GB2277208A

GB2277208A - Insulated cable connector

Info

Publication number: GB2277208A
Application number: GB9406971A
Authority: GB
Inventors: John Kitching; Mark Lyndon Gledhill; John Ramsden
Original assignee: Sicame Electrical Developments Ltd
Current assignee: Sicame Electrical Developments Ltd
Priority date: 1993-04-15
Filing date: 1994-04-08
Publication date: 1994-10-19
Anticipated expiration: 2014-04-08
Also published as: GB9406971D0; GB9308515D0; HK1000180A1; GB2277208B

Abstract

A connector for at least two cables, the cores 20, 22 of which are typically provided to carry electricity supplies to residential and business premises, is formed of at least two clamping members (2, 4, figures 1, 2) the same having electrically insulated outer surfaces to allow the connection of cables using the connector when the cables are still live. There is provided a contact means having at least one contact face which is toothed or is substantially V-shaped 28 and/or has a knife edge to improve the formation of the contact with the cable core. The conductive contacts 10 are mounted in electrically insulating holders. <IMAGE>

Description

Improvements Relating to Cable Connectors This invention relates to electrical connectors for the connection of underground cables typically but not exclusively used to carry low voltage electricity supplies.

The connectors can be used for the connection of two cable ends or to allow a branch or service cable to be connected to the main supply cable.

The cables which are connected may be connected for different purposes and services and consequently may be of the same size or may be of different sizes. For example the cable cores may range in size from the order of 4 mm2 in cross section to 300 mm2 but all the cores are provided with insulation covering. Cores of the cable are formed of electric conducting material such as copper or aluminium and the cores may be circular, quadrant or sector shaped and can be of solid or stranded electric conducting material.

To cover these variations, conventional connectors are required to be provided in different types and sizes with connection means for specific cable sizes. To fit the cables to the connectors the majority of same require the removal of the insulation from around the cable cores, followed by the screw clamping of the connector teeth to the exposed cable core. This is inconvenient in that the action of exposing the core properly requires skill and an additional operation and furthermore it is difficult to remove the insulation when the connector is to be coupled to a cable intermediate to the ends of the cable.

The applicants have identified the above problem and their co-pending Application No 9208603.2 discloses a connector comprising two members formed from electrically conductive material, each having teeth formed therein which, when the teeth are tightened into position, serve to penetrate the core insulating material surrounding the core and hence contact the core to form an electrical connection between the cable cores.

While this connection removes the requirement for the insulation to be removed the invention does not address several other problems and disadvantages which are known.

At present when cables are to be connected there is a need for the cables which are to be connected to be dead i.e. not carrying an electrical supply. While this provides the necessary safety for the operators connecting the cables and prevents their exposure to live cables, considerable disruption is caused to the electricity supply and hence to the electricity consumer. As the suppliers of electricity become increasingly accountable for failures in the power supply so each disruption in the supply can be costly to the supplier.

Furthermore, due to the conventional connectors used and the requirement to remove core insulation material and such like from the cables, the jointing of cables is regarded as a skilled job and hence both the manpower and level of skill required is expensive to the electricity supplier.

The aim of the present invention is to provide a connector for the electrical connection of the cores of cables which provides a means for connecting said cables without the need to disrupt the electricity supply through said cables and with minimal alteration of the cables.

The present invention in a first aspect provides a connector for use in connecting the cores of at least two cables for carrying an electricity supply underground, said connector comprising at least two members adapted to be moved toward each other to hold the cables therebetween and including electrically connected contact means to contact the cable cores wherein the external surfaces of the connector are electrically insulated to allow the connector to be used irrespective of whether or not the cables are carrying electricity at the instant of connection.

In one embodiment at least one of the members is provided with electrically connected contact means having at least one contact face formed thereon such that when the connector members are moved together to hold and connect the cables the contact means are moved onto the cables such that the contact faces thereon achieve electrical contact with the cores of the cable. Typically contact means are provided in each of the connector members and the same are arranged such that a contact face thereon contacts opposing sides of each cable held between the members.

In one embodiment the contact face is formed of a plurality of teeth, the points of which are arranged to face the cable held in the connector. Alternatively the contact face is provided with edges which define a substantially V-shape.

Another preferred feature of the contact faces is that the edges thereof are provided with a knife edge and particularly when the contact face is V-shaped.

Preferably the connector includes contact means in the form of an insert of electrically conducting material insertable into location means provided in the members. Typically each insert incudes two contact faces, a first contact face for contact with a first cable core and a second contact face for contact with a second cable core.

In one embodiment the connector is provided with clamping means in the form of a clamping bolt provided with a head designed to shear off once a certain torque is achieved hence maintaining the connector members at the required clamping torque and maintaining the teeth in electrical connection with the cable cores.

Typically the members of the connector are formed of high mechanical resistance insulating material or a highly resistant insulating material and the material has required dielectric properties to ensure that the connector members can be safely handled when the cable cores to be connected are live. One such material is a glass fibre reinforced nylon which is used to manufacture the members and allow location of the contact means therein.

Typically the connector is provided to connect the cables lying in a side-by-side arrangement.

In one embodiment the connector is used to connect a mains cable to a service or branch cable and the part of the connector securing and connecting the service or branch cable is provided with a cap portion to ensure that the end of the cable core is not exposed. Typically the cap portion is slidingly engageable into slots in the connector to blank off the ends of the connector ports which are not used, and hence maintain the complete insulation of the connector and prevent exposure of the live cores.

Preferably said connector, when fitted underground is encapsulated in a resinous material to ensure that the connection is waterproof and/or protected from mechanical damage in addition to being insulated.

In a further aspect of the invention there is provided a contact means for use in a connector to contact at least one cable core said contact means having at least one contact face in the form of a substantially V- shape.

In one embodiment there is provided a contact means for use in an electrical connector for connecting the cores of at least two electricity cables, said contact means in the form of an insert formed of electrically conductive material wherein the insert has at least two contact faces such that when a first contact face contacts a first cable core and a second contact face contacts a second cable core, electrical connection of the cable cores is achieved.

Preferably the contact means has contact faces wherein the edges of the contact faces are knife edged.

Specific embodiments of the aspects of the invention will now be described with reference to the accompanying drawings wherein; Figure 1 illustrates a plan view of one of the connector members; Figure 2 illustrates an end elevation of the second of the connector members; Figure 3 illustrates the members of Figures 1 and 2 combined to form the connector; Figure 4 is a detailed cross sectional elevation on Line A-A of Figure 1; Figure 5 is a plan view of the connector of the invention shown connecting two cables; Figure 6 is an elevation of an insert for the connector in a second embodiment; and Figure 7 is an elevation of the inserts of Figure 6 held in the connector and approaching engagement with cable cores of different cross sectional shapes.

Referring firstly to Figures 1 and 2 there are shown the two members 2 and 4 which, when combined, form the connector of the invention. The first member 2 is provided with four cable reception beds 6 each of said beds formed into a shape to allow location of the cable cores therein. Each bed is also provided with a contact means 8 of electrically conductive material and said contact means is provided with at least one contact face 10 positioned to protrude above the cable reception bed 6 in which it is located. In this embodiment the contact face is formed of teeth 11 as shown in greater detail in Figure 2 where the second member 4 is additionally provided with a clamping bolt 12 for clamping the member 4 to the member 2, the bolt being threaded and screwed into the threaded hole 14 in member 2. Each of said contact means 8 are electrically connected or provided with two integral contact faces for contact with adjacent cables such that when the cable cores are engaged by the resepctive faces 10 electrical connection between the cable cores is achieved.

Figure 3 shows the two members 2 and 4 forming a connector of the invention. The cable cores, when connected, run in the plane as indicated by arrow 16. Also shown is a cap portion 18 which can be slidably fitted to the connector ends to cover a port in the connector if the connector is used to connect a cable end to a main cable, hence preventing the end of the cable from being accessible to tools, fingers or foreign matter when the same is live. The cap also acts to maintain the complete insulation of the connector.

Figure 4 is a sectional view which shows in greater detail the contact means 8, in a first embodiment, fitted into the insulating material which forms the members 2 and 4. The teeth 11 of the contact face 10 can be seen to protrude from the bed so that when the cable lies therein the teeth can penetrate the insulating material surrounding the cable core and come into contact with the core when the two members are tightened together.

Figure 5 shows a connection between a mains cable 20 to which is connected a branch cable 22, said connection provided by the connector of the invention shown in plan. The mains cable 20 passes through the connector as shown and in doing so is brought into contact with the cable reception beds 6.

The end of the branch cable 22 is placed adjacent the cable 20 in the connector, the open part of the connector covered by the cap portion 18.

To use the connector of the invention to connect cable cores as shown in Figure 5, the two members 2 and 4 are loosely held together by the bolt 12 but with sufficient space between them to allow cables 20, 22 to be placed in the respective reception beds 6 in member 2. When in position, the clamping bolt 12 is tightened to bring the cable reception beds 6 provided on the top member 4 into contact with the respective cables. The clamping bolt continues to be tightened such that the contact faces 10 provided on the contact means 8 in the beds 6 penetrate the insulation 24 which surrounds the cores 26 of the cables. Finally the clamping bolt is tightened to such an extent that the contact faces, in the form of teeth 11 in this embodiment, pierce the insulation and come into contact with the cores of the respective cables and hence, via the electrical connections between the teeth, the cables 20 and 22 are electrically connected. The head of the clamping bolt 12 is designed to shear off at a predesignated torque level and so the connector members 2 and 4 are maintained with sufficient torque to maintain the electrical connection between the cable cores.

As an alternative to having contact faces 10 in the form of teeth 11 the faces may be V shaped such that they are positioned in relation to the core reception beds to allow the cables lying therein to lie between the arms of the V.

Furthermore the edges of the contact faces, in whichever embodiment, but most effectively when the same are V-shaped, are knife edged such that as the contact faces are brought into contact with the cable the knife edges slice into the insulation to contact with the cable core irrespective of the size or shape of the cross section of the cable.

Figures 6 and 7 illustrate a contact means 8 in the form of an insert 26 which can be used in cable core connectors as, for example, described above. In this embodiment the insert 26 includes two contact faces 10, one contact face for each cable core to be connected, and electrical connection between the cables is achieved by contact of the faces with respective cores of the cables. Furthermore, the contact face 10A is shown in a V-shape 26 with the edges 28 having a convex shape and provided with knife edges. This shape of contact face allows a wide variety of cables having various cross sectional areas or shapes to be more reliably contacted without the need to vary the size or dimensions of the connector as is conventionally the case, and a greater proportion of the core to be contacted than with a contact face 10 formed of teeth 11 as shown in face 10B. An additional feature is that the knife edges allow the face, when contacting the cable insulation, to more easily slice into the insulation hence allowing quicker and improved electrical contact with the cable cores.

As the connector of the invention is fully insulated and there is no need to physically handle the core of the cables it is completely feasible and safe for the connector to be used to connect cables when at least one of the cables i.e.

mains cable 20, is live. No breaking of the insulation material of the cable takes place except within the confines of the insulated connector by the teeth 10 and so electricity supplies can be maintained whilst the connection is performed. This represents a considerable advance in both safety and savings in costs and disruption to electricity supplies.

The connector of the invention, incorporating an insert having two contact faces allows the connector to be used for the connection of cables of different dimensions and cross sectional geometries and allows the connection to be achieved while at least one of the cable cores is live with the insulation of the connector ensuring the safety of the operator. The connector allows the electricity supply to be maintained during cable connection work.

Claims

1. A connector for use in connecting the cores of at least two cables for carrying an electricity supply underground, said connector comprising at least two members adapted to be moved toward each other to hold the cables therebetween and including electrically connected contact means to contact the cable cores wherein the external surfaces of the connector are electrically insulated to allow the connector to be used irrespective of whether or not the cables are carrying electricity at the instant of connection.

2. A connector according to Claim 1 wherein at least one of the members is provided with electrically connected contact means having at least one contact face formed thereon such that when the connector members are moved together to hold and connect the cables the contact means are moved onto the cables such that the contact faces thereon achieve electrical contact with the cores of the cable.

3. A connector according to claim 2 wherein contact means are provided in each of the connector members and the same are arranged such that the contact faces thereon contact opposing sides of each cable held between the members.

4. A connector according to claim 2 or 3 wherein the contact face comprises a plurality of teeth, the points of which are arranged to face the cables held in the connector.

5. A connector according to either of claims 2 or 3 wherein the edges of the contact face define a substantially V-shape.

6. A connector as in any of claims 2-5 wherein the edges of the contact faces are knife edged.

7. A connector according to any of the preceding claims wherein the contact means is in the form of an insert of electrically conducting material insertable into location means provided in the members.

8. A connector according to claim 7 wherein each insert incudes two contact faces, a first contact face for contact with a first cable core and a second contact face for contact with a second cable core.

9. A connector according to any preceding claim wherein the members of the connector are moved together to hold the cables therebetween and to bring the contact faces into contact with the cores of the same by tightening a screw clamping means acting on both members.

10. A connector according to claim 9 wherein the screw clamping means is provided with a head portion designed to shear off when a predetermined clamping force is reached.

11. A connector according to any preceding claim wherein the connector members are formed of highly resistant electrically insulating material.

12. A connector according to claim 11 wherein the insulating material is also mechanically resistant.

13. A connector according to claims 11 or 12 wherein the connector members are formed of glass fibre reinforced nylon material.

14. A connector as hereinbefore described with reference to the accompanying drawings.

15. A contact means for use in an electrical connector for contacting the core of at least one electricity cable, said contact means having at least one contact face in the form of a substantially V-shape.

16. A contact means according to Claim 15 wherein the contact means is provided in the form of an insert of electrically conductive material wherein the insert has at least two contact faces such that when a first contact face contacts a first cable core and a second contact face contacts a second cable core, electrical connection of the cable cores is achieved.

17. A contact means according to claims 15 or 16 wherein the edges of the contact faces are knife edged.

18. A contact means according to any of claims 15 - 17 with reference to Figures 6 and 7.