Electrical contact wear and temperature indicator

• US 6,188,035 B1
• Filed: 01/10/2000
• Issued: 02/13/2001
• Est. Priority Date: 09/10/1996
• Status: Expired due to Fees

• Current Assignee: Nichols Applied Technology LLC
• Original Assignee: Bruce W. Nichols
• Inventors: Nichols, Bruce W.
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US09/480,078
• Time in Patent Office: 400 Days
• Field of Search: 200/11.B, 200/11.C, 200/11.TC, 200/15, 200/61.4, 200/254, 200/262-270, 200/312, 218/1, 218/43, 218/53, 218/57-67, 218/68, 218/72, 218/74, 218/90-117, 218/146, 324/415-424, 340/635, 340/638, 340/644, 340/654, 73/290.2
• US Class Current: 218/91
• 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 2009/0061 Monitoring tap change switching devices

Abstract

The design of electrical switches that operate under load (with current flowing) requires replacement of the electrical contact after erosion and wear experienced by arcing and raised temperatures reduce functionality below acceptable limits.

A quantity of trace element or compound is implanted at a depth representative of the point at which wear or erosion requires contact replacement. When exposed by wear or erosion, the quantity of the trace element is released into the oil or other medium surrounding the contact, providing an indication of excessive wear.

Claims

1. A method for determining when replacement is required of an electrical contact assembly operating within an oil environment and having at least one element configured for experiencing wear, said element being mounted to a conductive base, the method comprising:

defining a cavity within the at least one element configured for experiencing wear;

providing a trace element within said at least one cavity;

allowing said at least one element configured for experiencing wear to be eroded until an opening is formed in said at least one element configured for experiencing wear;

permitting said trace element to disperse from said cavity through said opening into said oil environment; and

monitoring said oil environment to determine when a sufficient quantity of trace element has dispersed into the oil environment to indicate that said electrical contact assembly requires replacement.

2. The method of claim 1 wherein the step of monitoring further comprises using dissolved gas analysis (DGA) to identify when a sufficient quantity of trace element has dispersed into said oil environment to indicate that said electrical contact assembly requires replacement.

3. The method of claim 1 wherein the step of monitoring further comprises using infrared monitoring to identify when a sufficient quantity of trace element has dispersed into said oil environment to indicate that said electrical contact assembly requires replacement.

4. The method of claim 1 wherein said trace element comprises magnesium sulfate.

5. The method of claim 1 wherein the at least one element configured for experiencing wear comprises a material resistant to erosion from arcing.

6. The method of claim 1 wherein the at least one element configured for experiencing wear comprises a tungsten-based material resistant to erosion from arcing.

7. An electrical contact assembly operable within an oil environment, comprising:

a conductive base;

at least one element configured for experiencing wear, said element being mounted to and operatively connected to the base; and

means for indicating when said at least one element configured for experiencing wear has eroded to a predetermined erosion point.

8. The electrical contact assembly of claim 7, wherein said at least one element configured for experiencing wear defines at least one cavity, and further comprises a trace element contained within said at least one cavity.

9. The electrical contact assembly of claim 8 wherein said trace element comprises magnesium sulfate.

10. The electrical contact assembly of claim 8, wherein said means for indicating when said at least one element configured for experiencing wear has eroded to said predetermined erosion point comprises defining the formation of an opening in said at least one cavity through which opening said trace element may be dispersed.

11. The electrical contact assembly of claim 10 wherein said trace element comprises magnesium sulfate.

12. The electrical contact assembly of claim 7 wherein the at least one element configured for experiencing wear comprises a material resistant to erosion from arcing.

13. The electrical contact assembly of claim 7 wherein the at least one element configured for experiencing wear comprises a tungsten-based material resistant to erosion from arcing.

14. An assembly operable within an oil environment, comprising:

a conductive base;

at least one element configured for experiencing wear, said element being bonded to said base; and

means for indicating when said at least one element configured for experiencing wear has eroded to a predetermined erosion point.

15. The assembly of claim 14, wherein said at least one element configured for experiencing wear defines at least one cavity, and further comprises a trace element contained within said at least one cavity.

16. The assembly of claim 15 wherein said trace element comprises magnesium sulfate.

17. The assembly of claim 15, wherein said means for indicating when said at least one element configured for experiencing wear has eroded to said predetermined erosion point comprises defining the formation of an opening in said at least one cavity through which opening said trace element may be dispersed.

18. The assembly of claim 17 wherein said trace element comprises magnesium sulfate.

19. The assembly of claim 14 wherein the at least one element configured for experiencing wear comprises a tungsten-based material resistant to erosion from arcing.

20. The assembly of claim 14 wherein the at least one element configured for experiencing wear comprises a material resistant to erosion from arcing.