Method and connector having conductive elastomeric material encircled by a continuous layer of insulation in intimate contact therewith

[57] ABSTRACT

An electrical connector comprising: an explosive charge and a plurality of radially movable electrically conducting jaws contained within an electrically conducting housing. The housing is completely encircled by and bonded to a continuous insulation layer which is impervious to moisture. The bared conductor ends of two lengths of high voltage electrical cable are inserted through the insulation layer, between the jaws and in engagement with electrical contact rivets protruding from the propellant charge. The conductor of one of the cable lengths is grounded to its outer shielding. The second length of cable is provided with a current source impressed between its conductor and cable shielding. As a result, an electrical path for the current source is provided through the contact rivets and through the propellant charge. The charge is thereby detonated to propel the jaws into radial engagement on the cable conductors and in mechanical and electrical contact with the housing. The insulation layer remains undisturbed and bonded to the housing. This advantageously allows detonation of the propellant charge without entry through the insulation layer, or, in the alternative, requiring a multiple piece insulation layer which must be assembled over the cable subsequent to termination.

Claims, 10 Drawing Figures

<img file="US3761602A_D0001.tif" />

126

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PATENTEDStP25l973

3.761,602

SHEET 2 OF 7

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PATENTED SEP25I973

3,761,602

SHEET 3 OF 7

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PATENTEDS£P25t8?3 3.761.602

SHEET U Of 7

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PATENTED SEF2 51973

SHEET 5 OF 7

3.761,602

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PAWEDW25WJ 3.761.602

SHEET 6 OF 7 /—-CONDUCTIVE ELASTOMERIC 20 14/8 MATERIAL

<img file="US3761602A_D0007.tif" />

PATENTED SEP251973 3.761.602

SHEET 7 OF 7

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3,761,602

METHOD AND CONNECTOR HAVING CONDUCTIVE ELASTOMERIC MATERIAL ENCIRCLED BY A CONTINUOUS LAYER OF INSULATION IN INTIMATE CONTACT THEREWITH

An electrical connector comprising: an explosive charge and a plurality of radially movable electrically conducting jaws contained within an electrically conducting housing. The housing is completely encircled by and bonded to a continuous insulation layer which is impervious to moisture. The bared conductor ends of two lengths of high voltage electrical cable are inserted through the insulation layer, between the jaws and in engagement with electrical contact rivets protruding from the propellant charge. The conductor of one of the cable lengths is grounded to its outer shielding. The second length of cable is provided with a current source impressed between its conductor and cable shielding. As a result, an electrical path for the current source is provided through the contact rivets and through the propellant charge. The charge is thereby detonated to propel the jaws into radial engagement on the cable conductors and in mechanical and electrical contact with the housing. The insulation layer remains undisturbed and bonded to the housing. This advantageously allows detonation of the propellant charge without entry through the insulation layer, or, in the alternative, requiring a multiple piece insulation layer which must be assembled over the cable subsequent to termination. According to the present invention, a wholly contained, one-piece environment sealed electrical connection may be effected without disturbing its electrical insulation or sealant properties or otherwise requiring assembly of a multiple piece insulation layer which characteristically has inherent leakage paths therethrough.

The present invention relates to an environment sealed electrical connector, and more particularly to an electrical connector which may terminate and join high voltage electrical cable without disturbing either the insulation or sealant properties of an encircling insulation and sealant layer which forms an integral part of the connector and which is unsectioned to eliminate a multiple piece insulation and sealant layer and the possibility of electrical leakage paths therethrough.

The connector of the present invention is well suited for high voltage termination for electrical distribution and transmission cables in underground and overhead corrosive environments. Whereas, the prior art is replete with techniques for terminating and joining high voltage cables, there has been a long existing need for a means and method of providing a sound electrical connection without the presence of current leakage paths tending to generate heat and subsequent failure of the connection. In the prior art, a typical connector for electrical distribution and transmission cables required the use of insulation in a plurality of parts which are assembled over an electrical connection, or alternatively a molded in place insulation over a completed termination. In a multiple piece or molded in place insulation, voltage and moisture seepage paths through the mating parts are often experienced. Also contaminants are entrapped during fabrication of the insulation. Accordingly, the sealing integrity of the electrical connection and the ability of the splice to provide the necessary voltage stress is jeopardized. As another disadvantage, the insulation layer is seldom in sufficient intimate contact with the current carrying parts of such an electrical connector, thereby allowing air pockets and contaminants to be entrapped between surfaces of mating insulation sections and resulting in possible paths for voltage leakage and breakdown. Additionally, entrapment of air between the insulation sections and current carrying parts of such a conductor may allow for overheating of the current carrying parts of the connection. Thus the prior art connectors possess the disadvantages of inconvenience in requiring separate tooling to make a compression electrical connection, the subsequent application of insulation often with a multiple number of parts, the possibility of contaminants or air entrapped, voltage breakdown or leakage which results in insufficient longitudinal voltage stress relief for the connector, and a need for elaborate internal shielding methods for the connector requiring considerable operator skill and attention. As a result, there has been a long existing need for an electrical connector according to the present invention which is wholly contained, of one-piece construction, which utilizes an unsectioned sealant layer bonded directly to the current carrying parts of the connector to eliminate entrapment of air and contaminants, and which need not be disturbed or entered in order to terminate the connector to cable conductors, and which eliminates the need for operator skill and elaborate connection procedures.

In the present invention, a high voltage electrical connector is advantageously provided with an electrical insulation and environment sealant material forming an integral bonded part of the connector. The connector and environment protection enclosure may be transported as a single self-contained unit, thereby eliminating the need for additional supplies, compression connector tools, and multiple insulation parts. The connector is initially located on a cable with the insulation and sealant material intimately sealably encircling the cable. When the connector according to the present invention is subsequently terminated to the electrical cable, the insulation and sealant layer is undisturbed and automatically provides a sealed enclosure to the completed electrical connection, thereby eliminating the need for post-connection procedures and operator skill in fabricating a sealed enclosure.

Accordingly, it is an object of the present invention to provide a high voltage electrical connector having an intimately associated insulation and sealant enclosure, which connector may be successfully terminated to an electrical cable without disturbing an insulation and sealant enclosure.

Another object of the present invention is to provide a method and apparatus for terminating high voltage electrical cable with an electrical connector which is terminated to the electrical cable conductors without a need for compression tooling, which has an insulation layer intimately bonded to the current conducting portions of the connector to eliminate entrapment of contaminants or air and to eliminate a plurality of insulation parts which must be assembled, and wherein the connector may be terminated to electrical cable conductors without disturbing or entering the insulation layer thereof.

Another object of the present invention is to provide a method for initially locating an electrical connector and an insulation and sealing enclosure sealably in an electrical cable, and subsequently electrically terminating the connector to the cable without disturbing the

3,761,602 ³ sealed relationship between the cable and the enclosure.

It is another object of the present invention to provide method and apparatus for terminating high voltage, high tension electrical cable with an electrical connector, and simultaneously sealing the electrical connection from a corrosive environment without requiring post-connection procedures, operator skill and the need for transporting a considerable amount of supplies and equipment.

Other objects and many attendant advantages of the present invention will become apparent upon perusal of the following detailed description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a fragmentary perspective of an electrical connector and an encircling insulation sealant layer as a self-contained unit according to a preferred embodiment of the present invention;

FIG. 2 is a fragmentary perspective of the preferred embodiment as shown in FIG. 1 with parts broken away and with parts in section to illustrate the internal details thereof;

FIG. 3 is an enlarged fragmentary perspective with parts in exploded configuration further illustrating the internal details of the preferred embodiment as shown in FIG. 2;

FIG. 4 is an enlarged perspective of portions of the preferred embodiment of FIG. 3 with parts broken away to illustrate the internal details thereof;

FIG. 5 is an enlarged fragmentary perspective of a portion of the preferred embodiment as shown in FIG. 2, further illustrating assembly procedures thereof;

FIG. 6 is an enlarged fragmentary elevation in section of a portion of the preferred embodiment shown in FIG. 2 and illustrating the internal details thereof;

FIG. 7 is an enlarged fragmentary perspective of a portion of the preferred embodiment as shown in FIG. 2 with parts in section further illustrating assembly of component parts thereof;

FIG. 8 is an enlarged fragmentary elevation in section of a portion of the preferred embodiment as shown in FIG. 2 and further illustrating the component parts of the preferred embodiment prior to termination to an electrical cable;

FIG. 9 is a section taken along the line 8—8 of FIG. 7; and

FIG. 10 is an enlarged fragmentary elevation in section of the preferred embodiment as shown in FIG. 7 with the component parts of the preferred embodiment in mechanical and electrical connection to an electrical cable.

With more particular reference to the drawings, there is shown in FIG. 1, generally at 1, an electrical connector according to the present invention. As more particularly shown in FIGS. 2,3, 4 and 6, the connector 1 includes a generally cylindrical, relatively massive electrically conducting chamber block 2 having an internal longitudinal bore 4. The block 2 includes a pair of tapered cylindrical, electrically conducting housing portions 6, 8, having corresponding encircling bead portions 10 fused together and electrically joining together the housing portions 6 and 8. As a result, a continuous electrically conducting housing is provided. The housing may also be of one-piece construction. The chamber block 2 is provided with an external annular groove 12 positioned radially of the bead portion 10 and receiving extruded portions of the housing members 6 and 8 thereby locking the housing portions 6 and 8 to the chamber block 2.

As shown in FIGS. 5 and 2, the housing portions 6 and 8 are enclosed within a molded seamless continuous layer of electrically conducting elastomeric material 14 having generally flared end portions 16 and 18 respectively bonded in intimate contact with, and encircling and covering, the terminal end portions 16' and 18' of the corresponding tapered cylindrical portions 6 and 8. Imbedded within the conducting layer 14 is a generally cylindrical sleeve of conducting material 20 having a reduced diameter medial portion 22 in contact with the beads 10. As shown in FIG. 5, the cylindrical ends of the sleeve 20 extend substantially into the flared terminal end portion 18 of the conducting layer 14, thereby assuring distribution of voltage from the tapered cylindrical conducting portions 6 and 8 throughout the entire mass of the conducting layer 14 and also providing a heat shield for the portions 6 and 8. The layer 14 is advantageously of a resilient conductive elastomeric material and is encircled by a substantially thick seamless continuous layer 22 of electrical insulation material bonded to and in intimate contact with the conducting layer 14 and having integral substantially elongated tapered cylindrical portions 24 and 26. As shown in FIGS. 2 and 5, the tapered portions 24 and 26, required for voltage stress relief, encircle and substantially cover the flared end portions 16 and 18 of the conducting layer 14. The layer portion 24 includes a generally central cylindrical opening 28 extending longitudinally therethrough and through the flared end portion 16 of the conducting layer 14. In addition, the opening 28 communicates with the interior of the tapered cylindrical conducting housing portion 6 through the end portion 16' thereof. In similar fashion, the tapered portion 26 of the insulation layer is provided therethrough with an elongated cylindrical opening 30 extending longitudinally therethrough and through the flared end portion 18 of the conducting layer 14. The opening 30 is in communication with the interior of the tapered cylindrical conducting housing portion 8 through the end portion 18' thereof. As shown in FIGS. 1, 2 and 5, the insulation layer 22 is provided thereover with a tough, relatively thin seamless continuous layer 32 of conducting material forming an outer moisture impervious jacket. As shown at 34, the insulation layer 22 is provided with a radially protruding external bead 34 interposed between adjacent spaced marginal margins 36 and 38 of the conducting layer 32 thus providing a shielding gap good for interrupting 1-2 KV charge across the connector exterior. Accordingly, the conducting layer 32 is discontinuous at the bead 34 wrapping and overlying the margin 36 and being disposed under the covering provided by the margin 38 of the insulating layer 32. As more particularly shown in FIGS. 5 and 6, the conducting jacket 32 is provided with a cylindrical end portion 40 encircling the terminal end of the tapered insulation layer portion 24. The end portion 40 has an integral radially projecting internal flange 42 overlying the terminal end of the tapered insulation layer portion 24. In a similar fashion, the outer jacket 32 has an integral, generally enlarged cylindrical end portion 44 encircling and covering the terminal end of the tapered cylindrical insulation layer portion 24. The portion 44 includes a radially projecting internal annular flange 46 covering the terminal

3,761,602 end of the tapered cylindrical insulation layer portion 26.

With reference to FIGS. 3, 5 and 7, assembly of the connector component parts will be described in detail. Thus as shown in FIG. 3, the connector includes a first generally cylindrical piston 48 slidably mounted within the bore 4 of the block 2. The piston 48 has a hollow interior 50 communicating with one end thereof and a flared head 52 at the other end thereof. The flared head 52 is provided with an opening 54 therethrough to receive an electrically conducting rivet 56 encircled by electrical insulation 58. As shown in FIGS. 4 and 8, the rivet 56 is provided with a flared head extending into the interior 50 of the piston 48 and a peened head protruding from the exterior of the piston head 52. The flared head 52 is provided thereover with an encircling collar 60 of insulation material. The collar includes a radially projecting annular inner flange 62 overlying the head 52 of the piston 48, with a washer 63 in turn overlying the flange 62. In the assembled condition, the collar 60 abuts against one cylindrical end of the block 2. As shown with reference to FIGS. 3, 5 and 7, a plurality of annularly spaced electrically conducting wedge segments 64 are provided each with a radially projecting segmented cylindrical lip 66 of flared configuration. As shown in FIG. 5, the segment 64 is individually grouped by a long tool 68 and inserted into the opening 26 in registration within the tapered cylindrical end portion of the collar 60. With all the wedge segments 64 in peripheral spaced relationship, as shown in FIG. 7, another long tool 70 grips a frangible ring 72 forcibly inserting it between the jaws 64 and retaining the lip portions 66 of the jaws against the annular collar 60. As shown in FIG. 3, each of the jaws 64 is also provided with an exterior strip of insulation material 74 adjacent the tapered end of each wedge segment 64 initially electrically insulating each wedge segment from the encircling conducting housing portion 6. The insulation 74 will be broken upon firing to enable electrical contact between the wedge segments and housing portion 6.

With reference to FIG. 4, there is generally shown at 76 a propellant charge having a quantity of propellant 78 within an encircling cylindrical casing 79 of insulation material. The charge 76 is further provided with end caps 80 and 82 of electrically conducting material. The end caps are interconnected by a heater wire 84 imbedded within the quantity of propellant 78. The charge 76 is inserted internally of the hollow interior 50 of the piston 48 with the end cap 80 in electrical contact with the rivet 56. A second piston 86 of cylindrical configuration and provided centrally therethrough with a conducting rivet 88 having a flared end 90 and a peened enlarged head 92. A cylindrical layer of insulation material 94 electrically isolates the rivet 88 from the encircling piston 86. The piston is provided at one end with an enlarged diameter head 96 of beveled configuration and received in an internally tapered generally cylindrical collar 98 of insulation material. The collar 98 includes an internal annular flange portion 100 overlying the end of the head 96. In practice, the piston 86 is inserted internally of the piston 48 with the protruding flared rivet head 90 in electrical engagement against the end cap 82 of the propellant charge 76. An annular seal 101 encircles the rivet head 90 and makes a pressure tight seal internally of the piston 48. The seal prevents gases generated upon firing from escaping and contaminating the contact areas of the connector. As shown in FIG. 3, a second plurality of wedge segments 64 having corresponding flared lip portions 66 and electrical insulation bands 74 are received on the collar 98 with the collar 100 of the insulation material collar 98 interposed between the wedge segments and the piston 86. A frangible ring 72 is inserted between the wedge segments 86 to retain the corresponding flared lip portions 66 into the tapered internal portion of the collar 98. Thus, in the completed assembly, the collar 98 abuts against the end portion of the chamber block 2, with the wedge segments 64 associated with the piston 86 disposed interiorly of the tapered cylindrical housing portion 8.

With reference to FIGS. 6 and 8, termination of the connector to an electrical cable will be described in detail. The end portion of the electrical cable is trimmed to expose a length of central conductor strands 102. In a typical cable, the strands 102 are encircled by a relatively thick layer of insulation material 104 which must be tapered at 106 adjacent the exposed strands 102 to allow insertion partially into the housing portions 6 or 8 for encircling and supporting the strands 102 to prevent their unraveling upon firing the propellant and making an electrical termination with the wedge segments, as explained below. The cable is initially trimmed as shown in FIG. 6 to expose a length 108 of semi-conducting screen or shielding layer encircling the insulation layer 104. Further trimming of the cable exposes a longitudinal length of spirally wrapped electrically conducting foil 110 which encircles the semiconductive screen or shielding 108. Typically in a high voltage cable capable of transmitting 69 KV the foil 110 is provided thereover with a plurality of conducting drain wires some of which are shown at 112. The drain wires carry ground currents and the foil establishes continuous shielding and prevents the drain wires from imbedding in the semi-conducting shielding. The drain wires and the metal foil 110 are encircled by an outer jacket 114 which forms a moisture impervious and environment sealing jacket covering for the cable. To assemble the connector and cable, the cable strands 102 are inserted between the corresponding plurality of jaws in abutment against a corresponding contact rivet head 59 or 92. The tapered portion 106 of the insulation material is received internally of the corresponding tapered cylindrical housing portion 6 or 8. The exposed longitudinal length of insulation material 104 is forcefit within a corresponding opening 28 or 30 of the elongated connector seamless insulation portions 24 or 26, thereby forming a void-free interference fit to eliminate the possibility of corona during operation of the transmission line. The insulation portions are resiliently radially outwardly compressed by the cable to insure a desired seal.

As shown in FIG. 6, the corresponding flange portions 42 or 46 of the connector outer jacket 32 encircles the insulation layer 104 of the cable to provide a voltage stress relief therefor. The semi-conducting screen 108 of the cable is received internally of the corresponding enlarged cylindrical portion 42 or 44 of the connector jacket 32. Each cylindrical portion 42 or 44 is provided thereover with an encircling jacket 116 of an elastomeric semi-conducting material which is also impervious to moisture. Each jacket includes an internal reduced diameter portion 118 intermediate an end 120 of the jacket 116 latchably receiving and encircling

3,761,602 a corresponding connector jacket portion 42 or 44, and providing seal at that point. Each jacket portion 116 includes an internal annular metal sleeve 122 immediately adjacent the reduced diameter portion 118. Each sleeve 122 is in intimate contact on the drain wires 112 and the wrapped foil 110 of the cable. This is accomplished by forcibly inserting the cable through the jacket 116, the sleeve 122 having a flared lip 124 providing a flared lead-in surface allowing forcible entry of the wires 112 and the foil 110 into the sleeve 122. As shown at 126 in FIG. 6, an electrical contact terminal is secured to the flared lip 124 and protrudes through an integral boss 128 of the jacket 116. The jacket 116 is provided with an end portion 130 which intimately encircles the outer jacket 114 of a corresponding cable. The jacket 116 accordingly provides an environment seal to prevent leakage of moisture along the cable and into the connector 1. In addition, the jacket sleeve 122 electrically connects to drain wires 112 and the foil 110 and provides an electrical contact 126 for grounding. Thus as shown in FIGS. 2, 6 and 8, each cable has its conductor strands 102 in contact with a corresponding contact rivet head 59 or 92. An electrical path is provided along the cable strands 102, through the contact rivets 56 and 88 and through the propellant charge 76 by virtue of the heater wire 84. Such electrical path is electrically insulated by the casing 79 encircling the propellant charge 76, the insulation 58 and 94 encircling the rivet 56 and 88, and the fact that the jaws 64 are radially spaced by their insulation strips 74 from the tapered cylindrical conducting housing portions 6 and 8. Each cable is accordingly positioned internally of the corresponding group of connector jaws and sealably contained within the insulation layer 22 of the connector and a jacket 116, as above-described.

The electrical connection may be accomplished by impressing a current through the heater wire 84 in the propellant charge 76, thereby detonating the propellant 78. As a feature of the present invention, this may be accomplished without entry into the connector or disturbing the sealant or insulation properties thereof. More specifically, this is accomplished by an operator temporarily providing a current path between the conductor strands 102 of one of the cable lengths and its shielding 110 at a location anywhere on said cable externally of the connector 1, and by temporarily providing a current path bridging between the terminals 126. Thus, upon impressing a current source between the conductor strands 102 of the other cable length at its shielding 110 at a location anywhere on said other cable length externally of the connector 1, a current path is provided, from one conductor to its shielding, across the terminals 126, through the other cable shielding 110 and its conductor. A return path is provided across the insulation encircled contact rivets 56 and 88, and through the other conductor 102 and its shielding 110. The heater wire 84 carries the current path between the contact rivets 56 and 88, thereby becoming heated upon passage of the current therethrough to ignite or otherwise detonate the propellant 78. As shown in FIG. 9, detonation of the propellant as illustrated forcibly displaces the pistons 48 and 86 outwardly away from one another, causing the corresponding groups of jaws 64 to be displaced forcibly toward the narrow ends of the corresponding tapered housing portions 6 and 8. The seal 101 prevents exhaust of the detonated propellant from internally of the piston 48 to insulation interfaces and the electrically conducting surfaces of the connector. The tapered configurations of the jaws allow them to become radially wedged between the conductor strands 102 and the corresponding tapered housing portions 6 and 8. The insulation 74 is broken to allow the tapered cylindrical outer periphery of each jaw 64 to matingly engage and intimately contact the tapered cylindrical configuration of a corresponding housing portion 6 or 8 to provide an electrical contact surface distributed over a relatively large surface area of the outer periphery of each jaw 64. Each group of jaws 64 is thereby radially compressed in intimate electrical an mechanical contact on the corresponding cable strands 102, which become mechanically as well as electrically connected by the jaws 64 to the housing portion 6 and 8. The mechanical connection is able to resist substantial tension loads on the cable strands 102, with an increase in tension of the strands 102 having a tendency to urge the corresponding groups of jaws 64 in contact therewith into tighter wedging contact between the strands 102 and the corresponding tapered housing portions 6 or 8. The described propelled displacement of the jaws 64 is accomplished within a relatively short span of time, allowing the jaws 64 to become radially wedged as described without overcoming the inertia of the cable and causing the cable to become displaced with respect to the connector 1. Accordingly, the jaws 64 radially engage the cable strands 102 and only slightly displace the cable. This movement is not sufficient to damage the seal which is distributed over a substantial length of the cable. The slight movement is used as an indicator that the wedge segments have been displaced sufficiently to make the electrical connection.

Although preferred embodiments of the present invention have been described and illustrated in detail, it should be understood that other embodiments and modifications of the present invention which would be obvious to one having ordinary skill in the art are intended to be covered by the spirit and scope of the appended claims, wherein: