Cable connections

Abstract

A plurality of telecommunications connections are installed in a distribution network by connecting a series of distribution points using a multicore cable comprising a plurality of cores having a common enclosure, some of the cores carrying fiber tubes into which optical fiber may later be introduced, and other cores carrying an electrical power supply. One or more cores may be diverted from a longer cable run to serve a local distribution point by rupturing a web connecting the core to the rest of the cable, thus allowing the remaining cores to be uninterrupted at the point of divergence. An alternative embodiment intended for underground use provides for apertures to be opened in a protective sheath to expose the individual cores required to be diverted to a local distribution point.

Claims

1. A method of installing a plurality of telecommunications connections in a distribution network comprising: connecting a series of distribution points to an exchange using a multicore cable connected to the exchange and comprising a plurality of cores having a common enclosure, at least one of the cores being a hollow tube through which optical fiber can be inserted and at least one other core being arranged to carry an electrical power supply, and arranged such that the enclosure may be disrupted over part of a length of the enclosure; connecting each of a series of distribution points passed by the multicore cable to one or more of the cores by disrupting the enclosure at a divergence location close to the respective distribution point to allow a length of the or each core that is to be connected to the distribution point to be separated from the multicore cable core at the divergence point; cutting the diverging core or cores to a length suitable to reach the distribution point; and connecting the diverging core or cores to the distribution point.

2. A method according to claim 1, wherein at least one of the cores of the multicore cable carries a wire pair for telecommunications.

3. A method according to claim 1, wherein the at least one other core being arranged to carry an electrical power supply is connected to voltage converters at the distribution points.

4. A method according to claim 1, wherein the cable comprises a number of cores connected by frangible webs which are integral with at least an outer encapsulation of each core, and in which the webs are ruptured over a length of the cable close to one of the termination points in order to split one or more cores away from the cable such that the one or more cores may be connected to the termination point.

5. A method according to claim 4, wherein the multicore cable is attached to a run of suspension points passing a number of distribution points, and at a suspension point close to each individual distribution point one or more cores are separated from the multicore cable by rupturing the frangible webs to form a branch to the respective distribution point.

6. A method according to claim 1, wherein the individual cores are enclosed in a sheath through which apertures may be opened to gain access to the individual cores within.

7. A method according to claim 6, wherein weaknesses are provided in the sheath at intervals along a length of the sheath to allow the apertures to be created.

8. A method according to claim 6, wherein an aperture is opened in the sheath and a length of one or more cores is withdrawn through the aperture to be connected to a distribution point in the vicinity of the aperture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the disclosure will now be described, by way of example and with reference to the drawings, in which:

(2) FIG. 1 is a schematic depiction of a first prior art arrangement.

(3) FIG. 2 is a schematic depiction of a second prior art arrangement.

(4) FIG. 3 is a schematic depiction of a section of cable according to an embodiment of the disclosure, intended for subterranean installation.

(5) FIG. 4 is a schematic depiction of a distribution network using cables configured according to an embodiment of the disclosure.

(6) FIG. 5 is a schematic depiction of a cross section of a cable according to an embodiment of the disclosure, intended for overhead installation.

(7) FIG. 6 is a schematic depiction of a section of the cable of FIG. 5, in use.

(8) FIG. 7 is a schematic depiction of an alternative embodiment.

(9) FIG. 8 is a schematic depiction of an alternative embodiment.

DETAILED DESCRIPTION

(10) In the prior art arrangement shown in FIG. 1, a number of distribution points 20, 21, 22, 23, 24, 25 are each served by a respective cable 30, 31, 32, 33, 34, 35 connecting the distribution point to an exchange (switch) 1. As shown, some of the distribution points 20, 21, 22 are mounted on poles 40, 41, 42, and the cables 30, 31, 32 are suspended from the poles. In particular, some poles, e.g. pole 40, support cables serving more distant distribution points 21, 22 as well as terminating a cable 30 at the distribution point 20 mounted on or near that pole.

(11) FIG. 1 also depicts an underground conduit 43 carrying a plurality of cables 33, 34, 35 each serving a respective distribution point 23, 24, 25 located within or accessible from the conduit.

(12) It will be recognized that installing a separate cable to serve each distribution point would be cumbersome. Moreover, because of changes in technology, and differing customer needs, it is often necessary to provide several types of communications connection to each distribution point, and different combinations of connections may be required at each. For example, some distribution points may require more fiber optic connections than others. Some distribution points may also require a power supply from the exchange 1. This can result in several cables being run between each distribution point and the exchange 1.

(13) FIG. 2 illustrates an alternative prior art arrangement, in which several distribution points 20, 21, 22 (or 23, 24, 25) are connected to the exchange 1 and each other by a series of lengths of multicore cable 50, 51, 52, 53, 54, 55. One length 50 of cable connects the exchange 1 to a first pole-mounted distribution point 20, and respective further lengths 51, 52 connect the first distribution point 20 to the second distribution point 21, and the second distribution point 21 to the third distribution point 22.

(14) Similarly, in the conduit system 43, one length of cable 53 connects the exchange 1 to a first distribution point 23, and respective further lengths 54, 55 connect the first distribution point 23 to the second distribution point 24, and the second distribution point 24 to the third distribution point 25.

(15) Typically cable is made in very long lengths, and it is preferable to minimize the number of joints or splices in them, in order to avoid structural weakness or electrical or optical impairment at the joints. However, in arrangements such as depicted in FIG. 2, it is necessary to install multiple short lengths of cable 50, 51, 52 (or 53, 54, 55) to reach the more remote distribution points 21, 22, 24, 25 in order to serve the other distribution points 20, 23 passed on the way. This requires the cable to be severed at each distribution point passed.

(16) The present disclosure uses a novel design of cable which avoids the problems described above. Different embodiments of such cable are configured for overhead and underground use.

(17) Referring first to FIG. 3, a section of multicore cable 8 is depicted. This comprises a number of individual cores 93, 94, 95, 96 enclosed in a protective sheath 89. Although only four cores are depicted, in practice many more may be included. Typically some of the cores 96 will carry wire pairs, either for power supply or communications, and others 93 94, 95 will be fiber tubes, through which optical fiber may be inserted after the complete end-to-end run is installed. Each core may itself carry a number of wire pairs or fiber tubes, or a combination of both.

(18) The sheath 89 is arranged such that apertures 83 (84, 85) may be opened in it at intervals along its length. The material of the sheath may be such that an aperture may be opened with a suitable cutting tool at any point along its length, or special weakened sections may be included at intervals to allow such apertures to be created. The individual cores 93, 94, 95, 96 are accessible to an operative through these apertures 84.

(19) The installation process of the subterranean cable will now be described, with reference to FIG. 3 and FIG. 4. As shown in FIG. 4, the cable 8 is first installed in the conduit 43, passing the distribution points 23, 24, 25 that are to be connected to the exchange 1. In the vicinity of each distribution point 23, 24, 25, an aperture (83, 84, 85) is opened in the sheathing material 89. The operative can then grasp a core 93 by hand or with a suitable tool, and draw a loop of the core through the aperture 83 until a length of the core 93 has been withdrawn that is sufficient to be connected to the distribution point 23. Any surplus length 98 of the core 93 can then be cut off (99). Thus a branch 93 has been formed in the multicore cable 8, without severing any of the other cores 94, 95, 96 not terminating at the distribution point.

(20) Similar branches to other distribution points 24, 25 may be created by opening further apertures 84, 85 and extracting the required cores 94, 95, as shown in FIG. 4.

(21) If required, and as shown in FIG. 4, two or more cores 95, 96 may be branched off the cable 8 through one aperture 85. In the example shown in FIG. 4, a distribution point 25 is to be powered from the exchange 1 and therefore requires an associated power input 26, capable of converting a 110V/230V supply delivered by the exchange to the voltages required by the distribution point 25 itself. The power can be delivered by connecting a power core 96 to the power input 26 associated with the distribution point 25. This core 96, together with the optical fiber core 95 connected to the distribution point 25, are both accessed through an aperture 85.

(22) Further embodiments will now be described, with reference to FIG. 4, FIG. 5, FIG. 6, FIG. 7 and FIG. 8. This embodiment is intended for overhead installation.

(23) FIG. 5 depicts a cross section of a multicore cable 6 for use in embodiments of the disclosure. This cable comprises a number of cores 60, 61, 62, 63, 64 all surrounded by a common enclosure 69. The enclosure 69 defines a plurality of lobes 60, 61, 62 63 forming individual cores, connected by integral frangible webs 70, 71, 72, 73 to a central core 64 forming a strengthening member. In this embodiment three of the cores 60, 61, 62 each contain eight wire pairs, and a fourth core contains twelve fiber tubes, but this is only illustrative and the number and structure of individual cores can be varied.

(24) This cable may be produced by a series of extrusion processes, first to generate the individual cores 60, 61, 62 63 and then, bunched together, extrude through a further extrusion die to encase the individual cores in an outer layer 69 incorporating the webs 70, 71, 72, 73. Alternatively the outer parts of the individual cores 60, 61, 62, 63 may be softened, and then deformed and adhered together to become a single outer layer incorporating the webs.

(25) FIG. 6 depicts a short section of the cable 6. As can be seen, one of the cores 60 has been partially separated from the central member 64 by tearing the web 70.

(26) The installation of the overhead cable 6 will now be described, with reference to FIG. 4. As shown in FIG. 4, the cable 6 is first connected to a number of poles 40, 41, 42. Distribution points 20, 21, 22 that are to be connected to the exchange 1 are mounted on, or close to, at least some of these poles.

(27) The core or cores 60 which are to be connected to a particular distribution point 20 are separated from the main core 64 over the distance between the required branching point 80 and a convenient point some distance further from the exchange 1this can typically be the next pole top 81and the core can then be cut to length at that point. Thus a branch 60 has been formed in the multicore cable 8, without severing any of cores 61, 62, 63 not terminating at the distribution point 20. The newly free end of the core 60 can then be connected to the distribution point 20.

(28) Similar branches to other distribution points 21, 22 may be created by peeling off the required cores 61, 62, as shown in FIG. 4.

(29) If required, and as shown in FIG. 4, two or more cores 62, 63 may be branched off the cable 6 at the same suspension point 82. In the example shown in FIG. 4, a distribution point 22 is to be powered from the exchange 1 and therefore requires an associated power input 27 capable of converting a 110V/230V supply delivered by the exchange to the voltages required by the distribution point 25 itself. The power can be delivered by connecting a power core 63 to the power input 27 associated with the distribution point 22. This core 63, together with the optical fiber core 62 connected to the distribution point 22, are separated from the central core 64 by rupturing the respective webs 73, 72.

(30) An alternative embodiment is depicted in FIG. 7, in which the cores 60, 61, 62, 63 are arranged side-by-side instead of around a central strengthening core 64, with each core connected to its neighbors by a frangible strip 70, 71, 73. The required core (e.g. core 60) can then be separated from its neighbor by tearing the respective frangible strip 70. In this embodiment, each of the cores 60, 61, 62 containing power cables also carries a wire pair 68 suitable for conventional telecommunications.

(31) A further embodiment is depicted in FIG. 8, in which each core 65, 66 comprises a single fiber tube (65) or power connection (66), each core being connected by webs 75, 76 to the central strength member 64. One of the cores 65 is shown partially separated from its neighbors in order to diverge from the main cable run to serve a nearby distribution point. A separate core 69 carries a wire pair for conventional telecommunications.

(32) These embodiments can be formed in a similar way to that described for the embodiment of FIGS. 5 and 6, by means of a suitably shaped die for the extrusion process.