US2222718A

US2222718A - Joint for high tension cables

Info

Publication number: US2222718A
Application number: US243804A
Authority: US
Inventors: Lester L Phillips
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1938-12-03
Filing date: 1938-12-03
Publication date: 1940-11-26
Anticipated expiration: 1957-11-26

Description

Nov. 26, 1940.

L. L. PHILLIPS JOINT FOR HIGH TENSION CABLES Filed Dec, 5. 1938 2 Sheets-Sheet l Inventor: L ,eter LMP-)bil HPS.

Hi Attorney.

NOV. 26, 1940. L L PHlLLlPS 2,222,718

JOINT FOR HIGH TENSION CABLES Filed Dec. 5, 1938 2 Sheetssheet 2 METAL/25D Figli. METAL/25o Inventor: Lester* L ,.Fhl lips,

His Att ormey.

Patented Nov. 26, 1940 PATENT OFFICE 2,222,718 JOINT FOR HIGH TENSIN CABLES Lester L. Phillips, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Application December 3, i938, Serial No. 248,30@b

I8 Claims.

My invention relates vto high tension cables of the single conductor type containing liquid insulation, such as degasied oil, under superatmospheric pressure. To limit the head pres- 5 sure where the cable is on a slope and also to limit the escape of liquid in case of a leak in the enclosing sheath, stop-joints are provided which segregate the cable into determined lengths or sections as regards the liquid without,

l however, interrupting the ow of current.

These stop-joints are necessarily of considerable size, are complex in construction and relatively expensive. As commonly constructed, the cost of installing them is a material item of eX- pense due to the large amount of hand Work which has to be done in the field by the cable splicers. In particular, one of the items of expense is the wrapping by hand of the metal parts designed to operate at high potential with insulating tape. As a specific illustration of which I have knowledge, a stop-joint of prior normal construction for a 138,000 volt cable requires approximately 1400 to 1500 yards of one inch Wide thin fabric tape which has to be applied smoothly layer by layer with the turns arranged to break joints. The wrapping also has to conform to certain electrical characteristics with the result that the completed body is thickest in the center region and tapering therefrom toward .both ends. The amount of tape required rapidly increases with joints for higher potential cables. Between the layers of tape, an insulating compound of an oily nature is applied which further increases the labor of properly applying the tape, and makes the job a tedious one. Also the Work of assembling numerous individual parts at the point of installation further increases the cost due to the extreme care with which the operations must be performed.

The object of my invention is the provision of an improved .stop-joint. More specifically stated, one of the objects of my invention is the pro- Vision of a stop-joint, the principal insulating parts of which are made at the factory in their final form and which may be readily assembled in place at the point of installation with a minimum amount of hand Work on the part of the splicer. A further object is the provision of a stop-joint wherein the amount of hand Wound or applied tape is reduced to a small fraction of that customarily employed for joints of similar ratings. A further object of my invention is an improved method of making cable joints.

For a consideration of what I believe to be f novel and my invention, attention is directed to the accompanying description andthe claims appended thereto.

In the accompanying drawings illustrating my invention, Fig. 1 is a view of approximately onehalf of a stop-joint with certain of the parts 1n longitudinal section; Fig. 2 is an enlarged View of the parts located at approximately the center of the joint; Fig. 3 is a detail sectional view taken on line 3 3 of Fig. 2 showing how certain of the parts shown in Fig. 2 are connected; Fig. 4 is a sectional view of the factory made cylinders which are assembled over the conductor ends; Fig. 5 is a cross-section taken on line 5-5 of Fig. 4 showing the oil grooves in one ofthe cylinders; Fig. 6 is a cross-sectional view of some of the factory made barrier tubes which are assembled around the joint; Figfl is a side view of a split ring for uniting parts of the connector, and Fig. 8 is a detail view showing the overlapping ends of the barrier tubes.

The necessary and desirable features of a stopjoint are (o) the provision of suitable means for controlling the flow of insulating liquid into and from the core of the cable; (b) the provision of means whereby the radial electric stresses to which the liquid is subjected may be controlled or conned within safe limits by a proper choice of conductor and casing diameters, and (c) the provision of means whereby the axial electrical stresses along the boundaries of the component solid insulations may be suitably controlled.

Approximately one-half of a joint is shown, the other half being a duplicate thereof. The complete joint is of the order of ninety-six inches in length with a maximum diameter of eighteen inches. The'particular joint illustrated is intended for hollow core, lead sheathed cable operating at 230,000 volts. These ligures are given merely for the purpose of illustration and not as limitations of my invention.

l, Fig. 2, indicates a part of one of the conductors having the usual factory spirally applied paper insulation 8, the other conductor being a .duplicate thereof.` The conductor is of the stranded type having a hollow core 9 which is lled with `degasiiied liquid, such as oil, under super-atmospheric pressure. The oil passes through the spaces between strands and impregnates the factory applied insulation 8. To electrically connect one cable length with the end of the next, a divided metal connector is provided, each part having a central bore I0 and an annular socket ll in which the strands of the conductor 'l are located. The connector and the cable strands are united by exerting compression pressure on the outer wall of the socket, as for example by indenting the connector wall by a suitable press and punch but other means may be employed for the purpose. To prevent the strands from being pushed inwardly during the pressing operation and thereby reduce the size of the oil channel in the core, a. strong metal tube I2 which may be made of steel is provided. The connector is also provided with a collar I3 and a tubular extension I4, the latter being externally screw-threaded to receive a clamping nut I5, the latter having a sen'es of small angularly spaced recesses I9 to receive a spanner wrench. The connector also has one or more radial ports I4m for oil opening at their outer ends into an annular space or chamber I1. Inside of the bore of each part of the connector is a valve I9 having exterior screw-threads engaging similar threads in the wall of the bore. As shown, fthe valve is seated and hence the radial ports Il are shut oif from communication with the oil in the core of the cable. This position of the valve is a temporary one used`during assembly. Before the half connectors are united, the valve will be moved, in this case to the right, to expose the ports Il so that oil may freely pass between the conductor core and the outside thereof. The valve in the other half connector will also be moved to expose the oil port therein. Surrounding the connector part are two preformed factory made cylinders I9 and 20 which will be referred to later. Located within the inner cylinder I9, Fig. 2, is a metal ring 2| which engages the collar I3 of a connector part. In the ring and in the inner cylinder are one or more radially disposed oil passages 22, in this case two, which communicate at their inner ends with the annular space or chamber I1, Fig. 2, and at their outer ends with oil grooves between the inner and outer cylinders I9 and 20. To unite the cylinder I9 and the ring, pins 23 are employed as shown in Fig.

. 3. These pins form a simple reliable means for uniting the parts but other means may be employed. The clamping nut I5 contacts with a side face of the ring 2| and also with the end of the inner cylinder I9 to hold the parts in place, and to provide current carrying capacity between parts Il and 29. In other words, the arrangement of the parts definitely fixes the axial positions of the cylinders I9 and 29. Since there would be a tendency for oil or other liquid, especially when heated, to pass from the cable into the joint' casing between the radial ange of the nut and the cylinders I9 and 20, a compressible packing 24 is provided and located in a cutaway portion of the flange near the periphery thereof. The packing should be elastic and may be made of an oil resisting rubber or rubber-like compound'. It is of ring form and is held against outward movement by the inner wall of the outer cylinder 20. The nut I5 also has an externally screw-threaded part 25 to receive the split clamping ring 29, Fig. 7, which electrically and mechanically connects the two main halves or parts of the connector, it being understood that each cable length has its halt connector.

A short portion of the factory applied insulation is removed to expose the conductor end preparatory to connector attachment ln socket II. Insulation removal to a shouldered contour. as indicated in Fig. ,2, may in some instances expedite the use of a connector attachment tool.

v'g Another portion of factory applied insulation is next removed to provide contours adapted to electrical stress control. As indicated in Fig. l, the removal leaves the remaining cable insulation with two appropriately tapered surfaces converging to approximately the conductor diameter. The tapered or cored surface 28 is vthen overlaid with metallic shielding braid 29 forming a stress cone to enforce a desired stressing of the insulation.

Finally, tape is applied in firmly drawn wrappings over the attached connector, the assembled braid, and the exposed paper insulation in the

regions

28 and 31. This tape should be wrapped to a smooth cylindrical surface having the diameter of the original cable paper.

The tape insulation should be of such material that it does not appreciably degenerate under heat from any cause. As an example, the tape may be made of fabric coated or impregnated with a binder made of varnish or other suitable material. By reason of the stepped construction and the adjacent cone covered by metallic braid 29, the electrical stress within the joint is reduced to the equivalent of a conductor of the diameter of the flanged nut. In this connection, it will be noted that instead of removing all of the factory applied insulation from the ends of the cables which are to be jointed, as is the customary practice, only a portion thereof spaced from the conductor end is removed and that by this procedure the benefit of the superior factory applied insulation on the extreme ends is retained. As will be seen from the drawings and particularly Fig. l, the removal of the factory insulation results in the formation of double opposed cones, one tapering from the outside diameter of the insulation to the conductor and the other tapering in the opposite direction from the conductor to the outside diameter of the factory insulation.

Instead of using a single preformed conical insulator over each conductor end in accordance with prior practice, which insulators are relatively diillcult to make and require special apparatus inltheir manufacture, cylinders I9 and 20 are employed arranged in telescopic relation and friction fitted one inside of the other. They are madev of sheets of paper or equivalent material and wound on suitable cylindrical mandrels or rolls, one or more of which are or may be heated. l

The sheets are coated or impregnated with a binding material of which condensation products are examples. The binder may be applied in liquid form or as a dry powder. The paper as it is wound is desirably subjected to heat and pressure with the ultimate effect of making hard dense cylinders of high dielectric strength. In one or both of the cylinders thus formed are channels or grooves 39, Figs. 4 and 5, which serve to convey oil between the core of the conductor and an outside source of supply. as for example through the fitting 3I mounted on an end of the enclosing metal casing. As it is a simpler machine operation to form the grooves on an outside surface than on an inside, they are formed on the inner cylinder I9. The inner ends of the grooves communicate with the radial passages 22, Fig. 2, the inner ends of which are in comat one end by the collar I3 of a connector member and thereby maintained in concentric relation with respect to the axis of the conductor. The outer cylinder is internally supported by the flanged part of a connector member.

In order to control the electrical gradients, the ends of the inner cylinder I9 have incorporated therein a conducting material which may take different forms. In the present instance, the edges of the paper of which the cylinder is composed before winding are metalized by a coat of so-called resistance paint in such manner that when wound, the metalized parts appear in longitudinal section in the form of cones, the outer surfaces of which are indicated by

lines

32 and 33, Fig. 1. In actual practice, the cones when viewed in section are distinguished from the main body by a difference in color. It will be noted that line 33 denes a cone and is a continuation of the cone formed by the shielding braid 29. It will also be noted that the braid 29 is at the potential of the conductor, that the braid and the metalized part of cylinder I9 are in contact at their point of meeting and that the outer or enlarged part of the cone dened by the contained metal is in electrical contact with the collar I3 of the connector, ring 2I and part I5 and hence at the same potential as the conductor and the braid. In this manner, an effective gradient is provided extending longitudinally of the joint. As previously stated, the parts of the joint on opposite sides of the center are alike. An advantage of this construction resides in the fact that the resistance paint is largely or wholly forced into the material of which the cylinders are composed so that the inner and outer diameters of the cylinders remain unchanged with respect to the main body thereof.

To avoid hand work on the part of the jointer or splicer as fully as possible, the preformed inner and outer cylinders are properly fitted one inside of the other at the factory and desirably with a close t so as to preserve the desired concentric and axial relationship. In addition to this, the

"

sections

34 and 35 of the metallic joint casing are pressure tted at the factory over the inner and outer cylinders so that in effect they form a unitary structure, and handled as such by the splicers. After the conductor insulation is stepped, the part 28 shaped to form a cone, the braid 29 applied, the connector secured to the conductor, and the reinforcing bodies of tape insulation in regions 28a and 31 applied, the cylinders I9 and 20 are slipped endwise into place after which the clamping nut I of each half connector is screwed into place. Mention has been made of first forming the double cone and then cutting away the end of the insulation to receive the connector, but these operations may be reversed, i. e. the ends prepared iirst. It will be noted that the grooves 30 between the cylinders extend into the end part 34 of the casing and that the inner cylinder I9 is somewhat smaller in diameter near its outer end than the casing as indicated at 38, thereby forming an annular space or chamber which communicates with all of the grooves 30. The fitting 3l also opens into the chamber. A reservoir or other source of supply under superatmospheric pressure is or may be connected to the tting to receive oil or other insulating liquid as it heats and return it as the cable cools.

In order to separate the oil contained in the conductors from that contained in the main or central part of the enclosing joint casing and also to prevent oil from one cable length flowing into the other through the joint casing, a shoulder 39 is provided between the

end sections

34 and 35 of the casing, best shown in Fig. 4, and at this point is located a ring packing 40 which engages the shoulder on one side and the end of the outer cylinder 2|! on the other. When the cylinders are pressure tted into the

metallic casing sections

34 and 35, the packing is compressed and held in that condition by the pressure tting of the parts. After the inner and outer cylinders I9 and 20 are mounted in place, the nut 25 seated and the split ring 25 mounted in place to unite the halves of the connector, a body of insulation 26a composed of a small amount of tape is wound in layers over the split ring and over the adjacent ends of the outer cylinder 2U, of which only one is shown in the drawings. At some time previous to applying the split ring 26, the valves I 8 are moved suiflciently to permit communication between the cable cores, the ports I4EL and grooves 30.

In order to further and properly insulate the` parts thus far described from the metal joint casing, numerous concentric barrier tubes 4I arranged in spaced relation are provided. The concentric spaced arrangement of the tubes is maintained by a series of insulating blocks 42 arranged at suitable angularly spaced intervals. The blocks have small notches 43, Figs. l and 6, to receive a binding band 43a made of insulating cord to hold them in their respective positions. As will be noted, the inner tubes are the longest and gradually decrease in length to the outer one. Since the greatest stresses are near the Center of the joint in planes transverse to the connector, a portion of the barrier tubes of the left-hand part of the joint overlap portions of the barrier tubes of the right-hand part as best shown in Fig. 8. In other words, the end portions of the barrier tubes are in telescopic relation. The barrier tubes may advantageously be made in the same manner as the cylinders I9 and 20 but they are of much thinner section.

Reference has previously been made to the end parts or sections of the metallic casing for the joint. The main or central part of the casing comprises two cylindrical members 45 arranged end to end, the outer parts 46 connected thereto are cone shaped and conform generally in shape to the arrangement of the ends of the barrier tubes. The outer ends of the parts 45 are wipe soldered at 41 to the end sections which carry the cylinders I9 and 2D and the end sections in turn are wipe soldered to the metallic cable sheaths as at 48.

Between the metallic casing members 45 is located a sheath insulator 49 made of a good grade of insulating material adapted to withstand without injury the effects of the oil within the casing and that of the atmosphere with which the joint is surrounded. To secure the insulator in place, the halves of the main casing are provided with circular flanges 50 through which securing means such as bolts or studs extend into or from the insulator.

The casing is provided with a tting 5I through whichinsulating liquid such as oil may be introduced into the casing to improve the insulating effects of the assembly. As previously indicated, this liquid is not permitted to enter thecable core due to the presence of packings 24, Fig. 2, and 40, Fig. 4, and may or may not be degasied. Insulating oil will withstand an electrical stress equal to approximately one-half that of a cylinder of equal thickness made of paper and a binder or varnished cloth tape. For this reason, the oil in the region where it emerges from the connector and enters the dielectric field requires a contacted metal diameter of approximately five inches for stresses existing in'a 230,000 volt joint. In the region of the cable connector where the diameter is approximately one inch, oil would be overstressed, therefore varnished cloth tape or equivalent material has to be used.

Electrical stresses imposed upon the boundary surfaces of two adjacent insulations in the dielectric depend upon the variation in conductor and enclosing casing diameters. In the present instance, the conductor diameter varies from approximately one inch to five inches, the latter being the diameter of the flanged nut I5. Conductor sections represented by these two extreme diameters should therefore vbe separated by eleven to twelve inches. A part of this length is obtained in effect by the cylinders I9 and 20,

and the remainder is accomplished by the braid covering 29 over the factory applied insulation on the stranded conductor ends.

The combination of the coned surface of the factory applied insulation with the metallic braid covering 29 and the metallization of the inner end of the tube I9 as indicated by the line 33, Fig. 1, gives in effect a gradual change from one inch diameter of the cable conductor to the five inch diameter of the connector. The final effect is the same as if the metal connector and the end portion of the cylinder I9 under the line 33 were united in one solid mass of metal.

Among other advantages of my improved joint are the following:

(a) The use of the two factory made cylinders I9 and 2|), which are pressure fitted into parts of the casing with oil channels between, results in a material decrease in the amount of hand labor the jointer or splicer has to perform at the place of installation, usually a manhole below the level of the street. Being machine made in the factory, Where the conditions are of the best, the insulation is more effective than when made by hand by a jointer, even under the best of conditions. There is also a substantial saving in cost.

(b) The use of conducting material in the ends of the cylinders provides adequate control of the electrical gradients axially along the joint.

(c) A very great reduction in the amount of reinforcing tape required and hence decreased initial cost and a great saving of labor on the part of the jointer, as compared with previous designs for the same voltages and types of service. The saving in tape and the labor of applying it is evident from the fact that the only bodies of tape required are those immediately around and adjacent the connector. In the joint herein illustrated for 230,000 volts, only about seven pounds of tape are required against about thirty pounds for a 138,000 volt joint of the previous design. A joint for 230,000 volts made in accordance with the prior common practice would require about forty-five pounds or approximately twenty-three hundred yards.

(d) The arrangement of the sheath insulator means that it can be installed by the jointer instead of being made an integral part of the joint casing, thereby making the joint easier to assemble.

(e) The fact that all the wipe joints are located at places where the diameters are small results in a saving of labor and means less likellhood of faulty workmanship.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A stop joint for fluid filled cables comprising insulated conductors, at least one of which has a fluid containing hollow core, a means for electrically connecting the conductors and preventing the passage of fluid from one conductor to another, a pair of preformed insulating cylinders arranged in close fitting telescopic relation surrounding a conductor, a fluid flow channel of relatively small cross-sectional area located between the cylinders which at one end is in communication with the core of a conductor, a casing part into which the outer ends of the cylinders are permanently secured, there being a chamber in the casing part in communication with the outer end of the channel, a wrapping of tape around the connecting means and a part of the outer cylinder, concentric barrier tubes surrounding the cylinders and held in spaced relation, and a casing surrounding the barrier tubes and connected at its ends to the casing parts in which ends of the cylinder are located.

2. A stop joint for fluid filled cables comprising a pair of insulated conductors each having a hollow core, a separately maintained body of fluid insulation in each of the cores, metallic connector members uniting the conductors electrically and mechanically and preventing the passage of fluid from one core to another, there being individual ports therein, pairs of cylinders made of dense insulating material in close fitting concentric arrangement, the inner cylinder of each pair being fitted over the insulation on one of the conductors, a casing having end portions in each of which ends of the cylinders are seated, each of the portions having a chamber, and a central portion connected to the end portions, a channel between each pair of insulating cylinders for conveying fluid from the core of an enclosed conductor to a chamber in the casing, barrier tubes in concentric spaced relation surrounding the major portion of the lengths of the cylinders and enclosed by the casing, and a filling of fluid for the portion of the casing enclosing the barrier tubes.

3. A stop joint for fluid filled cables comprising a pair of insulated conductors each having a hollow core, a separately maintained body of fluid insulation in each of the cores, a connector for the conductor ends comprising a member fitted to each of the conductors, each member having an outwardly opening port communicating with a conductor core, and a means for electrically and mechanically uniting the members, pairs of concentric cylinders of hard dense insulating material, each pair enclosing an end of an insulated conductor, channels between each pair of cylinders communicating with a port at one end, means preventing the passage of liquid from one conductor core to the other, a casing for the cylinders having end chambers with which the outer ends of the channels are in free communication, concentric barrier tubes in spaced ,irelation surrounding the connector and adjacent' ends of the insulated conductors, and a fluid lling for the part of the casing enclosing the barrier tubes.

4. An article of manufacture for cable joints comprising a pair of preformed cylinders, each made of wrapped dense insulating material and a binder, and arranged in telescopic relation and so maintained by mutual frictional engagement, both ends of the inner cylinder containing conducting material arranged to define stress cones diverging from the bore of the cylinder to the periphery thereof, a channel for fluid formed between the cylinders, a metallic casing element surrounding the outer end of the inner cylinder and pressure fitted thereto, a part of the casing and cylinder defining a chamber communicating with the channel, a second metallic casing element secured to the first near one end thereof and tightly fitted over an end of the outer cylinder to prevent the passage of fluid into the channel and chamber, the cylinders and casing elements forming a unitary structure applicable as such to a cable end.

5. A stop joint for Iiuid filled cables comprising a pair of conductors having hollow cores, factory applied insulation on the conductors having tapered surfaces in spaced relation to the adjacent conductor ends, a separately maintained body of uid insulation in each of the cores, a metallic connector part for each conductor, a winding of tape insulation covering the tapered surface of each conductor insulation, a metallic covering for a part of the tapered surface of the factory insulation to control the electrical gradient in that region, a pair of concentric insulating cylinders enclosing an end of each conductor and the tape winding thereon, each inner cylinder containing conducting material at its inner end forming a continuation of one of the metallic coverings in electrical contact with the metal connector to form a shield, concentric barrier tubes surrounding the connector and the major portion of the length of the cylinders, a casing surrounding the cylinders and tubes, and a lling of liquid insulation for the casing.

6. In a stop joint for hollow core uid filled cables, a connector part having a collar and a screw-threaded extension, a pair of preformed telescopic snugly tted cylinders of insulation surrounding a cable end, the inner cylinder being internally supported at one end by the collar, a nut mounted on the extension having a radially disposed face engaging an end of the inner cylinder and also forming an inside support for the outer cylinder, a channel for uid between the cylinders, a radial port extending through the inner cylinder into the channel, and a supporting casing part for the outer ends of the cylinders containing a chamber with which the outer end of the channel communicates.

'7. An article of manufacture for a part of a uid stop joint for cables comprising a pair of preformed cylinders of hard dense insulating material arranged in snug tting telescopic relation, the outer cylinder being shorter than the inner cylinder and defining a shoulder, a channel formed in the inner cylinder of considerable length and small cross-sectional area, a casing having parts of different diameters with a shoulder between, the part of smaller diameter surrounding the outer end of the inner cylinder and that of larger diameter engaging the outer cylinder, and a packing located at the end of the outer cylinder and between it and the casing shoulder, the cylinders being rigidly fitted into the casing parts to form a unitary structure therewith.

8. A stop joint for iiuid filled cables having a connector part, a collar, a screw-threaded extension, a nut on the extension, a pair of preformed cylinders of dense insulation tted one inside of the other with a fluid conveying channel between, the inner cylinder being supported from the inside by the collar and the outer cylinder being supported from the inside by the peripheral surface of the nut, a radial port for uid in the inner cylinder opening into the channel, and a packing located between a side surface of the nut and an end of the'inner cylinder and held against radial expansion by the inner wall of the outer cylinder.

9. A stop joint for hollow core cables comprising connector means for the conductors, pairs of preformed cylinders of insulation, those of each pair being in telescopic relation between which fluid is permitted to flow, an end casing part initially and permanently secured to the outer ends of both cylinders of each pair, the cylinders of each pair enclosing a conductor end and engaging the connector means in a manner to prevent iow of iiuid from one cable to another, each pair of cylinders and a casing part forming a unitary structure and assembled in the joint as such, a series of concentric tubular barriers surrounding the central part of the joint and extending from the ends of the joint to points beyond the center thereof, the adjacent ends of the tubes being in overlapping relation, a central casing for the joint attached at its ends to the said end casing parts, and a filling of liquid insulation for the part of the casing containing the tubes.

10. In a cable joint, conductors arranged end to end, factory applied insulation on each of the conductors which isl cut away to form a pair of opposed cones, the latter being in spaced relation to the conductor end, electrical conducting means applied to one of the cone surfaces to form a stress cone, a covering of wrapped on insulating tape filling the space defined by the cones having a diameter substantially equal to that of the factory insulation, a preformed cylinder of dense insulating material for each conductor having parallel walls surrounding the factory insulation andthe winding of tape, the inner end of the cylinder being metalized to form a continuation of the stress cone, metallic sheaths for the insulated conductors, connector means electrically uniting the conductors and also supporting the inner ends of the cylinders, and a metallic chamber casing comprising end portions jointed to the sheaths, each end portion and a cylinder being united so as to form a unitary structure and applied as such over a cable end, and a central portion connecting the end portions and with them forming a complete enclosure for the joint, the chamber containing insulating fluid.

11. In a cable joint, conductors arranged end to end, each having a fluid lled hollow core, factory applied insulation on each of the conductors which is cut away in spaced relation to the end of the conductor to form a coned shaped surface diverging from the conductor toward the center of the joint, electrical conducting means covering the surface to form a stress cone, a covering of wrapped on insulating tape for the stress cone which fills the space defined thereby to substantially the same diameter as that of the factory insulation, a pair of telescoped cylinders made of dense insulating material surrounding the factory insulation and the winding of tape on each conductor, a conduit of restricted cross-sectional area located between the cylinders of each pair of cylinders and extending lengthwise thereof, said conduit communicating with the core of a conductor, connector means uniting the conductors and also engaging and acting as supports for the inner ends of the cylinders, and

with them preventing free flow of fluid between a conductor core and the joint casing, a chambered joint casing comprising end portions in each of which is located and secured the outerl ends of a pair of cylinders to form a unitary structure and a central portion united with the end portions to complete the casing, and a filling of insulation for the chamber.

12. In a cable joint, insulated metallic sheathed hollow core conductors, a filling of insulating fluid for each of the cores, a connector means attached to the conductors for electrically uniting them and preventing the fiow of fluid from one core to the other, preformed cylinders of insulating material arranged in fixed telescopic relation surrounding an insulated end of each of the conductors, a fluid containing channel 1ocated between the respective cylinders and communicating at its inner end with the core of a conductor, a metallic casing comprising end portions sealed one to each metallic sheath, each portion having a chamber at its outer end communicating with the channel, the cylinders being permanently secured in the end portions to form unitary structures, a fitting carried by each end portion through which fluid may flow into and from the chamber, and a central portion sealed at its outer ends to the adjacent end portions for connecting them to form a complete enclosure for the joint.

13. In a high tension cable joint, a conductor, factory applied insulation thereon which is removed near an end thereof to form a pair of cones with their small ends adjacent, a metal covering for one of the cones, a body of tape wrapped over the cones and the metal covering to a diameter substantially equal to that of the original factory insulation, a preformed cylinder of dense insulation having high dielectric strength surrounding the body of tape and also the adjacent portions of the factory insulation, conducting material incorporated in an end of the cylinder and defining an outwardly diverglng cone which in effect forms a continuation of the metal covered cone of the factory applied insulation, a metal sheath for the insulated conductor, and an enclosing metal casing which is sealed to the sheath.

14. In a joint for high tension cables, conductors, factory applied insulation on each of the conductors, a portion of which is removed to form an end shoulder and expose a short length of conductor, and a second portion also removed to define a conical surface longitudinally displaced from the shoulder, a stress cone surrounding the conical surface and mounted thereon, a connector member for each conductor having a collar and socket to receive the exposed length of conductor, a body of tape wrapped around each socket and filling the space between the shoulder and collar and having a diameter approximating that of the collar, a second body of tape covering the stress cone and having a diameter approximating that of the factory insulation, a preformed cylinder of hard dense insulating material coveringa portion of the factory insulation and also the bodies of tape, a means carried by a connector member engaging the wall of the cylinder at its inner end for supporting-it, and a chamber enclosing a casing for the joint containing insulating fluid comprising central and end portions, each of the end portions surrounding and engaging the outer end of a cylinder for supporting it.

15. 'I'he method of connecting high potential insulated sheathed conductors which comprises cutting away the factory applied insulation on each of the conductors in spaced relation to the end thereof in a manner to denne a cone, removing the factory applied insulation at the adjacent ends of the conductors to expose the metal conductors, securing connecting means to the conductors to unite them, applying a metal covering to each cone of insulation nearest the connecting means, covering the cutaway portions of the insulation of both conductors with insulating tapes to approximately the diameter of the factory applied insulation, applying insulating cylinders having metalized ends over the insulating tapes with the metalized portions forming continuations of the metal coverings on the cone of the factory applied insulations. applying a covering of insulation over the connector means, enclosing the joint thus formed with a metallic casing, and securing the ends of the casing to the sheaths of the conductors.

16. The method of connecting high potential insulated metal sheathed conductors which comprises cutting away the factory applied insulation on each of the conductors in a region located in spaced relation to the respective ends thereof to a depth to expose the conductors and form double cones with their small ends adjacent each other, wrapping a thin metallic covering over the cones nearest to the ends of the conductors, wrapping the coned surfaces and the metallic coverings with insulating tapes to the approximate diameter of the factory applied insulation, applying cylinders of insulation having metalized ends over the insulating tapes with the metalized ends forming continuations of the metallic coverings, cutting away the insulation adjacent the ends of the conductors to expose them, applying connecting means to the conductor ends for electrically uniting them, applying insulation over the connecting means, surrounding the central part of the joint thus formed with cylinders of insulation, enclosing the parts in a metallic casing, and securing the casing to the sheaths of the conductors.

17. In a cable joint, a conductor, factory applied insulation thereon, a portion of which is removed to form a conical surface, a metallic covering for the conical surface forming a stress cone, a cylinder of hard dense insulating material surrounding the insulation on the conductor and also the stress cone, and metallic material arranged to define a cone incorporated in the end of the cylinder immediately surrounding the stress cone and positioned to form a continuation thereof.

18. In a cable joint, a conductor, factory applied insulation thereon, a portion of which is removed to form a conical surface, a metallic covering for the conical surface forming a stress cone, a cylinder of hard dense insulating material closely surrounding the insulation on the conductor and also the stress cone, and metallic material incorporated in both ends of the cylinder arranged to define cones, that in the outer end diverging outwardly from the factory applied insulation rargl/that on the inner end immediately surrounding the stress cone and positioned to form a continuation thereof.

LESTER L. PHILLIPS.