DE3444195A1 - ENCLOSED CABLE SPLICING AND METHOD FOR THEIR PRODUCTION - Google Patents

Description

The invention relates to forming cable splice closures .

A core connecting cable leading away from a main office for laying underground or above ground contains a core with a variety of possible up to 3600 Pairs of individually insulated conductors.

When laying the cable, it is sometimes necessary to cut the cables end-to-end to be connected to each other in order to achieve a required cable length. Usually in such a case the Conductors from the two cables are spliced by removing the end portions of the material surrounding the core, i.e., the cable shields or sheaths and the cable jackets so that the cores protrude from this material by bringing the cable cores tightly together and then connecting the conductor ends while holding them between the cable sheaths and jackets. The connections are then sealed and a splice closure placed over the area of the splices to fill the gaps bridged between the shells and still extends a bit over the respective shells.

The problem with this common practice is that inexplicably some moisture paths are left behind and some splices are known to develop as a result of exposure to moisture fail. A possible explanation for this phenomenon is believed to be that if steps are taken to prevent moisture ingress, moisture is still along the way the inside of the cable passes through. Once the moisture reaches a splice, each one becomes imperfectly sealed Connections between conductors allow moisture to enter and the splice to fail.

The present invention provides a method of forming a splice closure and a splice closure even where the problem mentioned is at least

is at least partially circumvented in such a way that the number of splice points failing due to the ingress of moisture in the case of end-to-end splices Long-distance connection cables is kept as low as possible. The inventive method relates to the removal of Material from the two cable ends, which surrounds the cores, the spreading of the conductor in the radial direction over the cable diameter addition and bringing the two cable ends together, the ends of the material surrounding the cores being sufficient come close together to allow sufficient conductor lengths to extend axially of the interconnected conductors of a cable can be placed, with the splice points each over the material surrounding the core. The one with each other connected conductors are then individually sealed, and the entire cable splice is terminated with an encapsulation, which extends over and surrounds the material surrounding the cores on each cable, plus each conductor splice surrounds.

Accordingly, the invention provides a method for forming an encapsulated splice area between two cable ends following steps:

the material surrounding the core from the end portions of two cables is removed so that end portions of the material surrounding the cores arise, as well as core areas of the cable that extend a certain distance over the Protruding end portions of the surrounding material,

the conductors of the areas are twisted so that they protrude radially outward from the cables,

the cable end sections and the sections of material surrounding the cores become closer together brought and arranged axially to one another,

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the conductors of one end of the cable are electrically connected to those of the other end of the cable, and so on Ladder splices formed, and

while each conductor splice is laid on an end portion of material surrounding the core, the associated conductors traverse the end section and extend to the respective cable cores, each conductor splice is individually enclosed in sealing material and axially encapsulates the end sections of material surrounding the cores to cover the conductor splices and to seal against the ingress of fluid.

In the process according to the invention, they are within the respective Sealing material lying conductor splices through the end portions of the material surrounding the cores during encapsulation supported so that a sealing effect going under pressure can take place and achieve an effective seal will. After encapsulation, the splices are sealed apart and the seal is also opposite effective in the core area.

Sealing material is preferably used to enclose the splices in the form of warm softening (thermoplastic) sealing tape as overlapping and superimposed winding intended. In order to best encase the splice points, material surrounding the core is made around the respective end section first windings provided, then the splice points are arranged separately from each other on these first windings, second windings overlapping and superimposed over the splice points and wound over the first windings, and the encapsulation is then applied so that it surrounds the windings, the encapsulation temperature being sufficient high heGt to soften the sealing tape and make it a single one To connect ground in order to enclose each individual splice tightly. This way the first and second

Windings combined into an integral unit.

Preferably, the encapsulation is formed with a moldable plastic material surrounding the end portions of the core Material is molded. After the encapsulation has cooled down, it shrinks towards the softened sealing tape, which is thereby expanded resulting pressure leaves the interconnected unitary mass of ribbon material in intimate fluid-tight contact with it come every splice. This is because of the particular effectiveness of the seal formed around each individual splice any moisture present in the core area between the cables or surrounding the encapsulation is effectively applied thereto prevented from reaching the respective splice points.

It follows that the basic goal of encapsulation is to make a seal of the sealing material around each To form splice, while it is considered less important that encapsulation be with the surface of the surrounding cores Material of each end region achieved a seal. Preferably, however, such a seal is also created, and for this purpose the encapsulation material should preferably be aligned with the surface of the material surrounding the cores be compatible that a connection is created by the heat of formation.

Alternatively, the encapsulation is made from a heat-shrinkable material which creates the heat to soften the sealing tape.

The invention also provides an arrangement of two end-to-end abutting one another Long-distance connection cables in which the conductors of each cable core are individually connected to a conductor of the other cable core Electrically connected to form a conductor splice, the conductors of each splice extend outwardly from the cores and in the axial direction along the material of a cable surrounding the respective core, around the splice point radially outside of the material surrounding the core, each

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Splice is individually sealed by sealing material, and an encapsulation extends over the two cable ends so that that it surrounds the sealed splices and end portions of the material surrounding the cores.

An exemplary embodiment of the invention is based on the following the drawing explained in more detail; in this shows:

1 shows a side view of the respective ends of two cables prepared for splicing,

Fig. 2 is a sectional view of the two cable ends during an execution step of Splicing process,

3 side views of the cable ends in subsequent and 4 stages of the splicing process,

FIG. 5 shows sectional views of the cable ends during and 6 final stages of the splicing process, and FIG

7 shows an enlarged sectional illustration through a Part of the completed splice assembly of the cable ends.

In Fig. 2 two cables 12 and 14 are shown, which by electrical Connect each individual conductor 16 or 18 from the cable cores 20 or 22 to an individual conductor of the other cable should be connected to each other. In order to enable the formation of splice points of the conductors, the one surrounding the core is used Material of each end of the cable, i.e. a metal sheath or screen 24 and polymeric jacket material 26 removed to expose a portion of the core 20 or 22 protruding beyond the end portions of the cladding 26. As is explained in more detail, it is necessary in the procedure according to the invention described below, the interconnected Head to lay so that they are axially over one of the

two sheaths 26 extend so that their splices are outside of the respective cables and are supported by the associated jacket. In order for this process to be followed, the length of the conductor protruding from the jacket and shield of each cable should be sufficient. In the case described here, in which two underbody remote connection cables with 400 conductor pairs each are to be connected, it has been found that each cable shield and jacket should be removed sufficiently that a protruding portion of the cable core of approx. 300 mm is exposed.

The conductors of each core end are then twisted outwardly so that they are in all radial directions from the respective cables stand out and a separation of the conductor pairs is achieved. Through this process it is then possible to essentially remove the cable ends in axial alignment with more closely spaced material surrounding the cores than would be the case would if the cores were left in the state shown in FIG. The cable ends are used in this particular structure actually brought so far together that the shells 24 have a distance of about 75 mm. One made of metal Conductor 28 is then placed bridging the gap between the metal screens 24 and attached to the screens in the usual way, so that they are electrically connected to each other. This is the process state represented by FIG. 2.

Electrical conductor pairs of one cable are then electrically spliced to pairs of the other cable. It will be like this accomplished that each individual conductor of each pair in a known manner, for example through the use of connectors 30, with a individual conductors of the other pair is spliced. Since the conductor pairs from the cable ends were laid radially outwards, the conductor splices can then conveniently be formed at the ends of the outwardly protruding conductors, the connectors 30 can be arranged outside the cable. Fig. 2 shows two conductor connection points in this position.

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In this condition it is necessary to keep any splice created by the conductor ends and associated connectors 30 within to hold a sealant in order to secure the splice points against moisture penetrating from the outside in a first stage.

In order to initially secure the splice points, first windings 31 are made of a heat-softening sealing tape covering and wound on top of each other on the end portion of each cable jacket 26 so as to create a layer 32 of sealing tape, as shown in FIG. The sealing tape used in the embodiment described is an ethylene-propylene rubber sealing tape. The spliced pairs of conductors are then placed on each of the two end sections of the cable sheaths 26 in such a way that that the splice points come to rest on the first winding layer 32. As can be seen from FIG. 3, it follows from this laying up that one conductor of each spliced pair goes from its own cable core to the other cable is enough and lies on the layer 32 of the other cable. The other conductor of each pair spliced together is wrapped around the The screen and sheath of its own cable laid around so that it points axially along this cable in the direction from which he comes. In a preferred embodiment, as shown in this embodiment, it is convenient to use the Lay up splices in some orderly fashion so as to have as many splices as possible on each layer 32 can be placed relatively little space. One particular type of arrangement of practical value is that shown in FIG. As shown, the splices are laid on each layer 32 in circumferentially extending tapes 34, the splices of each ribbon being spaced from the adjacent splice. To get through the Allow conductors between the splices of one ribbon to reach the splice in other ribbons can, it is advantageous if the splice points of adjacent tapes are staggered, as shown in FIG. 3.

The splices are then made with a second winding 35 the said tape covered. These windings are applied directly to layer 3? placed so that they both the layer 32 as also touch the splice points. These second windings are also placed overlapping one another, so that one Layer 36 covering layer 32 results, as shown in FIGS. 4, 5 and 6 shown. The layer 36 is then surrounded by another layer 38 of a material that, upon softening of the material in layers 32 and 36 does not soften, like is described in more detail. This layer 38 is provided to prevent the material of layers 32 and 36 from being displaced from their respective position surrounding the splice points, if heat and pressure are applied in further process steps will. The layer 38 shown in Figures 5, 6 and 7 can be made of any suitable material, for example each other Covering wrapped wrapping made of fiberglass tape, or, as in this version, made of vinyl tape.

The arrangement formed in this way is then enclosed by an encapsulation, which is created by a low pressure molding process. With this process, mold pressure values are below 6.9 bar (100 lbs./sq. In.) Is used, and preferably these pressures are in the range of 1.0 bar (15 lbs./sq. In.) Or less. The material of the encapsulation is preferably selected with a view to its compatibility with the jacket material of the cables. In the case described, in which the jacket material is based on polyethylene, the encapsulation should consist of a moldable Ethyl acrylic acid, made from ionomer resins, a polyethylene or an ethyl vinyl acetate. Examples of such materials those compatible with polyethylene are, for example, those from Dow Chemical of Canada Limited under the product numbers 459, 455 or 435 ethyl acrylic acids sold, those of Dupont under the brand names "Surlyn" 152 and "Surlyn" Ionomeric resins sold in 1702 and that sold by Dupont of Canada Limited under product number 3180. The connection between ethyl acrylic acid and polyethylene depends on the proportion of acrylic acid in the encapsulation

material from.

In the embodiment described, in which a seal between the polyethylene jacket and the encapsulation material is sought, as well as a seal between the ethylene-propylene rubber band existing layers 32 and 36, it is preferable to use polyethylene as the molding material. It has The tape material in layers 32 and 36 has been shown to readily bond to polyethylene when the tape is applied is softened by warmth. Thus, under the molding conditions as they exist here, sufficient heat is applied to the tape in the Heat layers 32 and 36 so as to bond with both the polyethylene of the shell and the polyethylene of the encapsulation connect to.

The partially completed connection between the cable ends 12 and 14, as shown in FIGS. 4 and 5, is then inserted into the FIG Fig. 6 shown low-pressure mold 40 introduced and finally assembled there. This mold contains mold halves 42. Only one of these mold halves is shown since the illustration in FIG. 6 is cut along the parting plane of the mold. Malleable Material is extruded through inlet 44 into mold cavity 46 to encapsulate with the polyethylene material to shape. The polyethylene flows through the entire mold and fills the cavity, and also fills any existing between the conductors Gaps between the spaced ends of the jacket 26, as shown in FIG. 6. As soon as the The mold is filled with the molding material, the extrusion process is stopped by using a switching device 48, the switching device 48 operating automatically when the mold is filled. This switching device is detailed in the CA patent application SN 395,552 of February 4, 1982 (L. J. Charlebois et al "Molding of Plastics Articles"). As shown in Fig. 6, the switching device includes a limit switch 50 which is located in a passage 52 at a distance from the mold cavity. Of the Passage 52 is bridged, but prevented, by the molten material within the mold cavity during filling

the surface tension of the material and the small cross-sectional size of the passage 52 allows the molten material to penetrate through the passage so that the switch is not actuated will. As soon as the mold is filled, the internal mold pressure increases slightly to e.g. 1.0 bar (15 lbs./sq.in.), And that molten material can now flow into the passage 52 and activate the switch which then stops the extruder. The melted one Material is at a temperature sufficient to allow heat to penetrate through vinyl tape layer 38 and the Warming layers 32 and 36 and allowing them to soften. This softening of the ethylene-propylene rubber band allows the windings and layers to flow together so that the ethylene-propylene material becomes a unitary mass that tightly surrounds and encloses each splice. After the molten material has cooled down The ethylene-propylene rubber also cools and hardens the end. The cooling of the encapsulation 54 releases a compressive force the ethylene-propylene material act through the vinyl material, and the ethylene-propylene material shrinks so that it is intimate Comes into contact with the surfaces of the splices. Since the splices are actually on the outside of the jacket 26 the jacket forms a support for the ethylene-propylene tape, so that the shrinkage takes place effectively and a fluid seal for the otherwise exposed conductor wires and the Connector 30 forms. The fluid seal also exists between the ends of the encapsulation and the polyethylene material of the jacket as the jacket will also soften and blend with the encapsulation united. In addition, prior to encapsulation, the layer 38 made of vinyl tape was placed in such a way that the end sections of the Layers 32 and 36 protrude slightly from the ends of layer 38. There is a protruding length of 12.7 mm (0.5 in) sufficient. This detail can be seen in FIGS. 5, 6 and 7. So at each end of the vinyl tape touches the polyethylene encapsulates the ethylene-propylene material and creates a bond between it and the polyethylene, creating another sealing point is created.

The inventive method described above provides an effective seal in the end-to-end connection of Cable. Placing the splice points on the cable jacket ensures that the jacket material cools the ethylene-propylene tape squeezed together so that each splice is effectively sealed. This seal is made even more by the seals existing between the encapsulation and the jacket and between the encapsulation and the ends of the ethylene-propylene tape improved. It is also ensured that any moisture present in the cores of the cables can damage the splice points itself cannot reach it, as this moisture cannot penetrate the seals between the encapsulation and the ethylene-propylene rubber band in layers 32 and 36, and also not by sealing the integral rubber mass surrounding each splice can penetrate. Tests carried out with cable ends connected in this way have shown that after the encapsulated area has been subjected to a cyclic thermal load, a reliable seal in each Case was created that did not allow moisture to penetrate the exposed wires or the connectors 30 either Splice caused failure.

Claims (12)

Claims 1. Method of forming an encapsulated splice area that the material surrounding the core is removed from the end portions of two cables (12, 14) to end portions of the material surrounding the cores to create and cable core areas (20, 22), which a protrude to a certain extent beyond the end sections of surrounding material, that the conductors of the areas are turned so that they protrude radially outward from the cables, that the cable end portions and the end portions of the material surrounding the cores are brought closer together 2 - MANlTZ · FINSTERWALD - HEYN · MORGAN ■ 8000 MUNICH 22 · ROBERT-KOCH-STRASSE 1 ■ TEL. (089) 224211 · TELEX 05-29672 F'ATMF HANNS-, If) Rf? ROTFRMI) ND 7000 STUTTGART 50 (BAD CANNSTATT) SEELBERGSTR. 23/25 ■ TEL- (0711) 567261 34U195 and are arranged axially to one another that conductor (16) of a cable end (12) with which (18) of the other end of the cable (14) are electrically connected to form conductor splices, and that while each conductor splice is located on an end portion of core-surrounding material is that the associated conductors extend over the end section to the respective cable cores, each conductor splice individually encased in sealing material and axially over the end sections of the material surrounding the cores is encapsulated to cover the splices and be fluid-tight to seal. 2. The method according to claim 1, characterized characterized in that the splice points in a heat-softenable sealing tape (31, 35) as sealing material be included and that the sealing tape is softened to cause it to be connected to an integral whole by the influence of the heating achieved during the encapsulation. 3. The method according to claim 2, characterized characterized in that encapsulating by molding an encapsulation of plastic material around the splice area is carried out, wherein the heat from the plastic material present in the molten state, the sealing tape for connecting caused to form an integral whole, and that the encapsulation is cooled in order to shrink it onto the softened sealing tape, the resulting pressure in the bonded and softened unitary mass of tape around each splice intimate and fluid-tight sealing contact with each splice caused. 4. The method according to any one of claims 1 to 3, characterized in that the material of the radially outer Areas of the material surrounding the cores with the encapsulation material is compatible, and that these materials during of shaping mix and connect with each other, 5. The method according to any one of the preceding claims, characterized characterized in that the heat-softenable sealing tape is compatible with the encapsulating material that the Sealing tape is wrapped with a holding material that is not softenable by heat at the mold temperature, that the holding material holds the sealing tape in place after softening and that the protruding sealing tape during molding with the Encapsulation material connects. 6. The method according to any one of the preceding claims, characterized characterized in that the radially outer regions of the material surrounding the cores and the encapsulation material consist of polyethylene or contain polyethylene, and that the sealing tape is an ethylene-propylene-rubber tape. 7. The method according to any one of the preceding claims, characterized in that the sealing tape first in each other overlapping and superposed windings provided around an end portion of the core surrounding material is that the splices are placed at spaced locations on the first windings, that second Windings overlapping and touching one another over the splices and wound the first windings and that the first and second windings are softened in order to connect them together into the integral whole. 8. The method according to claim 7, characterized characterized in that the splices on the first turns in a plurality of circumferential turns extending rings (34) axially spaced around the windings are arranged with the splices in each ring being circumferentially spaced, 9. The method according to claim 8, characterized
marked that the splices in the adjacent Bearded rings are arranged offset from one another in the circumferential direction will, 10. Arrangement of two long-distance connection cables arranged end to end, in which conductors of each cable are each electrically connected to a conductor of the other cable to each forming a conductor splice, characterized in that the conductors (16, 18) each Splice extending outwardly from the cores (20, 22) and axially along the material (24, 26) surrounding the cores extending one of the cables (12, 14) to position the splice radially outward from the material surrounding the cores, that each splice is individually sealed by sealing material (32, 36) and that there is an encapsulation (54) over the two Cable ends extended so as to surround the sealed splices and end portions of the material surrounding the cores. 11. Arrangement according to claim 10, characterized characterized in that the splices on an end portion of the material surrounding the cores are in a plurality axially spaced apart from circumferentially extending rings (34), the splices each Ring have a distance in the circumferential direction. 12. Arrangement according to claim 11, characterized characterized in that the splice points of adjacent rings are offset from one another in the circumferential direction.