US3317654A

US3317654A - Electrical cable terminal

Info

Publication number: US3317654A
Application number: US418678A
Authority: US
Inventors: Edward H Yonkers
Original assignee: Joslyn Manufacturing and Supply Co
Current assignee: Joslyn Manufacturing and Supply Co
Priority date: 1964-12-16
Filing date: 1964-12-16
Publication date: 1967-05-02
Anticipated expiration: 1984-05-02

Description

May 2, 1967 E. H. YONKERS ELECTRICAL CABLE TERMINAL 4 Sheets-Sheet l Filed Dec. 16, 1964 a Figli/lili iIllia! ,lll

May 2, 1967 E. H, YoNKERs 3,317,654

ELECTRICAL CABLE TERMINAL Filed Dec. 16, 1964 4 Sheets-Sheet 2 May 2, 1967 E. H. YoNKERs ELECTRICAL CABLE TERMINAL 4 Sheets-Sheet 3 Filed Deo. 16, 1964 @www May 2 1957 E. H: YONKERS 3,317,654

ELECTR ICAL CABLE TERMI NAL Filed Dec. 16, 1964 4 sheets-sheet 4 United States Patent O 3,317,654 ELECTRICAL CABLE TERMINAL Edward H. Yonkers, Glencoe, Ill., assignor to :loslyn Mfg. and Supply Co., Chicago, Ill., a corporation of Illinois Filed Dec. 16, 1964, Ser. No. 418,678 17 Claims. (Cl. 174-73) The present invention relates to electrical cable terminals and more particularly to terminals utilized with high voltage supply cables of the type including a central conductor surrounded by a concentric insulating cover and a concentric ground sheath surrounding the insulating cover.

Cable terminating devices of this type are disclosed and illustrated in the co-pending U.S. patent application Ser. No. 142,562, filed Oct. 3, 19611, which application is assigned to the same assignee as the present invention, and the present application constitutes an improvement on said co-pending application. These types of cable terminating devices include a rigid housing of insulating material, such as porcelain, having a terminal at one end of the housing and a grounding clamp adjacent the other end for supporting the structure on a terminal board or the like. The rigid housing is formed to define an elongated cavity adapted to receive an end portion of the cable and an elongated tubular dielectric elastic filler surrounds the end portion of the cable and is inserted into the cavity of the rigid housing. A conductive end fitting encloses the lower portion of the filler and the fitting is bolted to the grounding clamp on the rigid housing so that the fitting can be drawn upwardly to apply an end force to the filler to force it into the cavity.

One of the problems associated with these types of devices is the problem of providing an electrical connection of low resistance and high current capacity between the cable sheath and the end tting.

Accordingly, it is an object of the present invention to provide a new and improved electrical terminating device of the type described.

It is another object of the present invention to provide a new and improved terminal device of the type described which eliminates the above-mentioned problem.

Yet another object of the present invention is the provision of a new and improved terminal device of the type described which provides a low resistance, highly conductive connecting path between the ground sheath of the cable and the grounding means of the terminal without interference with the elastic deformation of the filler.

Still another object of the present invention is the provision of a new and improved terminal device of the type described having low resistance resilient conducting means embedded in the filler for providing a high current grounding path between the cable sheath and grounding means of the device.

Still another object of the present invention is the provision of a new and improved elastic filler for use with a terminal device of the type described including resilient conductive means embedded therein to provide a low resistance grounding path between the cable sheath and end fitting and also providing for a uniform symmetrical distribution of the electrical stress within the cable insulation to gradually reduce the stress gradient from the point where the cable sheath is discontinued.

Yet another object of the present invention is the provision of a new and improved elastic filler for use in a terminal device of the type described wherein the filler includes an upper non-conducting insulating portion and a lower conducting or semi-conducting grounding portion having low resistance resilient conductive means embedded therein for grounding the cable sheath to the grounding means of the device.

3,317,654 Patented May 2, 1967 These and other objects and advantages of the present invention are accomplished by the provision of a new and improved electrical terminating device for use with a high voltage cable having a central conductor, a concentric insulating cover around the central conductor and a concentric ground sheath around the insulating cover, the device comprising an insulating housing having a terminal at one end for connection with the central conductor of the cable and a mounting grounding clamp adjacent the other end of the housing for mounting the device and grounding the sheath of the cable. The housing defines an elongated cavity for receiving a terminal end portion of the cable and tubular elastic filler surrounds a portion of cable inserted into the cavity. A conductive end fitting encloses the lower end portion of the filler and applies an end force thereto to torce a filler into cavity against a compression spring disposed at the opposite end of -the filler. In accordance with the present invention, a resilient conductor is embedded in the lower portion of the filler. The conductor is formed of low resistance wire or the like having a high current capacity and includes inner contact portions engageable with the end of the cable sheath and outer contact portions engageable with the inner surface of the conductive end fitting, to provide alow resistance path between the cable sheath and grounding means of the device. The embedded conductor is flexible to move with the filler as the filler is deformed under end force as it is forced into the cavity. Since the conductor is low in resistance and capable of carrying high currents, fault currents or leakage from the cable sheath are readily grounded, thus preventing these components from damaging the filler or other components of the device.

For a better understanding of the present invention reference should be had to the following detailed description taken in conjunction with the drawings, in which:

FIG. 1 is an enlarged longitudinal sectional View of one embodiment of an electrical terminal device constructed in accordance with the present invention;

IF IG. 2 is a diagram showing several types of electrical cables which can be utilized with the terminal device of the present invention and showing these cables as they are prepared for use with the device;

FIG. 3 is an enlarged sectional view tion of the device of FIG. 1.

FIG. 4 is a transverse sectional view taken substantially along the line 4-4 of FIG. 3;

FIG. 5 is a fragmentary sectional View of the ller similar to FIG. 4 illustrating the filler in a relaxed or noncompressed condition ybefore insertion in the device;

FIG. 6 is a fragmentary sectional view of the filler similar to FIG. 5 but illustrating the deection of the conductive means in the filler when the filler is inserted into the housing of the device;

FIG. 7 is an enlarged partial sectional view similar to FIG. 3 of the lower end of another embodiment of a terminal device constructed in accordance with the present invention;

FIG. 8 is a transverse sectional view taken substantially along the line 8-8 of FIG. 7;

FIG. 9 is a transverse sectional View of the ller of FIG. 7 similar to the view of FIG, 8 but illustrating the filler in a relaxed or non-composed condition before insertion into the housing ofthe device;

FIG. 1() is an enlarged partial sectional View similar to FIGS. 3 and 7 of the lower end of yet another embodiment of a terminal device constructed in accordance with the present invention;

FIG. 11 is a transverse sectional view taken substantially along the line 11-11 of FIG. 10;

FIG. 12 is a transverse sectional view of the filler of FIG. 10 similar to FIG. 11 but illustrating the filler in a of the lower porrelaxed or non-compressed condition before insertion into the cavity;

FIG. 13 is an enlarged partial sectional view similar t0 FIGS. 3, 7 and 10 of the lower end of still another embodiment of a terminal device constructed in accordance with the present invention;

FIG. 14 is a transverse sectional view taken substantially along the line 14-14 of FIG. 13;

FIG. 15 is a transverse sectional view of the iiller of FIG. 13 similar to FIG. 14 but illustrating the ller in a relaxed or non-compressed condition before insertion into the cavity; and

FIG. 16 is an enlarged partial sectional view similar to FIGS. 3, 7, 10, and 13 of the lower end of still another embodiment of a terminal device constructed in accordance with the present invention.

Referring now to the drawings and especiallyFIGS. 1 and 3 through 6, there is illustrated one embodiment of an electrical cable terminal device referred to generally by the numeral 20. The device 20 is generally similar to devices illustrated and described in the aforementioned U.S. application and is adapted for use in terminating high voltage electrical cables, some of the better known and most widely used types of which are illustrated in FIG. 2.

The cables illustrated in FIG. 2 are referred to by the

reference numbers

22A, 22B, 22C, 22D, and 22E and are shown as they have been initially prepared in the eld in preparation for use with the terminal devices of the present invention. The cables are all essentially the same in electrical characteristics and all of them include a central conductor 24 surrounded by a concentric insulating cover 26 which is stripped back from the end of the cable a distance A when the cables are :being prepared for termination.

All of the cables include a concentric ground sheath means disposed around the insulating cover 26 and it is in the type and construction of the ground sheath means that the cables differ from one another, The cable 22A includes a lead ground sheath 28A which is stripped back a distance A plus B from the terminal end of the cable. The lead sheath 28A provides an outer protective jacket for the cable as well as a ground sheath. Beneath the lead sheath 28A is a spirally wound layer of semiconducting bedding tape 30A which is trimmed to extend upwardly a distance C from the stripped back end of the lead sheath 28A. The bedding tape 30A forms a part of the grounding sheath of the cable and is used t-o insure that the entire outer surface of the insulating 4cover 28A of the cable is maintained at ground potential even though f the lead sheath 28A may separate therefrom slightly because of sharp bends in the cable or other causes.

In the cable 22B the ground sheath means includes an inner layer of -bedding tape 30B and a plurality of longitudinally extending individual grounding wires 28B. The ground wires 28B are circumferentially spaced about the cable in intimate contact with the -bedding tape 30B and are held in place by an outer protective cable jacket 32B of tough polyethylene material. In preparing the cable 22B the conducting wires 22B of the sheath are bent downwardly at a point spaced a distance A plus B from the terminal end of the cable. The wires 28B are extended downwardly at least a distance D from the upper bends and are secured to the cable by wire ring 29B and are then twisted together to form a ground lead 31B for external connection to the grounding clamp of the terminal device. The bedding tape 30B is cut to extend a distance C above bends in the ground wires 28B similar to the cable 22A.

The cable 22C includes ground sheath means consisting entirely of a spirally wound conducting tape layer 30C. The tape layer 30C is covered by a concentric outer protective jacket 32C of tough polyethylene or neoprene similar to the jacket 32B of cable 22B. The jacket 32C is stripped back a distance A plus B from the terminal end of the cable and the tape layer 30C is cut to extend upwardly therefrom for a distance C.

Cables

22D and 22E differ from the cables 22A, 22B, and 22C in that they have outer ground sheaths formed of heavy conducting tape layers 30D and 39E, respectively, and no bedding tape is provided. The tape layer sheaths 30D and 36E are stripped back from the terminal ends of the cables and cut off at a distance A plus B from the end of the cable. The ground sheath means of cable 22D also includes a plurality of longitudinally extending spaced apart ground wires 28D which are bent downwardly at a point a distance D from the end of the tape layer 30D, The downwardly extending ends of the ground wires 28D are twisted together to form an external ground lead 31D and a ring of wire 29D is utilized for holding the wires in place in a manner similar to that shown in connection with the cable 22B. The cable 22D also includes an outer jacket 32D which is stripped back and trimmed at a point below the twisted ground lead 31D to expose the ground wires 28D as illustrated.

The cable 22E is similar to the cable 22D except that the -ground wires 28E are spirally wound around the tape `layer 30E rather than extending longitudinally of the cable. Also, an upper wire ring 29B is utilized to train the spirally wound ground wires adjacent the point at which the wires are bent downward-ly and no protective outer jacket is present on the cable 22E.

Returning now to the terminal device 20 of FIGS. 1 and 3 through 6, the device is there illustrated as it is used with cables of the type illustrated as cables 22A, 22B, and 22C of FIG. 2 and, for convenience, the cable 22A is chosen as typical of the three types, and the reference numerals used specifically refer to this type cable. The device 20 includes an elongated housing 34 constructed of a rigid, high strength insulating material such as porcelain or the like. The external surface of the housing is formed with a plurality of conventional annular ridges 36 and an annular recess 38 adjacent the lower end. Seated within the recess is a split ring type grounding and support clamp 40. The clamp 40 is secured in place around the housing with a bolt 42 and includes an outwardly extending mounting bracket (not shown) for mounting the device on an electrical panel or the like.

The housing 34 defines an elongated, generally cylindrical enlarged cavity 40 which is adapted to receive a terminal end portion of the cable and is formed with .a lower end surface 34a adjacent the lower end of the cavity. The upper end of the housing is partially closed by an inwardly extending flange 44 having a lower annular surface 44a forming an upper end wall of the cavity 40 and an upper annular surface 44b forming the top of the housing.

A terminal assembly 46 adapted for connection to the cent-ral conductor 24 is disposed at the upper end of the housing and includes a base flange 48 for seating on the surface 44b. The flange 48 includes a downwardly depending annular outer lip 48a encircling the outer periphery of the surface `44b and an O ring seal 52 is seated in a recess 48b in the lower surface of the ange 48 to bear against the surface 4417 and seal off the upper end of the housing.

The terminal assembly 46 includes a downwardly depending hollow shank 54 which extends downwardly through a central aperture 56 in the housing dened by the flange 444. The shank 54 extends past the flange 44 into the cavity 40 and is externally threaded adjacent its lower end to receive a collar or nut member 58 which holds the terminal block in place. A Belleville washer 60 is disposed between the upper surface of the nut member 58 and surface 44a to prevent the nut member from loosening after the terminal assembly is secured in place.

The terminal 46 is formed with a central bore 5() in order to accommodate an upwardly extending stem 62a of a compression connector fitting 462. The litt-ing 62 s is swedged onto the upper exposed end of the central conductor 24 of the cable by means of a conventional swedging tool and an O ring 64 is seated in a recess on the fitting for providing -a seal against the bore 50 to prevent leakage into the upper end of the cavity. The stem 62a is externally threaded to receive a connector nut 66 which secures the fitting 62 to the terminal assembly 34.

In order to provide for a 'gradual and symmetrical reduction in the electrical stress on the cable insulation from the point at which the ground sheath is discontinuous, an elongated tubular elastic filler 70 is inserted within the cavity to surround exposed portions of the insulating cover 26, and the sheath 28A and tape layer 30A. The filler 70 includes a non-conductive or dielectric upper portion 72 and a lower semi-conducting or conducting portion 74. The upper portion 72 is formed with a slightly tapered outer peripheral surface 72a adapted to engage the cylindrical wall of the cavity 40 yand an upper end surface 72b adapted to face the surface 44a of the flange 44. The lower end of the portion 70 is formed with an inwardly and downwardly tapered lower conical end surface 72C adapted to abut a mating conical surface 74a on the lower portion 74. The portion 74 of the filler is formed with a slightly tape-red outer peripheral surface 74b and an annular lower end surface 74C. Reference should be had to the aforementioned co-pending application concerning the amounts of taper of the

surfaces

72a, 72e, 74a, and 74b and the intersection of these surfaces with the cavity wall and `cable surface upon insertion of the filler into the cavity.

The filler 70 is forced into the cavity 40 under end force Iapplied by means of a `conductive end fitting 76 disposed at the lower end of the housing to lform an enclosure for the portion 7'4 of the filler `and lower end portion of the portion 72 of the filler. The fitting 76 includes an upper end flange 78, a generally cylindrical wall section A80 having an inturned annular flange 82 at the lower end; the flange 78 includes an annular surface 78a which abuts the lower end of the housing when the fitting is drawn upwardly to the position of FIGS. l and 3 by me-ans of upwardly extending draw 'bolts or cap screws `81 extending upwardly through the flange into threaded engagement with the grounding clamp 40. A thrust bushing 84 of high strength insulating material is carried -by the annular flange 82 to transmit the end force from the fitting to the lower end of the filler as the -cap screws 81 are tightened and a gasket 86 is positioned between the upper face of the bushing and the lower end of the filler in order to seal the lower end of the fitting from moisture or dirt penetration. The bushing is formed with a central aperture slightly la-rger than the cable so that the bushing may be easily slipped onto the cable during installation and bushings having various different aperture sizes can be utilized with an end fitting of a given size in order that various sizes of cables can be accommodated. After initial insertion of the upper portion 72 of the filler into the cavity, the cap screws 81 are threaded into the grounding clamp 40 and are tightened to draw the end fitting 76 upward toward the housing. As the fitting is drawn upwardly by the cap screws, end force is applied through the bushing 84 yand gasket 86 to the lower end 74C of the fillei to force it into the cavity.

In order to maintain end compression on the filler after it is inserted into the cavity and to insure that end force is continually maintained even though temperature conditions may change, a compression spring unit 88 is disposed in the upper end of the cavity to exert a downward end force against the upper end 72b of the filler. Preferably, the spring unit 88 is of the type disclosed and claimed in a `co-pending application of Walter Hornberger, Ser. No. 403,211, filed Oct. 12, 1964, and assigned to the same assignee as the present invention and includes upper and lower restraining members 88a and 88h, re-

spectively, interlocked together to maintain the spring in a precompressed condition so that insertion of the Ifiller is easier. When changes in temperature conditions cause the filler to contract in length, the spring unit 88 will expand to continually exert end force on the filler to maintain the filler under pressure so that the interfaces between the filler and cavity wall and between the filler and cable will remain in substantially air-free interfacial engagement. A bearing washer 90 is disposed between the lower end of the spring unit 88 and the upper end 72b of the filler to distribute the force of the spring over the entire cross-sectional area of the filler.

In accordance with the features of the present invention, the lower conducting portion 72 of the filler is formed with a resilient conductor 92 embedded therein for providing a low resistance, high current capacity electrical connection between the tape layer 30A of the cable and the internal surface of the cylindrical wall of the end fitting. In the embodiment shown in FIGS. l and 3 through 6 the conductor 92 takes the form of a spring, Wound in a toroidal shape from a continuous length of low resistance, relatively flexible conducting wire. The spring includes a plurality of continuously interconnected loops 94 arranged to normally extend in a generally radial direction from the central axis of the toroid. Each of the loops 94 includes an inner contact portion 94a and an outer contact portion 94b. Although each loop is connected to adjacent loops on either side, the loops are spaced from one another by the elastomeric material of the filter, and because of the radial arrangement of the loops adjacent inner contact portions 94a are closer together than the outer contact portions 94b. The inner contact portions 94a are arranged to contact the grounding tape layer 30A of the cable generally tangential to the upper end of the tape layer as shown in FIG. 1 and the contact portions form a plurality of circumferentially spaced apart ground contacts arranged in circular configuration around the periphery of the tape layer. Likewise, lthe outer contact portions 94b form a plurality of ground contacts with the interior surface of the cylindrical wall 80 of the end fitting and the contacts are formed at circumferentially spaced apart points in circular configuration around the wall 80.

The spring conductor 92 is integrally molded within the elastomeric material of the portion 74 of the filler while in a relaxed condition and the loops 94 are thus arranged in a generally radial configuration with respect to the axis filler as shown in FIG. 5. In order to aid in bonding the conductor spring to the material of the filler, and to prevent air pockets from developing around the spring during molding of the filler, a coating which is compatible and adhesive to the filler material is first applied to the spring as by dipping or spraying. When the coated spring is then placed in the mold the filler material entering the mold adheres to the coating and eliminates the possibility of air pockets developing and provides a good bond between the spring and filler material. Care is exercised during this molding operation to insure that the inner and outer contact portions 94a and 94b are free from coating by the filler material. As shown in exaggeration in FIG. 5, the contact portions may protrude slightly from the surface of the molded material after the molding is completed. These protruding portions are cleaned by emery paper or the like after molding to remove any coating or filler material to insure that good contact between the tape layer 30A and wall 80 will ybe obtained when the filler is inserted into the end tting.

From FIG. 4, it can be seen that the wall 80' is tapered slightly inwardly toward the lower end. The portion 74 of the filler is slightly larger in diameter than the internal diameter of the wall portion 80 so that as the end tting 76 is drawn upwardly toward the housing upon tightening of the drawbolt 81, the lower end of the filler portion 74 is compressed inwardly around the cable in addition to being subjected to the upward end force necessary to force the filler into the cavity 40. As this occurs, the loops 94 of the conductor spring shift from their normally radial position of FIG. to the position shown in FIG. 6 wherein the outer portions of the loops approach a tangential position relative to the cable and end fitting. Also, during this shifting action each loop is lcompressed slightly to become egg shaped or elliptical and thus `the loops are under stress, which insures good contact between the loops and the tape layer 30A and wall 80 of the end fitting.

As can -be seen in FIG. 6, the elastomeric material of the filler portion 74 completely fills the voids between the outer and inner portions of the loops and insures a substantially air-free interfacial contact between the filler and the cable and between the filler and the end fitting. During deformation of the lower end of the filler portion 74, as just described, the conductor spring is flexible and can follow the movements of the filler material with no break in the bonding action between the two. It should also be noted that each individual loop 94 serves as an individual current carrier between the tape layer and end fitting in parallel with every other loop so that a highly conductive, low resistance ground path is provided.

Any appreciable ground current developing in the cable sheath 28A during operation is readily passed from the tape layer 30A of -the cable to the end fitting 76 through the conductor spring 92. Without the conductor spring 92 such a ground current would have to pass through the semi-conducting elastomeric material of the filler portion 74 which might result in damage to the filler. Also, the filler itself would provide a fairly high resistance path between the cable and end fitting which would result in the cable sheath being maintained at a potential some- 'what above ground potential.

When the end fitting 76 is drawn fully upward into the position shown in FIGS. 1 and 4, all of the air is substantially excluded between the `interfacing surfaces of the filler and cable and between the filler and the cavity 40 and the end fitting. This provides -for a uniform and symmetrical increase in insulation around the cable from the lower end of the upper filler portion 72 upwardly. Air is also excluded from between the interfacing surfaces 72c land 74a of the filler members and the -surface 74a, being at ground potential, provides for symmetrically outwardly and upwardly directed lines of equipotential as shown by the lines 73 of FIG. 4. Thus, the conducting portion 74 of the filler develops the desired symmetrical stress pattern around the cable and the conductor spring 92 embedded therein provides la high current capacity, low resistance path to ground the 'cable -sheath to the end fitting.

In order to use the terminal device 20 to terminate a cable such as the cable 22A, the cable is initially prepared in the manner previously described and illustrated in FIG. 2 and the connector fitting 62 is secured on the exposed end of the central conductor 24. The end fitting 76 with bushing 84 Aand gasket 86 therein is slipped over the end of the cable end downward to a point below the end of the lead sheath 2SA. The lower filler portion 74 is slipped over the end of the cable and moved downwardly until the embedded lconductor spring 92 is in contacting position with the tape layer 30A. A coating of silicone grease is then applied to the lower conical surface 72e of the upper filler portion 72 and this portion is then slipped onto the end of the cable land moved downwardly until the surfaces 72C and 74a of the two filler portions are in contact. Silicone grease is then -applied to the surfaces 74c, 74b, and 72a of the assembled filler and the bearing washer 90 is positioned on the upper end of the filler. The cable and filler assembly is then inserted upwardly into the cavity 40 of the housing 34 and the upper stem of the connector 62 is guided into the bore 56 on the terminal 46 at the upper end of the housing.

The nut 66 is threaded onto the connector 62 and tightened to secure the -cable to the terminal, and the drawbolts 81 are inserted into the ground clamp ring 40 and tightened to draw the end fitting 76 upwardly to apply end force to the lower end of the filler. As the end fitting is moved upwardly, the filler is squeezed radially inwardly against the cable and interfacial contact is developed between the filler and the cable and between the filler and the lcavity and wall 80 of the end fitting. Because of the taper of the filler the interfacial contact expands progressively upward and downward from the region near the lower end of the housing and progressively excludes the air from between the interfacing surfaces. As the filler is more fully inserted into the cavity during tightening of the drawbolts 81, the spring unit 88 is compressed and exert-s a downwardly resilient force against the filler to maintainA the compression therein. The conductor spring 92 in the filler portion 74 is compressed inwardly 'and the loops 94 thereof may shift from the normally radial position of FIG. 4 toward the more tangential position of FIG. 6. Each loop is also compressed slightly to insure positive contact between the inner contact positions 94a and the tape layer 30A and the outer contact portions 94h and the end fitting wall 80.

When the drawbolts 81 are fully tightened, the end fitting 76 abuts the lower end of the housing as shown in FIG. l and the device is ready `for operation. The spring unit 88 is in a compressed condition and exerts a compressive force on the upper end of the filler to maintain the interfacial contact `at all times during changes in temperature conditions in the device. Should a fault in the line develop and the sheath 28A develop any potential above a ground level, the lcurrent will be shunted through the conductor spring 92 yand end fitting to the ground clamp 40 and thus the elastomeric material of the filler portion 74 is not subjected to heavy current ow. The device is easily disassembled by loosening the nut 66 and drawbolts 81 and pulling the cable, filler, and end fitting assembly downwardly.

Referring now to FIGS. 7 through 9, there is illu-s? trated another embodiment of a terminal device constructed in accordance with the present invention and referred to as a whole by the reference numeral 120. Many of the components of the device are identical with those of the device 20 and only the differences between the devices will be described in detail. Reference numbers applied to elements of the device 120 having counterparts in the device 20 are the same with an ladded prefix digit "1. As an example, the housing 34 of the device 20 is identified as 134 in the -device 120. Since the upper portion of the device 120 is identical with that of the `device 20 only the lower portion is illustrated in the drawings and the device 120 is illustrated as utilized with the cable 22A although it is to be understood that the cables 22B and 22C could also be utilized therewith.

In the device 120 a single-piece filler 170, formed entirely of non-conducting elastomeric material, is utilized rather than'a two piece filler with conducting and non-conducting portions. An end fitting 176 bushing 184 and gasket 186 identical to those of the device 20 are utilized to enclose the lower end of the filler and apply end force thereto to force the filler into the cavity 140.

In order to insure a highly conductive, low-resistance ground path between the tape layer 30A of the cable and the wall of the end fitting a resilient conducting member 192 somewhat different from the toroidal conductor spring 92 is embedded in the lower portion of the filler 170. The conducting member 192 includes an outer ring 193 disposed at the lower end of the filler and having an outer Contact surface 193a dimensioned to lie flush with the outer periphery of the filler for contact with the internal surface of the wall 180 of the end tting. The ring 193 is preferably split so that it will contract inwardly to a smaller diameter as the slightly tapered lower end portion of the wall 180 is moved upwardly to enclose the lower end of the filler.

In order to connect the ring 193 which is in contact with the end fitting 176 to the tape layer 30A of the cable and thus ground the cable sheath, a plurality of upstanding spaced apart resilient finger members 194 are spot welded or soldered to the inner surface of the ring at circumferentially spaced intervals thereabout. The fingers 194 are formed of spring wire having low resistance, high conductivity characteristics and include upstanding outer segments 19411 with radially inwardly extending looped upper end segments 194b having inner contact portions 194C thereon for contacting the tape layer 39A adjacent its upper end. As can -be seen from FIG. 9 the inner contact portions 194e of the fingers extend slightly inward of the adjacent elastomeric material of the filler when the filler is in la relaxed or non-compressed condition so that when the filler is slipped over the cable good electrical contact will be insured between the fingers and the tape layer 30A of the cable. The internal diameter between diametrically opposed fingers 194 in FIG. 9 is slightly less than the diameter of the tape layer 30A so that when the filler is slipped over the cable the fingers will be deflected slightly outwardly and consequently will exert an inward force against the tape layer to insure good contact therewith.

In order to provide additional grounding between the tape layer 4and end fitting and to provide for the desired distribution of electrostatic force lines 173 Within the filler a plurality of relatively long upstanding finger members 195 are spaced alternately between the fingers 194. The fingers 195 are also `spot wel-ded or soldered to the interior surface of the ring 193 at circumferentially spaced apart positions thereabout `an-d are likewise formed of similar resilient spring wire. These fingers include axial upstanding outer 'segments 195:1 which extend upwardly beyond the tape 4layer 30A a considerable distance and then are bent radially inwardly to form gradually curved sections 19512 having inner contact portions 195e at the lower ends thereof in cont-act with the tape layer. The fingers 195 are likewise moved slightly outwardly when Ithe filler is slipped over the cable :and hence bear inwardly with spring force against the tape layer 30A to insure good contact therewith. In addition to their function as grounding paths between the tape layer and end fitting, the `fin-gers 195 serve to shape the electrical stress pattern in the filler above the end of the tape layer in a manner similar to that -accomplished lby t-he conical surface 74a of the conducting filler portion 74 of the device 20. Since the segments 195b of the finger 195 slope gradually upwardly and outwardly away from the upper end of the tape layer 30A, a uniformly symmetrical stress pattern is developed in the filler as shown 'by the stress lines 173.

The lingers 194 and 195 are `securely attached to the ring 193 at their lower ends, leaving the upper ends of the fingers free to m-ove with the 4filler as it is compressed. When the filler is slipped over the end of the cable and the end fitting 176 drawn upwardly to enclose the lower portion o-f the filler and supply an upward end force thereto, the -filler is compressed inwardly a-roun-d the cable. As this occurs the free ends of the fingers move from their normal radial arrangement of FIG. 9 toward a more tangential position as shown in FIG. 8, and the inner contact portions 194C and 195e of the fingers press inwardly against the tape layer 30A to insure good contact therewith at a plurality of circumferentially spaced apart points about the periphery of the layer. This insures a low resistance ground path between the tape layer and the end fitting and additionally the longe-r fingers 195 serve to shape the electrostatic -field as described to reduce the electrical stress in the cable insulation 26 symmetrical manner above the point where the tape layer 30 is discontinuous.

Referring now to FIGS. 10 through 12, there is illusstrated another embodiment of a terminal device constructed in accordance with the present invention and referred to generally by the reference number 220. Many of the components of the device 220 are similar or identical to those of the

devices

20 and 120` and since the upper portion of the devices-are identical, only the lower portion of the device 220 is illustrate-d and described herein. Reference numbers applied to the elements of the device 22) having counterparts in the devices 20 and are the same with an added prefix digit 2. As an example, the

housing

34 and 134 of the devices Ztl and 120, respectively, is identified as 234 in the device 220.

The device 220 is adapted for use with any of the cables 22A, 22B, and 22C but for convenience the device is shown and described as used with cable 22A .as typical of ail. A single piece filler 270 constructed entirely of non-conducting elastomeric material similar to the filler is utilized in the device 220, and a conductor unit 292 somewhat different in construction from the conductor spring 92 and unit 192 is embedded in the lower end of the filler 270 to provide a low resistance, highly conductive ground path 'between the tape layer 30A and end litting 276. The unit 292 also serves to shape the electric field in the cable insulation and filler above the point where the tape layer 30A is discontinued in a manner to provide a uniform and symmetrical decrease in electrical stress in the cable insulation as indicated by the upwardly and outwardly diverging lines of equipotential 273.

The conductor unit 292 includes a pair of parallel axially 'aligned ring members 293A and 293B embedded within the filler member to surround the cable at points just above and below the upper end of the tape layer 30A. The rings 293A and 293B support a plurality of normally radially oriented loop members 294 having looped upper and lower ends which extend inwardly through the rings and are Ispot welded or soldered thereto. Each loop 294 includes an inwardly extending section having an inner contact portion 294a which contacts the tape layer 30A adjacent its upper end and pair of outer contact portions 294b at the outermost extremities of the upper and lower looped end portions for contacting the interior surface of the wall 280 of the end fitting. The loops are formed of low resistance resilient spring wire and provide a plurality of parallel grounding paths between the tape layer and the end fitting. The upper portion of the loops 294 serve the additional purpose of shaping the electric field as previously described, since these portions slope upwardly and outwardly from the upper end of the tape layer.

When the filler 270 is slipped into the cable and the end fitting is then ldrawn upwardly to compress the filler inwardly around the cable and apply upward end force thereto, the loops 294 move from their normally radially extending positions of FIG. l2 toward the more tangentially oriented positions of FIG. ll. The inner contact portions 294g form a plurality of circumferentially spaced contact points encircling the upper end of the tape layer and the outer contact portions 294b for-m a pair of concentric rings of contact at circumferentially spaced points with the inner surface of the wall 280 of the end fitting. Since the loop members 294 are secured only at their end portions to the rings 293g and 293b the major portion of the members is fiexible with the material of t-he filler and when the filler is compressed, as shown in FIG. 12, the loop members exert force inwardly against the tape layer and outwardly against the end fitting to insure good electrical contact therebetween.

Referring now to FIGS. 13 through l5, there is illustrated vanother embodiment of a terminal device constructed in accordance with the present invention and indicated by the reference numeral 320. Many of the components of this device are similar or identical with those of the previous devices and since the upper portions of the devices are similar, only the lower portion of the device 320 is illustrated and described in detail. Reference numbers having the added prefix digit "3 will be l 1 used on elements of the device 320 similar or identical to the same elements of previous embodiments.

The device 320 includes a housing 334 with a cavity 340 therein for receiving the upper portion of a tubular filler 370 constructed entirely of non-conducting dielectric elastomeric material. The lower portion of the filler is enclosed by an end fitting 376 and end force is supplied to the lower end of the ller by a fiange 382 of the end fitting and a bushing 384 and gasket 386. The device is adapted for use with any of the cables 22A, 22B, or 22C and for convenience the cable 22A is shown as a typical type of installation with the device.

A lower resilient conductor spring 392 is embedded in the filler 370 and is in all respects similar in construction and function to the conductor spring 92 of the device 20 and for this reason will not be discussed in detail. Additional upwardly spaced-apart resilient conductor springs 393, 394, and 395, similar in construction to the spring 392, are embedded in the filler and each of these springs is formed with a progressively larger internal diameter as illustrated in FIG. 13. The function of these springs is to shape the electrical field as previously described and each spring is spaced upwardly from a preceding one by a short distance and acts independently thereof. All of the springs are of a common outer diameter in order that outer contact portions on each loop of the springs will be in Contact with the internal surface of the wall 330 and thus the spring be maintained at ground potential with the end fitting. The loops of upwardly spaced springs are progressively smaller than those of preceding lower springs, as shown in the drawing, so that ground potential within the filler is moved farther and farther away from the center adjacent the cable above the upper end of the tape layer 30A. When the fitting 376 is drawn upwardly to enclose the lower end of the filler and compress it against the cable, the springs will tend to shift from their radial loop orientated loop configuration, as shown in FIG. 14. This shifting will be progressively larger in the lower springs than in the upper smaller springs and in the uppermost spring 395 may be very small indeed.

By providing a plurality of spaced springs progressively larger in internal diameter upwardly from the tape layer 30A of the cable the electrical field in the cable and filler is uniformly and symmetrically patterned as indicated by the equipotential lines 373, and the device 320 thus achieves results similar to those of the

devices

120 and 220 which utilize resilient conducting members to shape the electric field rather than a conducting filler portion in the device 20.

Referring now to FIG. 16, there is illustrated yet another embodiment of a device constructed in accordance with the features of the present invention and referred to generally by the reference number 520. Again many of the components of this device are similar to those of the previous embodiments and hence only the lower portion of the device is illustrated and described in detail. Reference numbers with the added prefix digit 5 Will be used on elements of the device 520 having similar or identical counterparts in the previous embodiments.

The device 520 is adapted for use with cables such as

cables

22D and 22E which do not have grounded bedding tape layers such as 30A, 30B, and 30C of the cables 22A,- 22B, and 22C and because of this fact a two piece filler is used having an upper non-conducting dielectric portion 572 and a lower conducting or semi-conducting portion 574 similar to those of device 20.

A resilient conductor spring 592 similar to the spring 92 is embedded in the lower portion of the filler portion 574. The spring unit 592 is similar in construction and function to the spring 92 except that it is positioned at a lower level within the filler so that inner contact portions 39411 of each loop 394 of the spring will directly contact the upper end of the shield tape 30D and outer contact portion 394b will contact the internal surface of the wall 580 of the end tting. The lower portion of the central bore of the filler portion 574 is enlarged somewhat to accommodate the relatively thick shield tape 30D and the upper portion of the bore is dimensioned to fit closely around the cable insulation 26. Since the lower conducting filler portion 574 is in direct contact with the cable shield tape 30D it is maintained at ground potential and the upper conical surface 574a serves to shape the dielectric field in the cable insulation and upper filler portion 572, as indicated by the equipotential lines 573. It is to be understood that the device 520 can be utilized with cables 22A, 22B, and 22C as well as with the

cable types

22D and 22E since in the case of the former type cables the spring unit 592 will contact the upper end of the

bedding tapes

30A, 30B, and 30C, and in the latter types the unit will contact the

shield tapes

30D and 30E directly. Also, it is to be understood that the

devices

120, 220, 320, and 420 can be utilized with the types of cables7 such as 22D and 22E by repositioning the resilient spring unit lower in the filler so that contact is made directly to the

shield tapes

30D and 30E since there is no 'bedding tape on these cables.

The present invention thus provides a new and unique means for grounding the cable sheath means to the end fitting internally of the fitting without interference with the action of the elastic filler. The devices of the invention are adaptable for use with a variety of different cable types commonly available and provide a low resistance, high current capacity connection between the sheath of the cables and the grounded end fittings and additionally provide for the proper dielectric stress pattern distribution within the cable insulation and filler the point or region at which the sheath means are discontinuous.

While there have been illustrated and described several embodiments of the present invention, it should be understood that numerous changes and modifications will readily occur to those skilled in the art, .and it is intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope .of the present invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A device for terminating an electrical cable of the type having a central conductor, a concentric insulating cover around the central conductor and a concentric conducting ground sheath surrounding said cover, said device including a rigid housing of insulating material having an electric terminal disposed at one end, said housing defining an open-ended elongated cavity for receiving a terminal end portion of said cable, an elongated tubular dielectric elastic filler surrounding an end portion of said insulating cover and an end portion of ground sheath insertable with said cable into the open end of said cavity, conductive end fitting means for enclosing the lower end of said filler and applying endwise force thereto to force said filler into said cavity and form substantially air free interfacial engagements between said filler and the wall of said cavity and between said filler and said cable, and resilient low resistance conducting means embedded in the lower end of said filler, said conducting means having outer contact portions disposed to contact said end fitting means in a circular configuration and having inner contact portions disposed to contact the end of said conducting sheath in circular engagement. Y

V2. A device for terminating `an electrical cable of the type having a central conductor, a concentric insulating cover around the central conductor and a concentric conducting ground sheath surrounding said cover, said device including a rigid housing of insulating material having an electric terminal disposed at one end, said housing defining an open-ended elongated cavity for receiving a terminal end portion of said cable, lan elongated tubular dielectric elastic filler surrounding an end portion of said insulating cover andan end portion of ground sheath insertable with said cable into the open end of said cavity, said filler including an upper portion of non-conductive material and a lowerportion formed of conducting material, said lower portion having an upwardly extending conical surface diverging outwardly from the bore thereof, conductive end fitting means for enclosing the lower end of said filler and applying endwise force thereto to force said filler into said cavity and form substantially `air vfree interfacial engagements between said filler and the wall of said cavity and between said filler and said cable, and resilient low resistance conducting means embedded in said lower conducing portion of said ller below said conical surface, said conducing means having outer portions disposed to contact said end fitting means in circular configuration and having inner portions disposed to contact the end of said conducting sheath in circular engagement.

3. A device -for terminating lan electrical cable of the type having a central conductor, a concentric insulating cover around the central conductor and a concentric conducting ground sheath surrounding said cover, said device including a rigid housing of insulating material having an electric terminal disposed at one end, said housing defining an open-ended elongated cavity for receiving a terminal end portion of said cable, .an elongated tubular dielectric elastic filler surrounding an end portion of said insulating cover and an end portion of ground sheath insertable with said cable into the open end of said cavity, conductive end fitting means for enclosing the lower end of said filler and applying endwise force thereto to form substantially -air free interfacial engagements between said filler and the wall of said cavity and between said filler and said cable, and resilient .low resistance conducting means embedded in the lower end of said filler, said conducting means formed of a toroidal spring having a plurality of'outwardly extending loops, each loop having an outer contact portion disposed to tangentially contact an inner surface of said end fitting means at a point circumferentially spaced from a contact region of an adjacent loop and having inner contact portions disposed to tangentially contact said conducting sheath at a point circumferentially spaced from a contact region of an adjacent loop.

4. Apparatus as defined in claim 3 wherein said loops of said toroidal spring are embedded in said filler in a generally radially extending configuration and are mov- .able to a non-radial arrangement when said filler is enclosed with said conductive end fitting means.

5. Apparatus as defined in claim 1 wherein said conducting means includes a plurality of conductors ernbedded in said filler each having an outer contact portion and an inner contact portion thereon, said conductors disposed in a generally radial direction in said filler and the outer portions thereof being tangentially deflectable when said filler is compressed into said end fitting means and forced into said cavity.

6. A device for terminating an electrical cable of the type having a central conductor, a concentric insulating cover around the central conductor and a concentric conducting ground sheath surrounding said cover, said device including a rigid housing of insulating material having an electric terminal disposed at one end, said housing defining an open-ended elongated cavity for receiving a terminal end portion of said cable, an elongated tubular dielectric elastic filler surrounding an end portion of said insulating cover and an end portion of ground sheath insertable with said cable into the open end of said cavity, conductive end fitting means for enclosing the lower end of said filler and applying endwise force thereto to force said filler into said cavity and form substantially air free interfacial engagements between said filler and the wall of said cavity yand between said filler and said cable, first resilient low resistance conducting means embedded in the lower end of said filler, said conducting means having outer contact portions disposed to contact said end fitting means in circular configuration and having contact inner portions disposed to con- Vtact the end of said conducting sheath in circular engagement, and a second group of resilient conductors embedded in said filler spaced upwardly from said first resilient conductor means, said second group comprising a plurality of independent continuous, resilient conducting members spaced progressively upward from one another in said filler, each of said members including a plurality of circumferentially spaced outer contact portions contacting said end fitting means and a plurality of circumferentially spaced inner portions, said inner portions of upwardly adjacent conducting members being spaced progressively farther outward from said internal bore of said tubular filler.

7. Apparatus as defined in claim 6 wherein said first conducting means comprises a toroidal spring having a plurality of normally radially extending loops, each loop having an outer and inner contact portion thereon and the outer portions of said loops -being tangentially deflectable when said filler is enclosed in said end fitting means and forced into said cavity, each of said conducting members of said second group comprising a toroidal spring having an outer diameter substantially equal to the outer diameter of said first conducting means and upwardly adjacent conducting members having inner diameters progressively larger than an adjacent lower member.

8. A device for terminating an electrical cable of the type having a central conductor, a concentric insulating cover around the central conductor and a concentric conducting ground sheath surrounding said cover, said device including a rigid housing of insulating material having an electric terminal dispose-d at one end, said -housing defining an open-ended elongated cavity for lreceiving a terminal end portion of said cable, an elongated tubular dielectric elastic filler surrounding an end portion of said insulating cover and an end portion of ground sheath insertable with said cable into the open end of said cavity, conductive end fitting means for enclosing the lower end of said filler and applying endwise force thereto to force said filler into said cavity and form substantially air free interfacial engagements between said filler and the wall of said cavity and said filler and said cable, and resilient low resistance conducting means embedded in the lower end of said filler, said conducting means inclu-ding a plurality of radially extending spaced apart conductors, each conductor including upper and lower spaced apart outer contact portions disposed to contact said end fitting means in spaced circumferential engagement from adjacent conductors and an inner contact portion between upper and lower contact portions disposed to contact the end of said conducting sheath in circumferentially spaced engagement about said sheath.

9. Apparatus as defined in claim 8 wherein said conductors are formed with looped upper and lower ends with said upper and lower contact portions disposed on the outer extremities of said looped ends to tangentially contact said end fitting means.

10. Apparatus as defined in claim 9 wherein the upper and lower ends of said conductors extend inwardly toward said cable and conduct-ing concentric ring means embedded in said fille-r between the outer periphery and tubular bore thereof are connected to secure the respective ends of said conductor in spaced circumferential relation thereabout.

11. Apparatus las defined in claim 8 wherein said conductor includes inwardly curved central portions having said inner contact portions thereon disposed to -tangentially contact said sheath at the innermost portion of said conductors.

12. A device for teminating an electrical cable of the type having a central conductor, a concentric insulating cover around the central conductor and a concentric conductive ground sheath around said insulating cover, said device including a rigid housing of insulating material having .an electrical terminal at one end for connection to the central conductor of said cable, said housing defining an open-ended elongated cavity for receiving a terminal end portion of said cable, an elongated tubular dielectric elastic -ller surrounding an end portion of said insulating cover of said cable and an end portion of said ground sheath and insertable with said cable into the open end of said cavity, conductive end iitting means for enclosing a lower end portion of said iiller and applying an endwise force thereto to force said filler into said cavity and form substantially air free interfacial engagement between said filler and the wall of said cavity and between said filler and said cable, and low resistance resilient conductive means embedded in the lower portion of said filler, said means including an outer ring eng-ageable with the internal wall of said end fitting means and a plurality of upwardly extending resilient conductors connected to said ring and spaced apart from one another, said conductor having upper end portions curved inwardly to contact the end of said cable sheath at points spaced around the periphery thereof.

13. Apparatus as deiined in claim 12- wherein said conductors extend upwardly above the end of said cable sheath land curve downwardly and inwardly to tangentially contact the upper end thereof.

14. Apparatus as defined in claim 13 wherein alternately spaced ones of said conductors around said ring means are provided with circular loops at the free ends thereof with the inner surf-aces of said loops contacting said cable sheath.

15. An elongated tubular elastic iiller for surrounding a terminal end portion of an elect-rical cable and adapted for insertion therewith into an elongated cavity formed in a terminal housing of a terminal device, said filler including a lower end portion having a surface segment of its central bore adapted to closely engage and encircle a porti-on of a ground sheath of said cable land an outer peripheral surf-ace adapted to closely engage a ground fitting of said terminal device, and low resistance resilient conductive means embedded in the lower end portion of said filler, said conductive means including inner contact portions within said surface segment of said ller dispose-d to electrically engage said cable ground sheath and outer contact portion extending to said peripheral surface of said filler adapted to electrically engage said ground fit-ting of said terminal device for providing a low resistance path between the cable ground sheath and said ground fitting of said terminal device.

16. Apparatus as dened in claim 15 wherein said conductive means includes spring means having a plurality of generally radially extending loops, each loop including one of each of said inner and outer contact portions and being deectable toward a tangential configuration relative to said cable when said filler is inserted into the cavity of said lower end portion.

17. Apparatus as deiined in claim 15 wherein the lower end portion of said ller is formed of semi-conductivev material and is provided with an upper truste-conical end surface disposed to slope upwardly and outwardly away from said cable and said fille-r, also including an upper end portion formed of non-conductive material and having a lower end surface of frusto-conical shape adapted to closely contact the frusta-conical surface of the lower end portion of said iller in a substantially air free interfacial engagement.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES Electrical wond, v01. 16o, No. 21, Nov. 18, 196s, page LARAMIE E. ASKIN, Primary Examiner.

Claims

15. AN ELONGATED TUBULAR ELASTIC FILLER FOR SURROUNDING A TERMINAL END PORTION OF AN ELECTRICAL CABLE AND ADAPTED FOR INSERTION THEREWITH INTO AN ELONGATED CAVITY FORMED IN A TERMINAL HOUSING OF A TERMINAL DEVICE, SAID FILLER INCLUDING A LOWER END PORTION HAVING A SURFACE SEGMENT OF ITS CENTRAL BORE ADAPTED TO CLOSELY ENGAGE AND ENCIRCLE A PORTION OF A GROUND SHEATH OF SAID CABLE AND AN OUTER PERIPHERAL SURFACE ADAPTED TO CLOSELY ENGAGE A GROUND FITTING OF SAID TERMINAL DEVICE, SAID LOW RESISTANCE RESILIENT CONDUCTIVE MEANS EMBEDDED IN THE LOWER END PORTION OF SAID FILLER, SAID CONDUCTIVE MEANS INCLUDING INNER CONTACT PORTIONS WITHIN SAID SURFACE SEGMENT OF SAID FILLER DISPOSED TO ELECTRICALLY ENGAGE SAID CABLE GROUND SHEATH AND OUTER CONTACT PORTION EXTENDING TO SAID PERIPHERAL SURFACE OF SAID FILLER ADAPTED TO ELECTRICALLY ENGAGE SAID GROUND FITTING OF SAID TERMINAL DEVICE FOR PROVIDING A LOW RESISTANCE PATH BETWEEN THE CABLE GROUND SHEATH AND SAID GROUND FITTING OF SAID TERMINAL DEVICE.