issued: 11/20/1990
• Est. Priority Date: 11/23/1988
• Status: Expired due to Term

• Current Assignee: Siemens Power Generation, Inc.
• Original Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Inventors: Dailey, George F., Rethage, Wilbert B., Guenther, Paul, Pompa, Gerard A., Jaafar, Hamedo A., Katzor, Karl A.
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US07/353,306
• Time in Patent Office: 552 Days
• Field of Search: 73/865.8, 73/12, 73/572, 73/12, 358/100, 358/106, 358/107, 358/108, 324/158 MG, 324/551, 324/545
• US Class Current: 73/12.09
• CPC Class Codes: G01R 31/34 Testing dynamo-electric machines

Abstract

An inspection system inspects the interior of the stator of an electric generator for the existence of several problems. The inspection apparatus is mounted on a carriage that travels along the slots defined by the stator. An indexer is mounted to the rotor of the generator and can travel around the circumference of the rotor to deliver the carriage to the desired slot. An indexer plate is mounted to the indexer and can be registered with the desired slot to insure that the carriage can enter the slot from the indexer. An associated motor controller disables the motor if an electrical fault is disclosed.

Claims

1. An inspection system for an electric generator comprising:

apparatus for inspecting and providing information pertaining to the tightness of the stator coil wedges of the generator including impactor means for striking the coil wedges of the generator thereby generating an acoustical signal responsive thereto and electrical means for recording and analyzing the frequency of the acoustical signal and for computing an adjusted average of the frequency of more than one said acoustical signal which is inversely proportional to the tightness of said wedge;

means for delivering said apparatus to the site of inspection, and for retrieving said apparatus therefrom; and

means for causing said apparatus to conduct an inspection at an inspection site.

2. The system of claim 1 wherein said electrical means further comprises conditioner means arranged to receive said acoustical signal for buffering and differentiating thereby producing a differentiated signal.

3. The system of claim 2 wherein said conditioner means further comprises a zero-cross detector for receiving said differentiated signal and for producing a plurality of pulses one for each time interval said differentiated signal has a zero slope whereby the time between said pulses is representative of the tightness of said wedge.

4. The system of claim 3 wherein said impactor means comprises a solenoid for impacting a face of said wedge thereby generating said acoustical signal.

5. The system of claim 4 wherein said electrical means comprises an acoustic sensor for receiving said acoustical signal.

6. The system of claim 5 wherein said acoustic sensor is a microphone for detecting said acoustical signal.

7. The system of claim 6 wherein said means for delivering said apparatus to the site of inspection, and for retrieving said apparatus therefrom includes carriage means.

8. An inspection system for an electric generator comprising:

a carriage adapted to travel along the slots defined by the stator of the generator;

electrical means mounted on said carriage for inspecting and providing information pertaining to the tightness of the stator coil wedges of the generator;

means for moving said carriage along the stator slots to sites of inspection;

an indexer adapted to be releasably secured to the rotor of the generator, said carriage and said indexer being adapted to permit said carriage to be received and retained by said indexer when said carriage exits a slot;

means for aligning said indexer with each slot to permit said carriage to enter the slot when said carriage travels out of retention of said indexer;

means for moving the indexer around the circumference of the rotor to deliver said carriage to a desired slot; and

means for causing said electrical means to conduct an inspection at an inspection site.

9. The system of claim 8 wherein said electrical means for inspecting and providing information pertaining to the tightness of the coil wedges of the generator includes impactor means for striking the coil wedges of the generator and generating an acoustical signal responsive thereto.

10. The system of claim 9 wherein said electrical means for inspecting and providing information pertaining to the tightness of the coil wedges of the generator includes means for recording and analyzing the acoustical signal generated by said impactor means.

11. The system of claim 10 wherein said electrical means comprises an acoustic sensor for receiving said acoustical signal.

12. The system of claim 11 wherein said electrical means further comprises means for computing an adjusted average of the frequency of more than one acoustical signal which is inversely proportional to the tightness of said wedge.

13. The system of claim 12 wherein said electrical means further comprises conditioner means arranged to receive said acoustical signal for buffering and differentiating thereby producing a differentiated signal.

14. The system of claim 13 wherein said conditioner means further comprises a zero-cross detector for receiving said differentiated signal and for producing a plurality of pulses one for each time interval said differentiated signal has a zero slope whereby the time between said pulses is representative of the tightness of said wedge.

15. The system of claim 14 wherein said impactor means comprises a solenoid for impacting a face of said wedge thereby generating said acoustical signal.

16. The system of claim 15 wherein said acoustic sensor is a microphone for detecting said acoustical signal.

17. A system for inspection and providing information pertaining to the tightness of the stator coil wedges of an electrical generator comprising:

impactor means for striking the coil wedges and generating an acoustical signal responsive thereto;

an acoustic sensor arranged near said coil wedges for receiving said acoustical signal; and

electrical means associated with said acoustic sensor for recording, analyzing, and computing an adjusted average of the frequencies of more than one acoustical signal generated by said impactor means which average is inversely proportional to the tightness of said wedges.

18. The system of claim 17 wherein said electrical means further comprises conditioner means arranged to receive said acoustical signal for buffering and differentiating thereby producing a differentiated signal.

19. The system of claim 18 wherein said conditioner means further comprises a zero-cross detector for receiving said differentiated signal and for producing a plurality of pulses one for each time interval said differentiated signal has a zero slope whereby the time between said pulses is representative of the tightness of said wedge.

20. The system of claim 19 wherein said impactor means comprises a solenoid for impacting a face of said wedge thereby generating said acoustical signal.

21. The system of claim 20 wherein said acoustic sensor is a microphone for detecting said acoustical signal.