HIGH VOLTAGE FUSE ENCLOSURE

• US 3,818,407 A
• Filed: 09/25/1972
• Issued: 06/18/1974
• Est. Priority Date: 09/25/1972
• Status: Expired due to Term

• Current Assignee: Nelson W. Edgerton
• Original Assignee: Nelson W. Edgerton
• Inventors: Edgerton, Nelson W.
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Bell, Fred E.
• Application Number:
  US05/292,219
• Time in Patent Office: 631 Days
• Field of Search: 337/199,202,222,224 174/5,6,50 338/127,64
• US Class Current: 337/199
• CPC Class Codes: H01H 2085/0225 Means for preventing discharge, e.g. corona ring
• CPC Class Codes: H01H 85/56 the intermediate or auxiliary part having side contacts for plugging into the base, e.g. bridge-carrier type

Abstract

A corona-preventing shielding system for use with a high voltage fuse, the system including first and second conductive shield members, each extending longitudinally from adjacent one end of the fuse toward the other and terminating short of the other end of the fuse at longitudinally juxtaposed, and preferably overlapping, portions which are spaced apart but in close enough proximity such that the shield members envelop the fuse to establish an effective corona-preventing shield, but do not contact one another to provide an alternate electrical circuit between the fuse terminals.

Claims

1. A corona-preventing shielding system for a high voltage fuse having longitudinally opposed ends and a terMinal adjacent each end, said system comprising:

first conductive shield means for being electrically connected to one terminal of the fuse and enveloping one end of the fuse such that said first shield means extends longitudinally in the direction toward the other end of the fuse;

second conductive shield means for being electrically connected to the other terminal of the fuse and enveloping the other end of the fuse such that said second shield means extends in the direction toward the first shield means;

with each said conductive shield means terminating intermediate said one and said other fuse terminal, respectively, the terminating portions of each said conductive shield means being longitudinally juxtaposed in close enough longitudinal proximity with respect to each other to establish an effective coronapreventing shielding envelope about said fuse and to prevent the formation of an electrical field stress concentration between the terminating portions of each said conductive shield means, and being transversely spaced from one another such that the shielding envelope does not provide an alternate electrical circuit between the fuse terminals.

2. The invention of claim 1 wherein a member of high dielectric strength material is interposed between the transversely spaced terminating portions of the first and second conductive shield means.

3. The invention of claim 3 wherein:

said member of high dielectric strength material is a tube having interior and exterior surfaces; and

said first and second shield means respectively include generally tubular portions, one of said tubular portions extending along and being contiguous with the exterior surface of said tube and the other of said tubular portions extending along and being contiguous with the interior surface of said tube.

4. The invention of claim 3 wherein at least said other of the tubular portions is in intimate contact with the interior surface of said tube.

5. The invention of claim 4 wherein said tubular portions are comprised of conductive elastomeric material.

6. The invention of claim 4 wherein the tube has a length great enough to extend longitudinally from adjacent one end of the fuse to adjacent the other end of the fuse.

7. The invention of claim 3 wherein the respective transversely spaced terminating portions of said first and second layers of conductive material axially overlap one another.

8. The invention of claim 1 wherein the respective terminating portions of said transversely spaced first and second conductive shield means lie in a common transverse plane substantially perpendicular to the longitudinal extent of said fuse.

9. The invention of claim 1 wherein the respective terminating portions of said transversely spaced first and second conductive shield means longtudinally overlap one another.

10. The invention of claim 1 wherein the terminating portion of said second conductive shield means is located further from the central longitudinal axis of said fuse than the terminating portion of said first conductive shield means, and the terminating portions of said first and second conductive shield means are both located closer to said one terminal of said fuse than to said other terminal of said fuse.

11. The invention of claim 1 wherein the respective terminating portions of said first and second layers of conductive material lie in a common transverse plane substantially perpendicular to the longitudinal extent of said fuse.

12. A high voltage fuse enclosure for a fuse having opposed ends and a terminal adjacent each end, said enclosure comprising:

a housing having a wall, at least a portion of which is of insulating material, said wall including a generally tubular, axially extending portion and further portions for closing the tubular portions to establish a sealed chamber within which the fuse is to be enveloped;

a first contact member in said housing for engaging one terminal of the fuse;

a second contact member In said housing for engaging the other terminal of the fuse;

a first layer of conductive material electrically connected to the first contact member and extending along the wall toward the second contact member, said first layer terminating intermediate said first and second contact members;

a second layer of conductive material electrically connected to the second contact member and extending along the wall toward the first layer of said second layer terminating intermediate said first and second contact members;

the terminating portions of said first and second layers being axially juxtaposed with one another in such close axial proximity that the first and second layers establish a corona-preventing envelope within said wall, said envelope being effective to surround said chamber and prevent the formation of an electrical stress concentration between said terminating portions, said terminating portions of said first and second layers being transversely spaced from one another to prevent the completion of an alternate electrical circuit between the first and second contact members.

13. The invention of claim 12 wherein said first and second layers are generally tubular for extending along the wall toward the second and first contacts, respectively.

14. The invention of claim 12 wherein the transverse spacing between the terminating portions of the first and second layers is relatively small and a barrier of high dielectric strength material is interposed between the terminating portions.

15. The invention of claim 14 wherein the barrier of high dielectric strength material is a tube received within said housing in juxtaposed relation to said generally tubular, axially extending portion of said wall, said tube extending axially beyond the terminating portions toward each contact member to further isolate the first and second layers from one another.

16. The invention of claim 15 wherein the housing wall insulating material includes an elastomeric material, said first layer being a conductive elastomeric material integral with the insulating elastomeric material of said wall and extending along the exterior of said tube in intimate contact therewith, and said second layer extends along the interior of said tube in intimate contact therewith.

17. The invention of claim 14 wherein the housing wall insulating material includes said barrier of high dielectric strength material to further isolate the first and second layers from one another.

18. The invention of claim 14 wherein the barrier of high dielectric strength material is a tube having a wall with interior and exterior surfaces and first and second ends and extending essentially along the entire length of the chamber;

said terminating portion of the first layer extends along the exterior surface of the tube from the first end of the tube toward the second layer, which terminating portion of said first layer terminates short of the second end of the tube;

said terminating portion of the second layer extends along the interior surface of the tube from the second end of the tube toward the terminating portion of the first layer, which terminating portion of said second layer terminates short of the first end of the tube.

19. The invention of claim 18 in which the terminating portion of the first layer is axially located closer to the second end of the tube than the terminating portion of the second layer so that said terminating portions axially overlap and are spaced radially apart by the wall thickness of the tube.

20. The invention of claim 19 wherein the axially overlapping terminating portions of said first and second layer are both located nearer to the second end of said tube than to the first end of said tube.

21. The invention of claim 12 wherein the housing wall insulating material includes an elastomeric material and the first layer is a conductive elastomeric material integral with the insulating elastomeric material of the tubular portion of the housing waLl.

22. The invention of claim 12 wherein said first and second layers are comprised of conductive elastomeric materials.

23. The invention of claim 12 wherein the first and second layers are integral with the tube of high dielectric strength material.

24. The invention of claim 12 wherein the housing comprises:

a tubular part, at least a portion of which is comprised of elastomeric material;

at least one end part, at least a portion of which is comprised of elastomeric material, engageable with one end of the tubular part; and

complementary plug and receptacle means on said elastomeric portions of the tubular and end parts, said means having relative dimensions for engaging the end part with the tubular part in watertight relationship to seal the chamber and protectively encase the fuse.

25. The invention of claim 12 wherein the terminating portion of the second layer of conductive material is located further from the central axis of said fuse than the terminating portion of said first layer, and the terminating portions of said first and second layers of conductive material are both located closer to said first contact member than to said second contact member.

26. A high voltage fuse enclosure for a fuse having opposed ends and a terminal adjacent each end, said enclosure comprising:

a housing including a first part including a generally tubular, axially extending portion of insulating elastomeric material; and

at least one second part at least a portion of which is insulating elastomeric material, engageable with the first part to establish a sealed chamber within which the fuse is to be enveloped;

a first contact in said first part for engaging one terminal of the fuse;

a second contact in said second part for engaging the other terminal of the fuse;

a tube having a wall of high dielectric strength material extending axially along the chamber in intimate contact with the tubular portion of the first part;

a first layer of conductive material electrically connected to said first contact and having at least a portion extending along the exterior surface of the tube wall from one end of the tube toward the other end of the tube and terminating short of said other end;

a second layer of conductive material electrically connected to said second contact and having at least a portion extending along the interior surface of the tube wall from said other end toward said one end thereof and terminating short of said one end; and

said first and second layers being axially juxtaposed in close axial proximity and radially spaced apart by the wall thickness of the tube of high dielectric strength material such that the first and second layers establish a corona-preventing shield around said chamber without completing an alternate electrical circuit between the first and second contacts.

27. The invention of claim 26 wherein the first layer is comprised of a conductive elastomeric material integral with the insulating elastomeric material of the tubular portion of the first part.

28. The invention of claim 26 wherein the first and second layers are comprised of conductive elastomeric materials.

29. The invention of claim 26 wherein the first and second layers are integral with the tube of high dielectric strength material.

30. The invention of claim 26 wherein the terminal ends of both the first and second layer are located closer to said other end of the tube than to said one end of the tube.

31. The invention of claim 26 wherein the tube of high dielectric strength material extends axially from adjacent the first contact to adjacent the second contact.

32. The invention of claim 26 including complementary plug and receptacle means on the elastomeric portions of the first and second parts, said means having relative dimensions for engaging the second part with the first part in watertight relationship to seal the chamber and protectively encase the fuse.

33. The invention of claim 26 wherein the Respective terminating portions of said radially spaced apart first and second layers of conductive material lie in a common transverse plane substantially perpendicular to the longitudinal extent of said fuse.

34. The invention of claim 26 wherein the respective terminating portions of said radially spaced apart first and second layers of conductive material axially overlap one another.