Surge arrestor apparatus and method

• US 5,023,745 A
• Filed: 09/06/1989
• Issued: 06/11/1991
• Est. Priority Date: 09/06/1989
• Status: Expired due to Term

• Current Assignee: ERICO International Corporation (nVent Electric Plc)
• Original Assignee: ERICO International Corporation (nVent Electric Plc)
• Inventors: Glass, John C.
• Primary Examiner(s): DEBOER, TODD
• Application Number:
  US07/403,366
• Time in Patent Office: 643 Days
• Field of Search: 361/56, 361/58, 361/91, 361/107, 361/111, 361/117, 361/120, 361/126, 361/127, 361/128, 361/331, 361/335
• US Class Current: 361/56
• CPC Class Codes: H02H 9/044 Physical layout, materials not provided for elsewhere varistors H01C7/12; spark-gaps H01T; Ovshinsky devices H10N70/00

Abstract

Surge arrestor assemblies for railroad and like circuits utilize a high surface area to cross-sectional area, broadband equal potential grounding plane which is in the form of a loop. Surges are electrically coupled to the broadband equipotential grounding plane through surge arrestors. The assembly ensures that each arrestor "see'"'"'s" the same impedance so that the voltage seen at the equipment is controlled. The grounding member is supported in recesses in mounting blocks which maintain its planar condition, and which also facilitate the connections to ground, lines, arresters and equipment.

Claims

1. A device for grounding an electrical surge in a circuit used in a railroad application, comprising:

a grounding member having a high surface to cross-sectional area ratio for facilitating the low impedance conductance of high frequency electrical energy;

a plurality of conductors for the conductance of electrical signals from a power source to a load; and

,

a plurality of surge arrestors electrically connected to said conductors and said grounding member for grounding any of such electrical signals to said grounding member when any of such signals exceeds a predetermined voltage.

2. A device as set forth in claim 1, wherein said grounding member is continuously conductive between all surge arrestors mounted thereon.

3. A device as set forth in claim 2, wherein said grounding member is flat.

4. A device as set forth in claim 3, wherein said flat grounding member is in the form of a rectangle.

5. A device as set forth in claim 4, wherein said grounding member is copper.

6. A device as set forth in claim 5, wherein said flat grounding member has a width to thickness ratio of approximately 30 to 1.

7. A device as set forth in claim 2, wherein said grounding member is tubular.

8. A device for grounding surges of electrical energy in circuits used in a railroad application, comprising:

a continuous conductive loop having a substantially equal impedance to ground at all points on the loop

a plurality of conductors for the conductance of electrical signals from at least one power source to a plurality of loads; and

,

a plurality of surge arrestors electrically connected to said conductors and said continuous conductive loop for grounding any of such electrical signals to said loop when any of such signals exceeds a predetermined voltage.

9. A device as set forth in claim 8, wherein said continuous conductive loop is in the form of a rectangle.

10. A device as set forth in claim 9, said continuous conductive loop having a high surface to cross-sectional area ratio for facilitating the low impedance conductance of high frequency electrical energy.

11. A device as set forth in claim 10, wherein said continuous conductive loop has long sides sufficiently short to facilitate low impedance conductance of high frequency electrical energy below the resonant frequency of the side.

12. A method of grounding a surge of electrical energy in railroad circuits, comprising the steps of:

tapping such electrical signal conducted through a circuit;

electrically coupling such electrical signal to a grounding path when the potential difference between such electrical signal and ground exceeds a predetermined voltage; and

,

conducting such electrical signal to ground along a grounding path having a high surface to cross-sectional area ratio for facilitating the low impedance conductance of high frequency electrical energy.

13. A method as set forth in claim 12, wherein said step of conducting includes conducting such electrical signal along a grounding path in the form of a loop.

14. A mounting block assembly for conductive elements in a railroad circuit surge arrestor sub-assembly, comprising:

a plurality of highly insulative mounting blocks, each including a top surface having a flat recess for orienting a flat grounding member therein, a bottom surface having a cavity for containing conductive elements, and a plurality of additional recesses located in such top and bottom surfaces maintaining a sufficient air gap between conductive elements mounted therein to prevent electrical discharge between such elements.

15. A mounting block assembly as set forth in claim 14, wherein said mounting blocks are constructed of a resin.

16. A mounting block assembly as set forth in 15 wherein said flat recess is the same depth as the thickness of said flat grounding member.

17. A mounting block assembly as set forth in claim 16 including a threaded insert in said block flush with the top of said flat recess to facilitate electrical connection to said grounding member.

18. A mounting block assembly as set forth claim 17 including two threaded inserts in said block flush with the top of said flat recess to either or both of which such electrical connection can be made.

19. In electrical circuits, a low impedance equipotential grounding plane supported in a recess in a plurality of mounting blocks with a surface exposed for mounting surge arrestors thereto each at a fixed distance with respect to said equipotential plane.

20. A device as set forth in claim 19 wherein said plane is recessed in each mounting block.

21. A device as set forth in claim 20 including a threaded insert in said mounting block to facilitate the connection of a surge arrestor to said plane.

22. A device as set forth in claim 20 wherein said plane is flat.

23. A device as set forth in claim 20 wherein said plane has a high surface to cross sectional area ratio.

24. A device as set forth in claim 20 wherein said plane is tubular.

25. A device as set forth in claim 20 wherein said plane is Litz wire.