GB2151086A

GB2151086A - Electrical cable tap connectors

Info

Publication number: GB2151086A
Application number: GB08329801A
Authority: GB
Inventors: Roy Philip Dent; David John Brennan
Original assignee: Hepworth Electrical Developments Ltd
Current assignee: Sicame Electrical Developments Ltd
Priority date: 1983-11-08
Filing date: 1983-11-08
Publication date: 1985-07-10
Also published as: GB8329801D0; GB2151086B

Abstract

A cable tap connector incorporates a screw-operated cable clamp. A first cable (B) is located in the bottom of a metallic channel (10) and then a spacer plate (29) is positioned over same. A second cable (T) is positioned on top of the spacer plate (29), with a clamp plate (28) resting on the top of the second cabe (T). One or two bolts (22,24) pass through a bolt plate (18) which is restrained from moving when the bolts (22,24) are tightened to press the clamp plate (28) onto the top cable (T), the top cable (T) onto the spacer plate (29), the spacer plate (29) onto the bottom cable (B). A heat-shrinkable insulating sleeve may be shrunk onto the connector, the sleeve including an internal heat sensitive adhesive which softens during heat- shrinking. <IMAGE>

Description

SPECIFICATION Improvements relating to electrical connectors This invention relates to electric connectors, being coupling devices for the electric connecting of electrical cables or wires.

Mainly, electrical connectors to which the invention relates are used for mains distribution, the connectors being used in underground location and, after being fitted to the cables to be connected, being encapsulated to seal and insulate the electrical cables so connected.

There are known various forms of electrical connectors which comprise essentially channel members in which the cables are located, and clamp members for clamping the cables to the channels and/or together, in order to establish the electrical connection. The components of the connector are electrically conductive, and typically comprise mainly aluminium extensions.

In one known form of connector, the chan nel member is of W or M configuration, being an extrusion defining two side by side channels for receiving the respective cables to be electrically connected, each channel being associated with a bolt plate carrying clamping bolts. Upon location of the cables in the channels, the bolts are tightened against the bolt plate and serve to clamp the cables in the channels. The bolt ends may react against a pressure plate or pad in each channel which pressure plate is forced on to the cable by the action of tightening the bolts.When these connectors are used to couple cables of the same size and configuration, the channels are of similar size, but when the connectors are to couple cables of different size and/or configuration, such as arises in the connection of mains cables to distribution cables, then channels of differing size and/or configuration are used.

In another known arrangement, the connector comprises a single channel member of such length as to accommodate two cables arranged in superimposed relationship which contact directly, and above the upper cable the pressure plate is located above the upper cable and against this pressure plate the connector bolts are screwed in order to force the cables into intimate contact with each other and with the channel member.

This second type of connector is usable only with certain forms of electrical cables which satisfactorily contact each other under the clamping stress, but the arrangement is unsatisfactory in the majority of cases.

The present invention seeks to provide an arrangement whereby an electrical connector has means for the effective coupling together of electrical cables located in the same channel, in an effective and novel manner.

In accordance with the present invention, an electrical connector comprises a channel member and a spacer plate of electrically conductive material, such spacer plate being of a size to fit in the channel with its plane lying transverse to the channel walls, whereby two electrical cables to be electrically connected can be located respectively above and below the spacer plate so as to be in electrical contact therewith, the connector also having clamping means for urging the top cable on to the spacer plate, the spacer plate on to the lower cable and hence the lower cable into contact with the channel member.

The clamping means may comprise a bolt or clamping plate in which one or more clamp bolts is or are carried and which is connectable to the channel so as to be restrained from movement relative to the channel in the direction of the channel walls in order to achieve firm clamping of the cables when the bolt or bolts is or are tightened. The clamping means may additionally include a pressure plate which is for location between the end or ends of the clamp bolt or bolts and the top cable.

The said pressure plate may have the surface which faces the top cable of a concave nature and with serrations thereon, for the effective electrical contact with the upper cable, whilst the said spacer plate may have its upper and lower surfaces concave and optionally serrated for the effective contact between the upper and lower cables and the spacer plate. A base of the channel may also be shaped to the profile of the lower cable to be received therein.

By so shaping the channel, spacer plates and pressure plates have most effect of electrical contact and connection takes place.

The connector according to the invention is of extremely neat appearance in that the upper and lower cables are arranged one above the other, and this arrangement also results in saving space compared to the W or M connectors described above.

Connectors according to the invention also have the desirable feature that they can be used with a sleeve encapsulation method which involves encapsulation of the connector in a heat shrinkable sleeve which is positioned over the connector and is then heated to cause the sleeve, which is of polymeric material, to shrink around the connector and the cables connected thereby. Such sleeve, as is known in the art, includes internally a heat sensitive adhesive which softens and flows around the connector to seal same when the sleeve is heated and shrunk into position.

When connectors according to the invention are designed for use in this method, it may be desirable to shape the outer profile of the channel member to provide as few sharp corners as possible, as such sharp corners could cause puncturing of the sleeve.

When the connector is used for connecting cables of the same dimension, the inner walls of the channel may be flat, and the pressure plate when provided will be of the same width as the spacer plate, but if say the upper cable is of smaller dimension than the lower cable, then the inner walls of the channel member may be provided with inwardly directed shoulders to define a gap for receiving a smaller sized pressure plate, and for receiving a smaller sized cable.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 is an end elevation of an electrical connector according to the first embodiment of the invention; Figure 2 is a perspective view of the connector shown in Fig. 1; Figures 3 is a view similar to Figs. 1, but show the second embodiment of the invention.

In each of the drawings, the connector is shown as coupling two electrical cables, namely a top cable T and a bottom cable B.

In the case of Fig. 1, the top cable T and the bottom cable B are of similar dimension, whereas in the case of Fig. 3, the top cable T is smaller than the bottom cable B.

Referring to Figs. 1 and 2, the connector comprises a channel member 10 which is rounded to the outside so as to present an approximate heart shape, and the inner walls of the channel space 1 2 are parallel. At the top of each wall is provided a half dove tail groove 14 which receives slidably half dove tail formations 1 6 on a bolt or clamp plate 18. The bolt or clamp plate 1 8 can be slid into and out of engagement with the channel member by moving same in the direction of arrow 20 in Fig. 2.

The clamp plate is provided with two shear head clamp bolts 22, 24, of the configuration shown which have a shear throat 26, which is designed so that the head of the bolt will shear from the threaded stem portion when the bolt has been tightened to a predetermine degree. It is noted at this point that it is important that the achievement of the correct clamping pressure in connectors of the type to which the present invention relates is important for the most effective electrical conduction between the cables and connectors, but it is also to be mentioned that it is not necessary for the present invention that shear head bolts be used.

The inner ends of the bolts 22, 24 engage the top surface of a pressure plate 28, the underside of which is convex as shown at 30.

The plate 28 fits between the channel walls with clearance so as to be easily movable relative thereto.

Between the cables T and B is a specification plate 29 of the same width as the pressure plate, but the top and bottom surfaces of the separation plates 29 are concave as shown at 34 and 36 so that the cables T and B which are of round configuration will contact the separator plate 29 so that there will be maximum electrical contact between the cables and the separator plate 29. It is also possible to achieve this effective electrical contact when cables such as T and B are simply clamped directly together.

In order to make the connection between the cables T and B using the connector according to Figs. 1 and 2, reference is best made to Fig. 2.

Initially, the separator plate 29. the pressure plate 28, and the clamp plate 1 8 with the bolts 22 and 24 are detached from the channel member 1 0. The mains cable B to which electrical connection is to be made, is bared of its insulation as shown by reference numeral 40, and the bared portion is located in the base of the channel 1 0. Next the separator plate 29 is positioned over the bared portion of cable B, and the bared end of the cable T, is positioned over the separator plate 29. Over the bared portion of cable T is positioned the pressure plate, and finally the clamp plate 1 8 is slid into position and the screws 22, 24 are tightened until the heads shear off. The clamp plate 1 8 grips by virtue of the half dove tail joints 1 6 against the top edges of the channel walls, and the cables T and B are clamped to the separator plate 29, the channel member 10 and the pressure plate 28 using the same bolts.

The arrangement shown in Fig. 3 is almost identical to that shown in Figs. 1 and 2, except that the inner walls of the channel are provided with shoulders 50 thereby to create a narrower gap 52 to receive a narrower pressure plate 28.

Claims

1. An electrical connector comprising a channel member and a spacer plate of electrically conductive material, such spacer plate being of a size to fit in the channel with its plane lying transverse to the channel walls, whereby two electrical cables to the electrically connected can be located respectively above and below the spacer plate so as to be in electrical contact therewith, the connector also having clamping means for urging the top cable on to the spacer plate, the spacer plate on to the lower cable and hence the lower cable into contact with the channel member.

2. A connector according to claim 1 wherein the clamping means comprises a bolt or clamping plate in which one or more clamp bolts is or are carried and which is connectable to the channel so as to be restrained from movement relative to the channel in the direction of the channel walls in order to achieve firm clamping of the cables when the bolt or bolts is or are tightened.

3. A connector according to claim 2 wherein the clamping means additionally includes a pressure plate which is for rotation between the end or ends of the clamp bolt or bolts and the top cable.

4. A connector according to claim 3, wherein the pressure plate surface which faces the top cable is of the concave nature and has serrations thereon, for the effective electrical contact with the upper cable, whilst the said spacer plate has its upper and lower surfaces concave and optionally serrated for the effective contact between the upper and lower cables and the spacer plate.

5. A connector according to any preceding claim wherein the base of the channel is shaped to the profile of the lower cable to be received therein.

6. A connector according to any preceding claim, wherein the inner walls of the channel are flat, and the pressure plate when provided is of the same width as the spacer plate.

7. A connector according to any of claims 1 to 5, wherein the inner walls of the channel member are provided with inwardly directed shoulders to define a gap for receiving a pressure plate which is smaller than the spacer plate.

8. An electrical connector substantially as hereinbefore described with reference to Figs.

1 and 2 or Fig. 3 of the accompanying drawings.

9. An installation comprising a connector as claimed in any one of the preceding claims when connecting two electrical cables, and including sleeve encapsulation surrounding the connector.

10. An assembly according to Claim 9, wherein the sleeve encapsulation comprises a heat shrinkable sleeve heat shrunk onto the connector, and including a heat sensitive adhesive inside the sleeve which softens an enclosure connected to seal same.