Test probe

• US 20040070404A1
• Filed: 10/15/2002
• Published: 04/15/2004
• Est. Priority Date: 10/15/2002
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Shah, Manoj Ramprasad, Richter, Timothy Gerard, Lee, Sang-Bin, Kliman, Gerald Burt
• Granted Patent: US 6,847,224 B2
• Time in Patent Office: Days
• US Class Current: 324/545
• CPC Class Codes: G01R 1/067 Measuring probes
• CPC Class Codes: G01R 31/34 Testing dynamo-electric machines

Abstract

A probe includes at least one core and at least one sense coil associated with the core. The ends of the core are arranged in a contact-free, spaced relationship between opposed surfaces of adjacent lamination teeth of a stator. Air gaps are maintained between the ends of the probe core and the opposed surfaces. The total of the two air gaps is constant. The probe is supported on a carriage arrangement and moved along the teeth. Variations in leakage flux produced with the stator energized with an energization winding to produce a flux which is a few percent of is normal energization level, are monitored.

Claims

1. A probe for detecting abnormalities in an electrical device having a structure through which leakage flux passes, comprising:

a sense coil; and

a probe core disposed with the sense coil and configured so that first and second sensing end portions of the core are supported in a spaced contact-free relationship between opposed adjacent surfaces of portions of the electrical device to form first and second air gaps between the first and second sensing end portions of the core and the respective surfaces adjacent thereto.

2. A probe as set forth in claim 1, wherein a total of the first and second air gaps is constant.

3. A probe as set forth in claim 1, wherein the core comprises a material having high initial permeability and high resistivity characteristics.

4. A probe as set forth in claim 1, wherein the core comprises a plurality of laminated layers of a material and wherein the laminated layers have high initial permeability and high resistivity characteristics.

5. A probe as set forth in claim 1, wherein the electrical device is a stator core of an electrical generator/motor.

6. A probe as set forth in claim 5, wherein the stator core has a plurality of teeth which project inwardly into an interior of the stator core and wherein slot wedges are disposed between adjacent teeth.

7. A probe as set forth in claim 6, further comprising a probe support carriage which is adapted to roll along a slot wedge.

8. A probe as set forth in claim 1, further comprising a carriage which supports the probe so that the probe is adapted to move along a surface of the device and which maintains the probe in a position wherein the sensing end portions of the core are maintained in the spaced contact-free relationship between the opposed adjacent surfaces of the electrical device.

9. A probe as set forth in claim 8, wherein opposed sides of adjacent teeth are the opposed adjacent surfaces of the portions of the electrical device and wherein the carriage has guide members which are adapted to contact the opposed sides of the adjacent teeth.

10. A probe as set forth in claim 8, wherein the probe is mounted on an extension piece of the carriage which is adapted to be adjustable in length.

11. A probe as set forth in claim 1, wherein the probe is supported on a carriage arrangement adapted to pass over a surface of a wedge member which is disposed between the opposed adjacent surfaces.

12. A probe as set forth in claim 1, further comprising a circuit which is electrically connected with the sense coil and which is responsive to signal variations that are produced in response to the core being exposed to variations in leakage flux in the first and second air gaps.

13. A probe as set forth in claim 1, further comprising a winding which is disposed with the electrical device and an energization source which energizes the winding in a manner which induces a flux in the device that produces a leakage flux.

14. A probe as set forth in claim 13, wherein the energization source is adapted to energize the winding to a level whereat a flux, which is induced in the device, is a predetermined fraction of the flux which is induced in the device during normal operation thereof.

15. A probe as set forth in claim 1, wherein the probe is adapted to move in a predetermined spaced, relationship over a surface of a member disposed between the adjacent projections.

16. A method of detecting faults in an electrical device comprising the steps of:

supporting a probe, having a solid core and a coil disposed with the core, so that sensing portions of the core are maintained in a contact-free, spaced relationship between adjacent surfaces of members which form part of the device and through which leakage flux passes;

inducing energization of the device to a predetermined level which is lower than a normal operating level and thus produce leakage flux;

detecting a leakage flux which occurs between the opposed surfaces using the probe;

moving the probe to a new position with respect to the opposed surfaces and detecting a leakage flux at the new position; and

monitoring the fluctuation in probe output and detecting a fault in response to the detection of an abnormal leakage flux.

17. A method as set forth in claim 16, wherein the step of energization is carried out by disposing an energization winding about a predetermined portion of the electrical device and inducing a flux in a circuit defined by a structure of the device.

18. A method as set forth in claim 16, wherein the step of moving the probe is carried out by supporting the probe on a carriage and moving the probe to the new position by moving the carriage along a surface forming part of the device.

19. A method as set forth in claim 16, wherein the step of moving comprises the step of guiding the probe along in the predetermined spaced relationship with a member which is rigidly connected to, and which extends between, the opposed surfaces.

20. An apparatus for detecting faults in an electrical device comprising:

means for supporting a probe, which has a solid core and a coil disposed with the core, so that sensing end portions of the core are maintained in a contact-free, spaced relationship between opposed surfaces of members which form part of the device and through which leakage flux passes;

means for inducing energization of the device to a predetermined level which is lower than a normal operating level;

means responsive to the probe for detecting a leakage flux which occurs between the opposed surfaces;

means for moving the probe to a new location with respect to the opposed surfaces and detecting leakage flux at the new location; and

means for monitoring the fluctuation in probe output and determining a presence and location of a fault in response to the detection of an abnormal leakage flux fluctuation.

21. An apparatus as set forth in claim 20, wherein the energization means comprises a winding disposed about a predetermined portion of the electrical device for inducing a flux in a circuit defined by a structure of the device.

22. An apparatus as set forth in claim 20, wherein the means for moving the probe comprises a carriage on which the probe is suspended, the carriage being adapted to move the probe to the new position by moving along a surface forming part of the device.

23. An apparatus for detecting faults in an electrical device comprising:

a single probe having a core of a material having high initial permeability and high resistivity characteristics, and a coil disposed with the core, the probe being adapted to be supported so that all sensing portions of the core are maintained in a contact-free spaced relationship between predetermined opposed surfaces of the electrical device and so that the sensing portions of the core are exposed to leakage flux which is produced by the electrical device and which passes between the opposed surfaces and through air gaps defined between the opposed surfaces and the sensing portions of the core;

an excitation winding removably disposed with the electrical device and operatively connected with a source of excitation voltage for inducing a flux in an electrical circuit in the electrical device; and

a data acquisition system operatively connected with the excitation winding and the sensor coil for monitoring the output of the sensor and detecting faults in the electrical device which cause change in the leakage flux.

24. An apparatus as set forth in claim 23, further comprising a probe support carriage, the carriage being operatively connected with the probe and adapted to support the probe so that the sensing portions of the core are maintained in the contact-free spaced relationship between the predetermined surfaces of the electrical device and so that the probe is moved through the electrical device to scan the electrical device for faults which produce a change in leakage flux.