Method and apparatus for determining electrical contact wear

• US 20040256551A1
• Filed: 07/22/2004
• Published: 12/23/2004
• Est. Priority Date: 12/13/2002
• Status: Active Grant

• Current Assignee: Nichols Applied Technology LLC
• Original Assignee: Nichols Applied Technology LLC
• Inventors: Nichols, Bruce W.
• Granted Patent: US 7,038,201 B2
• Time in Patent Office: Days
• US Class Current: 250/302
• CPC Class Codes: G01N 21/8422 Investigating thin films, e.g. matrix isolation method
• CPC Class Codes: H01H 1/0015 Means for testing or for inspecting contacts, e.g. wear indicator measuring circuits G01R31/3274
• CPC Class Codes: H01H 2001/0026 wherein one or both contacts contain embedded contact wear signal material, e.g. radioactive material being released as soon as the contact wear reaches the embedded layer
• CPC Class Codes: H01H 2001/0031 by analysing radiation emitted by arc or trace material

Abstract

A fluorescent trace material is provided within at least a portion of an electrical contact or interrupter assembly component, or a cavity defined therein. At least a portion of the fluorescent trace material is exposed or released from the electrical contact or interrupter assembly component, indicating a degree of component wear.

Claims

1. An electrical contact, comprising:

a fluorescent trace material, wherein at least a portion of the fluorescent trace material is released from the electrical contact as the contact experiences wear.

2. The electrical contact of claim 1, wherein the fluorescent trace material comprises a nanocrystal quantum dot material.

3. The electrical contact of claim 1, wherein the nanocrystal quantum dot material comprises CdSe/ZnS.

4. The electrical contact of claim 1, wherein the fluorescent trace material is dispersed within at least a portion of the electrical contact experiencing wear.

5. The electrical contact of claim 1, wherein the fluorescent trace material is contained in one or more portions of the electrical contact assembly experiencing wear.

6. The electrical contact of claim 5 wherein the fluorescent trace material is contained in one or more cavities formed by or secured within the electrical contact.

8. The electrical contact of claim 6, wherein the cavity is configured so that the fluorescent trace material is released from the cavity into a surrounding medium when the contact assembly has eroded to a detectable erosion point.

9. The electrical contact of claim 6, wherein the cavity is configured so that the fluorescent trace material is released from the cavity into a surrounding medium when the contact assembly has eroded sufficiently that an opening develops to the cavity.

10. The electrical contact of claim 6, wherein the fluorescent trace material is a nanocrystal quantum dot material.

12. The contact or contact assembly of claim 10, wherein the cavity is configured so that the fluorescent trace material is released from the cavity into a surrounding medium when the contact or contact tip has eroded to a detectable erosion point.

13. The contact or contact assembly of claim 10, wherein the fluorescent trace material consists of the elements chosen from the elements of periodic groups 11-VI, III-V or IV-VI and are nanocrystals ranging in size from 2 to 10 nanometers.

7. An electrical contact, comprising:

a cavity defined in or on the contact assembly; and

a fluorescent trace material within the cavity.

11. A contact assembly, comprising:

a conductive base;

a contact tip connected to the base or contact fabricated entirely of tungsten-based material; and

a cavity defined in the sacrificial contact, wherein the cavity contains a fluorescent trace material.

14. A device for detecting fluorescent trace material in a medium surrounding a contact assembly, comprising:

a source of electromagnetic radiation;

a detector for sensing the level of fluorescent radiation generated by the fluorescent trace material in response to the electromagnetic radiation source;

a means for transmitting electromagnetic radiation from the electromagnetic radiation source to the surrounding medium; and

a means for transmitting fluorescent radiation between the surrounding medium and the detector.

15. The detection device of claim 14, wherein the means for directing electromagnetic radiation from the electromagnetic radiation source to the surrounding medium and the means for transmitting fluorescent radiation between the surrounding medium and the detector comprise at least one optically-transmissive conduit.

16. The detection device of claim 15, further comprising a connector on the at least one optically-transmissive conduit configured to engage an access port in to an enclosure of the electrical contact assembly.

17. The detection device of claim 14, wherein the electromagnetic radiation source is an ultraviolet light emitting source.

18. The detection device of claim 14, wherein the electromagnetic radiation source emits electromagnetic radiation with a broad-band wave-length.

19. A device for detecting fluorescent trace material in a medium surrounding a contact assembly, comprising:

a source of electromagnetic radiation;

a detector for sensing the level of fluorescent radiation generated by the fluorescent trace material in response to the electromagnetic radiation source;

a first optical guide component for directing electromagnetic radiation from the electromagnetic radiation source to at least a portion of the surrounding medium; and

a second optical guide component for directing fluorescent radiation from the fluorescent trace material in the surrounding medium the detector.

20. The detection device of claim 19, wherein the electromagnetic radiation source is an ultraviolet light emitting source.

21. The detection device of claim 19, wherein the electromagnetic radiation source emits broad-band electromagnetic radiation with a wave-length of about 254 nm.

22. A method for determining erosion of a contact assembly, the method comprising:

providing a fluorescent trace material within the contact assembly;

allowing the contact assembly to be eroded until at least a portion of the fluorescent trace material is released into a surrounding medium; and

monitoring at least one point in the surrounding medium to detect a quantity of fluorescent trace material dispersed into the surrounding medium as an indicator of erosion of the contact assembly.

23. The method of claim 22, wherein the fluorescent trace material is provided within a cavity defined in the contact assembly.

24. The method of claim 22, wherein the monitoring step further comprises the steps of:

directing electromagnetic radiation into the surrounding medium; and

sensing the amount of radiation emitted by the fluorescent trace material to determine the amount of fluorescent trace material in the surrounding medium.

25. The method of claim 24, wherein the electromagnetic radiation is ultraviolet radiation.

26. The method of claim 24, wherein the electromagnetic radiation has a wave-length of about 254 nm.

27. The method of claim 24, wherein the ultraviolet radiation is generated from a source located within an enclosure surrounding the electrical contact assembly.

28. The method of claim 27, wherein the ultraviolet radiation is generated from a source located in a fluorescent trace material detecting device.

29. The method of claim 22, wherein the step of monitoring the surrounding medium comprises the steps of:

circulating the surrounding medium through a particulate concentration device;

directing electromagnetic radiation onto the fluorescent trace material in the particulate concentration device; and

detecting the level of fluorescent radiation emitted in response to the electromagnetic radiation.

30. The method of claim 29, wherein:

the particulate concentration device comprises a transparent or translucent observation wall; and

the electromagnetic radiation is directed through the observation wall to the fluorescent trace material.

31. A method for determining the presence of fluorescent material associated with wear of an electrical contact assembly, comprising the steps of:

generating electromagnetic radiation;

directing the electromagnetic radiation to fluorescent material indicating wear of the contact assembly;

detecting the amount of fluorescent radiation generated by the fluorescent material in response to the electromagnetic radiation; and

determining a level of wear of the electrical contact assembly form the amount of fluorescent radiation detected.

32. A method for determining the level of a fluorescent trace material present in a medium surrounding an electrical contact assembly, comprising the steps of:

circulating the surrounding medium through a particulate concentration device containing a collection surface;

directing electromagnetic radiation to the particulate concentration device; and

detecting the amount of fluorescent radiation generated by the fluorescent trace material collected by the particulate concentration device in response to the electromagnetic radiation.