GB2487428A

GB2487428A - Biodegradable cable joint shell

Info

Publication number: GB2487428A
Application number: GB1101154.1A
Authority: GB
Inventors: Gary Barnett
Original assignee: Tyco Electronics UK Ltd
Current assignee: Tyco Electronics UK Ltd
Priority date: 2011-01-24
Filing date: 2011-01-24
Publication date: 2012-07-25
Anticipated expiration: 2031-01-24
Also published as: GB2487428B; GB201101154D0

Abstract

A cable joint shell formed of biodegradable material (e.g. card, paper pulp) holds resin 135 around a cable joint while the resin 135 in cured. The resin 135 insulates and protects the cable joint from an external environment. The cable joint may be suitable for burial in the ground, wherein the biodegradable material degrades in the ground after the cable has been laid. The cable joint shell may be formed of a waterproof material and may be formed by upper and lower halves 121, 122, the upper half 121 having; an aperture 130 for pouring resin 135 into the cable joint shell, and a cap to plug the aperture 130. The cable joint shell may be used with cables 101-103 that handle voltages in the range 240V 36kV. Also included is a method of forming a cable joint that comprises electrically joining at least two cables 101-103, surrounding the electrical joint with a cable joint shell, and pouring resin 135 into the cable joint shell to surround the electrical joint, wherein the cable joint shell is formed of a bio-degradable material.

Description

A CABLE JOINT SHELL FOR A CABLE JOINT

The present invention relates to a cable joint, and in particular to a cable joint shell used as part of a cable joint.

A known cable joint for low and medium voltage underground cables comprises an electrical joint between two cables, and a compound encasing the electrical joint to insulate and mechanically protect it. The compound is typically a 2 or 3 part resin system, and is held within a plastic cable joint shell surrounding the electrical joint. During the making of the joint, the resin is poured into the cable joint shell, and the cable joint shell holds the resin in position whilst it cures.

Such cable joints are typically buried in the ground, either permanently, or until the end of the life of the cable when the cable joint is removed and disposed of in a land-fill site. It is therefore an aim of the invention to provide a more environmentally-friendly cable joint.

The inventor has recognised that the functions of insulating and mechanically protecting the joint in the ground may be sufficiently fulfilled by the resin without the presence of the cable joint shell. However, the cable joint shell can be difficult to remove from the resin after curing since the resin sticks to it.

According to a first aspect of the invention, there is provided a cable joint shell for holding resin around a cable joint whilst the resin is cured, the cable joint shell being formed of a bio-degradable material.

Owing to the invention the cable joint shell can be made from a biodegradable material that degrades in the ground after the cable has been laid.

This can reduce the amount of non-biodegradable material that is present in the ground and that needs to be disposed of after the useful life of the cable.

Advantageously, the cable joint shell may be formed of a waterproof material. The waterproofing can enable use of the cable joint shell for creating cable joints outside in wet weather conditions. The waterproofing is sufficient for the cable joint shell to substantially maintain its shape for at least 10 hours during the presence of water, giving sufficient time for the resin to cure.

Furthermore, the cable joint shell may comprise a card or paper pulp that is treated with additives to provide waterproofing. The card or paper pulp may biodegrade after burial of the cable into the ground, leaving the resin behind to fulfil the functions of insulating the electrical joint from the surrounding environment and mechanically protecting the cable.

The card or paper pulp may be recycled card or paper pulp to further improve the environmental friendliness of the cable joint shell. Suitable moulding processes that incorporate additives into card or paper pulp for waterproofing are known to those skilled in the art. The waterproofing may for example be achieved by adding wax or starch to the pulp before it is moulded into the final shape.

Typical examples of pulp moulded products with waterproofing additives are disposable bowls/bottles used in hospitals for collecting bodily fluids.

The cable joint may be used for joining low and medium voltage underground cables, for example cables that handle voltages in the range of 240V -36kV.

The resin encases the electrical joint to insulate and mechanically protect the electrical joint during the life of the cable, which may be over 50 years, or even over lOoyears.

Each one of the two cables comprises at least one conductor for joining to at least one conductor of the other of the two cables. In some embodiments the cable joint may comprise a plurality of cables and the cable joint shell may enclose a plurality of electrical joints between different conductors of the plurality of cables.

The term biodegradable material means that the material is capable of decaying through the actions of living organisms such as bacteria or decaying through a natural process such as sunlight or water. The timescales over which the biodegradable material decomposes depends greatly on the environmental conditions, although typically the material starts to break down within five years of being buried.

According to a second aspect of the invention, there is provided a cable joint insulation kit comprising a cable joint shell according to the first aspect, and a resin for pouring into the cable joint shell.

According to a third aspect of the invention there is provided a cable joint suitable for burial into the ground, comprising an electrical joint between two cables; a cable joint shell according to the first aspect that surrounds the electrical joint; and a resin around the electrical joint, the resin filling the cable joint shell.

According to a fourth aspect of the invention there is provided a method of forming a cable joint, comprising electrically joining at least two cables, surrounding the electrical joint with a cable joint shell, and pouring resin into the cable joint shell to surround the electrical joint, wherein the cable joint shell is formed of a bio-degradable material.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. I a -I c show a schematic diagrams of a cable joint according to an embodiment of the invention; and Fig.2 shows a flow diagram of a method for forming a cable joint according to an embodiment of the invention.

The schematic diagram of Fig 1 a shows two cables consisting of a first cable 101 and a second cable 102. Each cable has four conductors that are joined together with connector blocks 111, 112, 113, and 114, although alternatively other numbers of conductors may be present within the cables.

A third cable 103 having four conductors is also present, and the four conductors of the third cable 103 are joined to the corresponding four cables of the first and second cables at the connector blocks 111, 112, 113, and 114.

Alternatively, the third cable may not be present, or additional cables may be present.

The joint between the cables 101, 102, 103 is housed within a joint shell 120. The joint shell 120 has upper and lower halves 121 and 122, as will now be described with reference to Fig.1 b.

The upper and lower halves 121 and 122 are formed by moulding them from recycled card/paper pulp (for example, as is used for various packaging systems and for medical applications). The process includes the addition of additives at the moulding stage to give a degree of water-proofing (for example, to render the halves water-proof for at least 10 hours) but still allow the halves product to degrade over a period of several months.

The waterproofing helps protect the joint shell from outside weather conditions whilst an engineer installs the joint, but once installed the joint shell will slowly degrade completely to leave only the hardened resin.

The two halves of the joint shell are placed around the cable joint and clipped together by clips 125. The upper half 121 has an opening or aperture 130 for pouring resin 135 into the joint shell. The resin 135 surrounds the electrical joints and insulates and protects them. The halves 121 and 122 enclose the cable joint sufficiently well to prevent excessive leakage of the resin out of the shell during the curing of the resin. The clips 125 are formed of a material such as for example metal or plastic, and may optionally be removed before burying the cable in the ground.

Once the joint shell 120 has been filled with resin 135, a cap 140 may optionally be applied to the opening 130 of the upper joint shell 121. The cap 140 may prevent excessive leakage of the resin from the joint shell when the orientation of the joint shell is changed, for example so that the cable can be into the ground before the resin has finished curing.

The embodiment of Fig.la-lc shows a joint shell formed in upper and lower halves, although alternate arrangements for the biodegradable joint shell will also be apparent to those skilled in the art. For example, the joint shell could be formed by left and right side halves, each half forming half of the aperture (e.g. each half having a semi-circle cut-away). Then, the left and right side halves could be formed by using the same mould. Alternatively, the joint shell may be formed in more than two parts, or the joint shell may be formed in a single part.

A cable joint insulation kit (not shown in Figs) comprises the joint shell halves 121 and 122, and the resin 135. The kit may be supplied to persons laying cables into the ground for protecting cable joints from damage. The kit preferably includes the clips 125, and may also include other items such as cable connectors for making the electrical joints between the conductors and insulation shrouds.

is The flow diagram of Fig.2 shows a method 200 for forming a cable joint according to an embodiment of the invention. The method 200 comprises a step 210 of electrically joining two cables, a step 220 of surrounding the electrical joint with a cable joint shell formed of biodegradable material, and a step 230 of pouring resin into the cable joint shell to encase the electrical joint.

The step 210 of electrically joining two cables comprises joining the conductors of the cables together using known techniques, for example by means of connector blocks. The cable joint shell is formed of biodegradable material such as recycled paper or card pulp, and is attached around the cable joint in step 220.

Finally, resin is poured into the cable joint shell to encase the electrical joint in step 230. Resins suitable for encasing the electrical joints will be apparent to those skilled in the art, for example resins that are already used in known cable joints that have non-biodegradable cable joint shells.

The scope of the invention is defined by the appended independent claim(s). Further features appearing in the dependent claims and the description are only optional and may or may not be implemented in various embodiments of the invention which will be apparent to those skilled in the art.

Claims

CLAIMS1. A cable joint shell for holding resin around a cable joint whilst the resin is cured, the cable joint shell being formed of a biodegradable material.
2. The cable joint shell of claim 1, wherein the cable joint shell is formed of a waterproof material.
3. The cable joint shell of claims 1 or 2, wherein the cable joint shell comprises a card or paper pulp that is treated with additives to provide waterproofing.
4. The cable joint shell of claims 1, 2, or 3, wherein the cable joint shell is adapted for use with cables that handle voltages in the range of 240V -36kV.
5. A cable joint shell according to any preceding claim, wherein the cable joint shell is formed by an upper half and a lower half, the upper half having an aperture for pouring resin into the cable joint shell.
6. A cable joint shell according to any preceding claim, wherein the cable joint shell further comprises a cap for plugging an aperture of the cable joint shell.
7. A cable joint insulation kit comprising a cable joint shell according to any preceding claim, and a resin for pouring into the cable joint shell.
8. A cable joint suitable for burial into the ground, comprising: -an electrical joint between two cables; -a cable joint shell according to any of claims I to 6 and surrounding the electrical joint; and -a resin around the electrical joint, the resin filling the cable joint shell.
9. A method of forming a cable joint, comprising electrically joining at least two cables, surrounding the electrical joint with a cable joint shell, and pouring resin into the cable joint shell to surround the electrical joint, wherein the cable joint shell is formed of a bio-degradable material.
I 0. A cable joint shell substantially as described herein or as shown in the accompanying drawings.Amendments to the claims have been filed as followsCLAIMS1. A cable joint shell for holding resin around a cable joint whilst the resin is cured, the cable joint shell being formed of a biodegradable material and comprising a card or paper pulp that is treated with additives to provide waterproofing.2. The cable joint shell of claim 1, wherein the cable joint shell is formed of a waterproof material.3. The cable joint shell of claim I or 2, wherein the cable joint shell is adapted for use with cables that handle voltages in the range of 240V 36kV.4. A cable joint shell according to any preceding claim, wherein the cable joint shell is formed by an upper half and a lower half, the upper half having an aperture for pouring resin into the cable joint shell. c\J r5. A cable joint shell according to any preceding claim, wherein the cable joint shell further comprises a cap for plugging an aperture of the cable joint shell.o 6. A cable joint insulation kit comprising a cable joint shell according to any preceding claim, and a resin for pouring into the cable joint shell.7. A cable joint suitable for burial into the ground, comprising: -an electrical joint between two cables; -a cable joint shell according to any of claims I to 5 and surrounding the electrical joint; and -a resin around the electrical joint, the resin filling the cable joint shell.8. A cable joint shell substantially as described herein or as shown in the accompanying drawings