GB2543792A - Cable jointing - Google Patents

Abstract

A method of joining cables comprises wrapping self-fusing tape (30, Fig 1C, 40a, Fig 1D, 40b, Fig 1F) around the cable or wire ends (1, 2, 3, Fig 1A) to insulate and seal the cable to form a joint, and contacting a flexible sheet or tape (60, Fig 1G) with either a resin or water, to activate a water activated component, to form a composite material. The self-fusing tape is then encompassed by the flexible sheet or tape such that the resin or water activated component binds the matrix component and flexible sheet or tape to form a rigid outer shell to substantially surround the joint.

Description

CABLE JOINTING

Field of the Invention

The present invention relates to a kit, method and joint for jointing cables or wires. Background A "cable" as used herein is intended to be broadly interpreted as referring to a length of insulated conductor (which may for example be a single strand of wire or a multi-strand wire). It will be appreciated that in many applications a plurality of insulated conductors (which may be individually insulated) are grouped together (and provided within a common outer insulation and/or amour) within a single cable.

Joining (or "splicing") of wires or cables is often required as a result of damage to lines. Such repairs are often required to be carried out in situ and should ideally provide a repair which will be sufficiently durable to last the remaining lifetime of the cable. The repair may for example need to provide environmental sealing/protection, particularly for example when repairing underground cables.

Although there are many types of jointing methods, direct burial applications are dominated by resin filled cast joints. Conductors are spliced, then placed at equal distance within a plastic mould before being solidly encased in a liquid resin that hardens to form an insulating layer and environmental protection equivalent to IP67. However, the substances used in resin cast moulding are often harmful and/or carcinogenic and, therefore, there are a number of environmental and safety concerns associated with their use. Due to market pressures, over time the range of quality of resin joints are varied. High failure rates give impetus to the search for alternative solutions.

In 2007 extensive testing using a high grade silicone self fusing (or self-amalgamating tape) -LLFA Compression Tape - was undertaken by the Applicant, which demonstrated an alternative jointing method that met the international standards for direct burial cable jointing. Even though the sealing capability of this jointing method allows for movement in the cable without failure, there has been reluctance to adopt such a method for use as an alternative to resin cast jointing, as resin is mechanically stronger.

There is therefore a need for a method of providing a joint which can be used in a number of different environments, including for example above and below ground applications. There is also a need for a kit for forming a joint which gives rise to reduced environmental and safety concerns, and creates a more flexible seal while being mechanically robust.. There is also a need for a kit for forming a joint which can be readily used without requiring the use of a highly skilled operative. Embodiments of the invention seek to address at least some of these needs.

Summary of the Invention

According to a first aspect of the present invention, there is provided a jointing kit for joining cables, the kit comprising: self-fusing tape; and a composite material for use in encompassing the self-fusing tape, in which the composite material comprises a flexible sheet or tape and a matrix component for binding the flexible sheet or tape, the matrix material comprising a resin or water activated matrix component.

According to a second aspect, the present invention provides a method of jointing cables, the method comprising: wrapping self-fusing tape around the cable or wire ends to insulate and seal the cable to form a joint; contacting a flexible sheet or tape with either a resin or water, to activate a water activated component, to form a composite material; and encompassing the self-fusing tape with the flexible sheet or tape such that the resin or water activated component binds the matrix component and flexible sheet or tape to form an outer shell with the flexible sheet or tape to substantially surround the joint.

The flexible sheet or tape may comprise a woven material (such as for example fibre glass material). Thus, the flexible tape or sheet may comprise a woven tape. The flexible sheet or tape may be made from fiberglass or carbon fibre weave or equivalent.

The matrix component may be epoxy resin. Accordingly the kit may further comprise a supply of epoxy resin.

Alternatively, the matrix component may be a water soluble and/or water activated component. For example, the matrix may be polyurethane.

The flexible sheet or tape may be pre-impregnated with the matrix material or a component of the matrix material. Thus, the composite may be formed in-situ by activation of the matrix material during the procedure to encompass the self-fusing silicone tape. For example, the composite material may be arranged such that on contact with water the matrix component causes the layers of composite material to bind to form an outer shell, preferably a hard outer shell with the flexible sheet or tape.

After the resin or water-activated matrix sets with the flexible sheet or tape it forms an outer shell. The outer shell may be considered as mechanically strong as a resin cast joint. Thus, embodiments of the invention may provide the flexibility of a silicone taped joint with the mechanical benefits of a resin joint. The outer shell protects and isolates the underlying self-fusing tape from the environment. As a result, the hard outer shell increases the lifetime of the joint between the free ends of the wires or cables. Preferably, the lifetime of the joint formed by the kit of the present invention is approximately greater than 30 years.

The kit of the present invention protects against imperfect application of the self-fusing tape. The formation of the hard outer shell on and/or within the composite material ensures that the self-fusing tape is held securely in position even when particles are present underneath the self-fusing tape. The kit of the present invention therefore significantly reduces the risk of the joint failing.

In particular, due to the self fusing nature of the tape, the applicants have recognised that joint failure of existing repairs typically occurs when the tape lifts (i.e. in a generally radial direction) for example due to contamination between layers because the tape once wound around the cable with an appropriate overlap will resist any circumferential sliding between the layers due to self-fusion. Thus, an advantage of the provision of a protective/overlying composite layer, in accordance with embodiments of the invention, is that it may physically prevent any such lifting ensuring a more reliable joint/repair even if some contamination may be present due to user error.

Advantageously, the composite material, and the formation of the outer shell, may further increase the environmental and water seal protection to provide a more secure and effective joint.

Preferably, the composite material comprises woven material (such as for example fibre glass or carbon fibre material). Thus, the flexible tape or sheet may comprise a woven tape. Preferably, the composite material comprises between 40% and 70% by weight, of the composite material (and it will be appreciated that the remainder of the composite material is the matrix).

The resin or water activated component is preferably a polymeric water soluble and/or water activated component. For example, the resin or water activated component may be a polyurethane water soluble and/or water activated component. Preferably, the water soluble and/or water activated component comprises 1,3-propanediol, 2-ethyl-2-(hydroxymethyl), polymer with bis(isocyanatomethyl)benzene.

Preferably, the self-fusing tape is a silicone tape. The self-fusing tape can preferably be applied to the joining ends of the cables without requiring any additional attachment means. The self-fusing tape is preferably suitable for use on any low voltage, medium voltage or high voltage applications. The self-fusing tape may for example be the Applicants' commercially available LLFA (RTM) Tape.

The joining kit preferably further comprises an accessory pack for use in making a joint. For example the accessory pack may comprise mechanical connector. For example the mechanical connector may be one or more of a crimp connector or a butt splice crimp connector. In some embodiments a selection of dedicated accessory packs may be supplied with a jointing kit according to the invention. A plurality of accessory packs may be provided corresponding to a predetermined selection of common repair or jointing tasks. In some embodiments each dedicated accessory pack may correspond to a commonly required type and/or size of cable joint (for example providing the expected additional components expected to be required for the particular joint).

Thus, the method or kit of the invention may enable a modular approach to the provision of jointing kits. Depending upon the intended usage scenario either a plurality of accessory packs may be used with a supply of self-fusing tape and composite material or pre-packaged quantities of self-fusing tape and composite material (typically combining both elements in a single pack) may be provided. For example, the modular system may comprise self-fusing tape and composite material prepacked in a combined fixed quantity unit. As such a kit for a required repair may be formed (as/when required) from a selected quantity of prepack units and a corresponding accessory pack. For example, the accessory pack may provide an indication of the required amount of self-fusing tape and/or composite required for the associated joint (thus, a jointing kit may readily be assembled as required from a supply of accessory packs, self-fusing tape and composite material).

Preferably, the at least one mechanical connector is shaped and dimensioned to receive and connect to the corresponding wire or cable. The joining kit may comprise mechanical connectors having a range of dimensions for connecting to appropriately dimensioned wires or cables.

The, or each, joining kit may comprise at least one (for example a set) of mechanical connectors for use with a predetermined wire or cable size. For example, a kit or kits may be provided for a range of wire dimensions having a wire size in the range of between 0.5 mm2and500 mm2.

The cables may be steel wire armour cables. Accordingly, the kit may further comprise a woven wire mesh for replacing the cable shielding during repair. Additionally the kit may comprise a plurality of amour rings.

The kit may further comprise a protective film material, such as for example a film material capable of being arranged in use to substantially encompass and to exert a compressive force on the underlying composite material. The protective film material may be in tape form. The protective film material may remain in contact with the composite material for a predetermined time period, such as for example up to 5 minutes, to exert a compressive force on the underlying composite material during the formation of the hard outer shell.

According to a further aspect, the present invention provides a joint comprising: an end of at least one first cable portion; an end of at least one second cable portion; self-fusing tape substantially encompassing a connection between the ends of the at least one first and second cable portions; and a composite material comprising a flexible sheet or tape and a matrix component binding the flexible sheet or tape; in which the composite material forms an outer shell (which may be substantially rigid once fully cured) around the self-fusing tape by activation of a resin or water activated matrix component during formation of the joint.

The joint may be a straight joint or a branched joint.

In particular the kit, method and joint may be for use in the repair of wires or cables. An embodiment of the present invention will now be described in detail with reference to the following accompanying Figures.

Brief Description of Figures

FigureslA-lH are sequential photographs of the method of forming a joint in an armoured cable using a kit according to one embodiment of the present invention.

Detailed Description

The kits of the present invention are used to form joints between wires or cables. An example will now be described in which the cable is a steel wire armour cable. The example cable has three separate insulated strands 1, 2, 3 within a single armoured and insulated sheath. It will be appreciated that the application of the invention is not limited to any particular cable configuration.

With reference to Figure 1A, in order to form a joint between at least two cables the ends 10, 20 of each cable need to first be prepared. The joint may typically be to repair a damaged cable section or could be a new connection. The skilled person will appreciate that the initial preparation and connection of the cable strands may be carried out in a conventional manner with the individual strands 1, 2, 3 being connected together by any convenient means. For example, crimp connectors 4, 5, 6 may be used to connected the joining ends of the respective cables 1, 2, 3 (although other suitable mechanical connectors may also be used depending upon the cable and joint type).

As shown in Figures IB and 1C, a section of self-fusing tape 30 is then wrapped around each connector 4, 5, 6. The self-fusing tape is preferably LLFA (RTM) tape, available from the applicant GTG Europe Limited. The self-fusing tape is preferably silicone tape and can be applied to the joining ends of the wires or cables without requiring any additional attachment means. This provides a layer which reinstates (in the case of a repair) or provides (in the case of a new connection) the required insulation between the individual strands 1,2,3 of the cable.

With reference to Figures ID, after each connector has been spliced and suitably insulated with self-fusing tape, all of the connectors are joined together by wrapping the entire connection in a full wrap 40a of self-fusing tape.

In order to provide its maximum predetermined fusion ability, the self-fusing tape is applied whilst stretched to provide a predetermined tension to the tape. The tape is preferably wrapped around the connector(s) to form at least two layers. The self-fusing tape is wrapped around the joint in an overlapping manner (preferably at least in a half lap fashion) to ensure good bonding.

In the case of an armoured cable as shown in the example, after an initial wrap 40a in selffusing tape the wire armour is then re-established along the length of the joint (as shown in Figure IE). The wire armour (in the form of a metallic mesh) 50 may be connected (both electrically and physically) to the exposed amour of the cable ends 10, 20 by means of an amour ring 51, 52, at each end (or any other suitable attachment means). A further layer of self-fusing tape 40b is then wrapped around the joint entirely covering the joint including both amour rings 51, 52 as shown in Figure IF. As discussed above with respect to the first layer 40a, the self-fusing tape is stretched as required in order to provide sufficient fusion around the joint. Thus, the self-fusing tape fully replaces the original insulating layer of the cable and fully seals the connection.

On application, the self-fusing tape forms a compressive sheath around the joining ends of the wires or cables. The self-fusing tape is durable, resilient and is easily applied to the joining ends of the wires. The self-fusing tape is arranged in use to insulate and seal the joining ends of the wires or cables where high and low temperature stability is required. The self-fusing tape forms a waterproof layer which protects the joint from moisture and weather. The self-fusing tape also acts as a UV shield.

Once the initial jointing and protection using the self-fusing tape is complete, the preimpregnated fibre glass composite tape is placed in a suitable container and exposed to water. The fibre glass tape may be a woven fibre glass tape and may be pre-impregnated with 1,2-propanediol, 2-ethyl-2-(hydroxymethyl), polymer with bis-(isocyanatomethyl)benzene.

The fibre glass composite material remains in contact with the water for the required period. The wet/activated fibre glass composite tape 60 is then contacted with and wrapped around the self-fusing tape of the joint (as shown in Figure 1G). The wet/activated fibre glass composite material substantially encompasses the self-fusing tape of the joint.

Once the composite layer is complete, a protective film tape 70 may then be temporarily wrapped around the fibre glass composite material wrapped joint as shown in Figure 1H. The protective stretch film tape is wrapped around to provide a protective layer which substantially encompasses and exerts a compressive force on the fibre glass composite material wrapped joint. The protective film tape provides additional protection and additional compressive force to the joint during formation of the hard outer shell. It is however to be understood that the kit of the present invention may be used to form the joint with or without the additional protective film tape.

The fibre glass composite material wrapped joint is then left for a predetermined period of time. In this example, the fibre glass composite material wrapped joint is left for about 5 minutes. After five minutes, the 1,2-propanediol, 2-ethyl-2-(hydroxymethyl), polymer with bis-(isocyanatomethyl)benzene has formed a hard outer shell substantially encompassing and extending along the length of the fibre glass composite material wrapped joint. It will of course be appreciated that the time required for the joint to set may depend upon several factors such as the type of composite materials and the type of cable or connection being formed

Once the composite has set, the optional protective film tape is removed from the joint and leaves the composite material having formed a hard, outer shell of glass fibre composite material. The hard, outer shell exerts a compressive force on the underlying silicone tape. As a result, the hard, outer shell prevents lifting of the silicone tape from the joint and therefore helps to minimising the risk of the joint failing as a result of movement and/or lifting of the silicone tape.

The method of the invention can be used for multiple joints comprising for example multiple cable ends of differing sizes. As such, it will be appreciated that a kit can readily be provided comprises self-fusing tape and flexible fabric material which may be suitable for a variety of jointing requirements. The kit of embodiments of the present invention is therefore not specific to a particular type of joint. Embodiments of the present invention provide a cost effective kit for forming joints between cables or wires. The kit of embodiments of the present invention does not produce any hazardous products and therefore does not give rise to any health concerns for the operator or environmental concerns. An advantage of the invention is that a kit comprising a supply of self-fusing tape and a supply of composite material may be provided which then allows a user to carry out a great range of repairs. An accessory kit could be provided in a pre-packaged kit with the additional components (for example connectors and armour replacement) required for a particular repair. The kit could have a predetermined amount of self-fusing tape and/or composite or may include instructions indicating how much should be taken from a separate supply.

Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

For example, whilst the described embodiment utilises a woven glass fibre which is preimpregnated with a water-activated matrix component it will be appreciated that other matrix components may be suitable. For example two part resins (for example epoxy based resin systems) are available which may suitable for provision in a kit form and mixed when required.

Claims (22)

Claims

1. A jointing kit for joining a plurality of wires or cables, the kit comprising: self-fusing tape; and a composite material for use in encompassing the self-fusing tape, in which the composite material comprises a flexible sheet or tape and a matrix component for binding the flexible sheet or tape, the matrix component comprising a resin or water activated matrix component.

2. A jointing kit as claimed in claim 1, in which the flexible sheet or tape is a woven material.

3. A jointing kit as claimed in claim 2, in which the flexible sheet or tape is a fibre glass or carbon fibre material.

4. A jointing kit as claimed in any preceding claim, wherein the flexible sheet or tape is be pre-impregnated with the matrix material or a component for forming the matrix material.

5. A jointing kit as claimed in any preceding claim, wherein the matric component is a polymeric water soluble and/or water activated substance.

6. A jointing kit as claimed in any preceding claim, in which the matrix component is a polyurethane resin.

7. A jointing kit as claimed in any one of claims 1 to 6, in which the matrix component comprises 1,3-propanediol, 2-ethyl-2-(hydroxymethyl), polymer with bis(isocyanatomethyl)benzene.

8. A jointing kit as claimed in any preceding claim, wherein the kit further comprises an accessory pack including additional components required for forming a joint.

9. A jointing kit as claimed in claim 8, wherein a plurality of accessory packs are provided corresponding to a predetermined selection of common repair or jointing tasks.

10. A jointing kit as claimed in claim 9, wherein each accessory pack may be used with a common supply of self-fusing tape and composite material.

11. A jointing kit as claimed in claim 9 or 10, wherein the jointing kit comprises a modular system comprising self-fusing tape and composite material prepacked in a combined fixed quantity unit, such that a required kit may be formed from a selected quantity of prepack units and a corresponding accessory pack.

12. A jointing kit as claimed in any of claims 8 to 11, wherein the accessory pack comprises at least one mechanical cable connector.

13. A jointing kit as claimed in any of claims 8 to 12, wherein the accessory pack further comprises a cable shielding component.

14. A jointing kit as claimed in any preceding claim, further comprising a protective film material.

15. A joint comprising: an end of at least one first cable portion; an end of at least one second cable portion; self-fusing tape substantially encompassing a connection between the ends of the at least one first and second cable portions; and a composite material comprising a flexible sheet or tape and a matrix component binding the flexible sheet or tape; and in which the composite material forms a rigid outer shell around the selffusing tape by activation of a resin or water activated matrix component during formation of the joint.

16. A joint as claimed in claim 15, further comprising at least one connector arranged to receive the ends of the at least one first and second cable portions.

17. A method of jointing cables comprising: wrapping self-fusing tape around the cable or wire ends to insulate and seal the cable to form a joint; contacting a flexible sheet or tape with either a resin or water, to activate a water activated component, to form a composite material; and encompassing the self-fusing tape with the flexible sheet or tape such that the resin or water activated component binds the matrix component and flexible sheet or tape to form an outer shell with the flexible sheet or tape to substantially surround the joint.

18. A method of jointing cables as claimed in claim 17, wherein the method further comprises selecting an accessory kit specific to the joint being formed from a predetermined selection of kits.

19. A method of jointing cables as claimed in claim 18, wherein the method further comprises selecting a quantity of self-fusing tape and composite material in corresponding to the accessory kit selected.

20. A joining kit substantially as herein described with reference to the accompanying figures.

21. A joint substantially as herein described with reference to the accompanying figures.

22. A method substantially as herein described with reference to the accompanying figures.