GB2311662A - Clamp for connecting conductors - Google Patents

Description

CONNECTOR The invention which is the subject of this patent application relates to an electrical conductor connector for use in the joining together of electrical conductors in the form of cables and in the joining together of branch, main and/or service cables and the like and typically, but not exclusively for use underground.

The provision of connectors to join electrical conductor cables is well known and there are many different forms of connectors currently available and the form and size of the same is largely dependent upon the particular conductor cables to be joined together and the shape and formation of the same. Typically, if the connectors are to be used underground, then once the connection has been made, the connector is encased in a resin which is held within a shell to protect and electrically isolate the connector.

The electrical connector type of particular interest is a connector for use in the joining together of low voltage conductors such as branch or service conductors for domestic or business premises which are connected to a main supply conductor cable.

A first known type of connector comprises two parts which are provided with location formations for the reception of conductors therein in a side by side relationship and the said two parts are clamped together by means of tightening a bolt or bolts to bring the two parts together and hence clamp the conductors in the location formations. The connector of this type is particularly useful in relation to the connecting of solid core conductors but problems are encountered for use of the connectors with stranded conductor cores. The problem when used with stranded conductors is that when the parts are clamped together, the strands of the conductors tend to escape from the longitudinal open sides of the connector parts.

A known solution to this problem is to provide overlapping side edges on the parts which, when the parts are joined together overlap to effectively close the open sides of the connector and hence prevent any strands from escaping from the connector sides.

The connectors are typically provided of varying lengths depending upon the size of cables to be joined together and also the particular use of the conductors which are to be joined such that, for example, relatively short versions of the connector are provided for use with low voltage service conductors and longer versions of the connector are used when mains conductor cables are to be connected.

Furthermore, the connectors can be used for what are known as straight joints wherein both conductors lie in a parallel side by side relationship and the ends of the same are joined together by the connector or for branch connections wherein there is provided one conductor running through the connector and connected to the end of a branch or service conductor also located in the connector.

Another known feature of connectors of this type is that they can be used for a relatively wide range of conductor sizes such as, for example, a connector which has a capacity to handle conductors of 300 mm2 in cross section can still be capable of connecting conductors of as little as 35main cross section and below. This causes problems with the conventional type of connector and especially when provided with overlapping edges as the two parts of the connector are joined together with a clamping bolt passing through a hole or slot in one part of the connector and into a threaded bore provided in the other part and the connector which is required to be supplied with a bolt shaft of sufficient length to allow the connector parts to be opened apart to provide a gap between the edges which is wide enough to allow the conductors to be moved into position between the parts and, when fitted, the bolt is turned to clamp the conductors such that the bolt shaft passes through the threaded bore in the second part and protrudes through the same and hence outside the connector.

The connector is provided with the bolt in place connecting the two parts in order to avoid the need for the operator when fitting the connector in situ to attempt to locate the bolt into a threaded aperture as, when one considers that the fitting of the connector may take place in conditions which are wet and/or dirty and with the operator wearing insulating gloves to avoid electrical shock it will readily be appreciated that it would be difficult in a conventional connector form for the bolt to be threaded into an aperture.

Furthermore the aperture can become clogged up with foreign matter.

As these conductors are capable of receiving a number of sizes of conductors therein over a large range if a small conductor is placed in the connector the bolt shaft which is required to be sufficiently long to operate with large conductors protrudes to a significant extent from the connector. This is a significant inconvenience as all of the connector and the protruding shaft is required to be enclosed within the joint shell and resin. This problem is further increased if the connectors are used to join three phase cable conductors which have three cables as, because it is normal to have the bolt heads facing outwardly from the centre of the three cables for ease of access to the operator when tightening the same so the protruding ends of the bolt shafts face towards the centre of the cables and hence the protruding shafts of the three connectors are close to one another. One possible solution is to stagger the connectors along the cable so that the bolt shafts are staggered but this means that the shell length and resin required increases and a larger excavation for underground cables is required. If however the connectors are held in close proximity there is a significant danger that a phase to phase short circuit in the conductors will occur by the protruding shafts touching and this is obviously undesirable.

The aim of the present invention is to provide a connector which allows a relatively wide range of conductor sizes to be secured thereto and yet which does not have a bolt shaft significantly protruding therefrom when relatively small sized conductors are secured therein.

In a first aspect of the invention there is provided a connector for electrical conductors to join the same together, said connector comprising two parts which are movable together into a clamped position by a securing means movement of which brings the two parts towards one another with conductors held therebetween and wherein a shaft is secured to one of said parts and passes through an aperture in the other of said parts to allow the threaded securing means to be attached thereto upon location of the conductors in position between the two parts.

In one preferred embodiment of the invention, the connector parts are provided with formations along the longitudinal edges thereof such that when the parts are brought into a clamping position on the conductors held therein, the formations either interlink or one passes over the other to effectively close the longitudinal edges of the connector and prevent the escape of or access to parts of the conductors therethrough.

In one embodiment, the formations are provided in matching male and female form such that the same interlink when brought together or, in an alternative embodiment, one of the edges at each side is longer than the other such that it overlies the other.

In whichever embodiment, the extent of the formations is such that the longitudinal side edges are effectively closed regardless of which of the conductor sizes is located in the connector within a predetermined range.

In one embodiment the shaft is located on one of the parts of the connector by any of; an extruded groove in the part to locate the hexagonal bolt head therein and deforming the same to secure the hexagonal head in position in the part; or providing the shaft with a first threaded section to allow the same to be threaded into a threaded aperture in the part to secure the shaft in position and a second threaded section towards the other end of the shaft upon which the securing means for the connector is threaded or; thirdly the shaft is threaded along its length and one end of the same is placed into a threaded aperture in the part and when in position, the thread is deformed to prevent subsequent movement of the shaft from the part.

In whichever form, the shaft is secured in the part and the connector can preferably be provided with the shaft already secured to one of the parts or can be provided in a disassembled form.

Typically the first and second parts of the connector are provided with location formations formed along the length thereof, each part having a pair of location means provided in a side by side parallel position thereby allowing the reception of two conductors therein in a side by side parallel relationship.

In one particularly advantageous arrangement, the parts are formed from extruded aluminium but can be plated so that they can be used with either copper or aluminium conductor cores.

Thus, the connector according to this invention provides significant advantages in that if three phase conductors are joined by three of the said connectors the part of the connector which faces the centre has no protrusions and the operator can still tighten the two parts of the connector together by tightening the securing means onto the shaft and, the securing means can be easily accessed by the operator and so the connectors can be placed relatively close together thereby reducing the overall size of the join. Furthermore, with the shaft fixed to one part of the connector, the same can be provided in a disassembled condition to the operator and thus the length of the shaft is not determined by the extent to which the two parts are required to be moved apart to allow the introduction of the conductors but rather is only required to be of a length which matches the size of the conductors to be placed therein, plus the size of the part which is to be placed thereover and a sufficient additional length to allow securing means to be positioned thereon.

This therefore allows a considerable reduction in the length of the shaft which is provided and hence the shaft does not protrude significantly outside the connector body.

In use, the connector is provided disassembled and comprises two parts, a first part having a reception means for a shaft, and a securing means. The first part is therefore placed to one side of the conductors which are to be connected and the conductors are placed in position on the location means on the part. The shaft is typically provided already fitted to the first part under factory conditions but, if required the shaft can be inserted into the first part on site, prior to the placement of the conductors in position. In any case, the second part is placed over the conductors and the shaft passes through an aperture in the second part. With the first and second parts held on the conductors, so the securing means can be threaded onto the shaft and tightened until the parts are sufficiently held together to provide a clamping effect and the required electrical connection of the conductors. Thus the length of shaft which subsequently protrudes from the connector is significantly smaller than with conventional connectors even when the smallest conductors are held in the connector.

In one embodiment, the first and second connector parts are of a constant size for any of a range of conductors but the size of shaft can be provided of a required length for use with particular conductor size ranges. In one embodiment, a universal shaft can be provided with a series of weakening points therealong and each of the weakening points corresponds to a particular length of shaft which is required for a particular size of conductor and thus can be broken off by the operator prior to the use of the same, but preferably after the securing means has been applied to exert the required clamping force. In any embodiment it should be pointed out that the extent of protrusion of this shaft from the connector is significantly smaller than with conventional connectors as the length of the same is only required to be determined by the requirement of the same to be of sufficient length to match the maximum size of conductor to be fitted into the connector and the thickness of the second part of the connector plus an additional length for the securing of securing means thereon whereas, with conventional connectors, the shaft is required to be of a length as above plus an additional amount to allow the parts to be moved apart to a sufficient extent to allow the introduction of the conductor to a position between the parts. This problem is further exacerbated by the provision of overlapping side edges and hence in conventional cases the length of shaft which is required is substantially longer than that according to the present invention as the two parts are connected by the shaft at all times.

In a further aspect of the invention there is provided a method for connecting at least two electrical conductors together said method comprising the steps of providing a connector comprising at least a first part and a second part for placing on opposing sides of the conductors to be connected, a shaft attached in use to one of said parts and, securing means for placement on the shaft, the method comprising the steps of placing a first part to one side of the conductors to be connected, placing the conductors in the location means formed on the first part, said first part including the shaft so that it protrudes in a direction passing the conductors placed in the first part, placing the second part onto the conductors and passing the shaft through an aperture in the second part, introducing the securing means onto the shaft and tightening the same to contact the second part and move the second part towards the first part thereby exerting a clamping force on the conductors.

It should be appreciated that in one embodiment, the shaft may be secured to the first part when supplied for use or, alternatively, assembled on site prior to the introduction of the conductors onto the first part. In any case, the first and second parts can be separated to allow the conductors to be placed therein.

In whichever of the embodiments of the apparatus and/or method, it should be appreciated that more than one shaft can be provided and that, if necessary, a plurality of shafts can be located along the length of the first part.

Specific embodiments of the invention will now be described with reference to the accompanying drawings wherein: Figures 1A and 1B illustrate a conventional connector in end elevation in a formation prior to connection and after connection; Figure 2 illustrates a series of conventional connectors as shown in Figure 1 used to connect the three cables of three phase conductors; Figure 3 illustrate the first part of a connector according to the invention; Figure 4 illustrates the first and second parts of the connector in position according to the invention; Figures 5A and 5B illustrate two arrangements of formed connector according to the invention in use; Figure 6 illustrates three connectors according to the invention in use to join the cables of three phase conductors; Figures 7A to 7C illustrate three alternative arrangements for locating the shaft into the first part of the connector according to the invention; Figure 8 illustrates one form of a first part according to the invention; and Figure 9 illustrates a form of a second part according to the invention.

Referring firstly to Figures 1A, 1B and 2, there is shown a conventional connector. Referring firstly to Figure 1A there is shown a connector comprising a first part 2 and a second part 4 which are mounted on a bolt 6. The bolt 6 has a shaft 8 which passes into a threaded aperture in one of the parts 2 and the second part 4 is movable between a position in which it is removed from the first part 2 and adjacent the bolt head and a second position as shown in Figure 1B wherein the part 4 is provided in contact with the first part 2 to clamp conductors 14 therein and hence connect the same. In the open position as shown in Figure 1A, sufficient space is provided to allow the conductors 14 to be introduced into location slots 16. With the conductors in position, the bolt is turned and moved relative to the first part such that the bolt head and hence second part 4 are brought into engagement with the first part to clamp and connect the conductors 14 as shown in Figure 1B.

However, because the movement of the bolt 6 is relative to the first part, so the shaft 8 of the same when in a securing position as shown in Figure 1B protrudes to a significant extent from the first part 2 and this protrusion causes substantial disadvantages in the provision of the connector of this type as it becomes bulky and, as connections of this type are normally held in a joint shell which is filled with resin, so the shell is required to be of a larger size to include the length of the bolt shaft which protrudes from the connector.

This problem is further exacerbated when three of the connectors are used to connect the conductors of three phase conductor cables as shown in Figure 2 wherein with each of the conductors in a connecting position with parts 2 and 4 with conductors 14 therebetween, the shaft protrusions 8 of the bolt face inwardly in each connector. The bolt 6 head is required to be positioned to face outwardly of the connectors such that the same can be accessed to allow the same to be turned to move the parts 2 and 4 together by the operator who is forming the connections. The protrusions 8 of the bolt 6 can touch due to their proximity and, if they do touch, phase to phase short circuit can occur.

The shaft 8 of the bolt 6 is required to be of sufficient length to allow the first and second parts 2 and 4 to be moved apart as the same are held within the length of the shaft 8 at all times as shown in Figure 1A to allow the introduction of the conductors into the connector. This requirement is further increased by the fact that the first and second parts are provided with overlapping jaws 16 provided to prevent escape of conductor strands from the sides of the connector when in a clamped position.

Referring now to Figure 3 there is shown a first part 20 of a connector according to the invention and the said first part includes secured thereto a shaft 22 which is threaded at both ends thereof. At the first end 24 the thread is of a length to allow the same to be screwed into a threaded aperture 26 in the first part 20 and hence the shaft is secured thereto. The first part can be provided for use with the shaft shown in this position or, alternatively, the shaft can be placed into position by the operator to assemble the same prior to use on site. The first part is provided with overlapping edge jaws 28 and location means 30 for location therein of the conductors 32 as shown.

Figure 4 illustrates the connector according to the invention with the first part 20 shaft 22 and conductors 32 in connection with the second part 34 of the connector according to the invention. The second part 34 is provided with an aperture 36 which allows the shaft 22 to pass therethrough and hence the end 38 is provided for the reception of securing means 40 is, in this embodiment, a nut 40 as illustrated in Figure 5A and 5B and the nut is introduced onto the shaft 22 when the second part 34 is in position on the first part 20.

The securing means 40 is then tightened and moved down the shaft 22 to force the second part 34 into contact with the first part 20 and hence clamp and connect the conductors 32 held therebetween. In one embodiment the securing means can include a torque control mechanism to ensure that the correct clamping torque is applied.

Thus it is only necessary for a relatively small portion of the shaft 22 to protrude from the body of the connector 20, 34. In Figure 5A the connector is used to connect relatively large conductors which are at the upper limit of the conductor range and it can be seen that the shaft 22 only protrudes from the connector to the extent of the width of the nut 40 and in Figure 5B there is shown the connector in use to connect conductors of a size towards the lower limit of the range and even in this embodiment, the shaft 22 only protrudes for a relatively short length from the connector body. Furthermore it should be noted that in both Figures 5A and 5B the side edges of the parts 20, 34 are shaped such that they still overlap to prevent the escape of any strands of the conductors held therein.

Referring now to 7A to 7C there are shown three possible arrangements for securing the shaft 22 to the first part 20 of the connector according to the invention. In Figure 7A the shaft 22 is provided with a hexagonal head 42 which is placed into an aperture 44 in the first part 20 and the aperture is then at least partially closed behind the head 42 to retain the said head in the position in the first part and prevent the same from being subsequently removed.

Figure 7B illustrates an alternative arrangement wherein the shaft is provided with two threaded sections. A first threaded section 46 which is provided to allow the shaft to be screwed into a threaded aperture 48 in the first part 20 and hence secure the shaft into position therein. The other threaded section 50 is provided for the reception of the securing means 40 thereon as illustrated in Figure 5A and 5B.

Figure 7C illustrates a yet further embodiment wherein the shaft 22 is threaded along its length and one end 52 of the same is screwed into the threaded aperture 48 in the first part 20 and, when the shaft is threaded to an extent that the shaft is in the required position, the thread is deformed to prevent the subsequent removal of the shaft.

Figures 8 and 9 illustrate the first and second parts of the connector in greater detail and in particular, Figure 9 illustrates the manner in which two shafts 22 can be provided in the connector part if, for example, the connector to be provided is relatively long. Both the first and second parts 20, 34 are provided with side edge formations 54 which, when the two parts are brought together interlink to form at least partially closed longitudinal side edges of the connector and thereby prevent the escape of any strands of the conductors held within the same.

Figure 6 illustrates three of the connectors according to the invention in an embodiment used to connect the conductors of three phase cables and it can quite clearly be seen that by using the connector of a form according to the invention, so the connectors can be located significantly closer together than shown in Figure 2 using conventional connectors. This is because the shafts 22 do not protrude from the underside of the connector and hence there is no danger of any protrusions contacting and causing short circuiting.

Thus as, the second part is movable only in relation to the first part of the connector and there is no relative movement of the shaft 22 relative to the first part of the connector so the protrusion of the shaft is eliminated and thus, the problems of the conventional connectors are overcome by securing the shaft 22 to the first part 20 of the connector and moving the second part and the securing means relative thereto.

To use a connector according to the invention, the first part 20 with the shaft 22 secured thereto is placed on the side of the conductors opposing that of the operator fitting the connector. The conductors are then placed into the location means 30 of the first part and, with the conductors in position, the second part is placed with the shaft 22 passing through the aperture 36 therein and moved down onto the conductors 32. Securing means 40 are then placed onto the shaft or shafts 22 provided and tightened to contact the second part 34 and effectively clamp the second part in a tightened position onto the first part 20 hence clamping the conductors in a required position.

It is therefore submitted that the connector according to this invention with the features described herein has considerable advantage over conventional connectors both in terms of use and safety, in that the overall dimension of the formed connector are reduced yet allows the conductor size range which can be accommodated in the connector to be maintained. Furthermore the connector according to the invention allows the same to be fitted on site even by an operator wearing insulating gloves, easily and with a minimum of parts required to be located on each other.

Claims (11)

1. A connector for electrical conductors to join the same together, said connector comprising at least two parts which are movable together into a clamped position by a securing means, to secure conductors held between said parts and wherein the securing means includes a shaft secured to one of said parts which passes through an aperture in the other of said parts to allow a locking means to be attached thereto upon location of the conductors in position between the two parts.

2. A connector according to Claim 1 wherein the parts are provided with formations along the longitudinal edges thereof such that when the parts are brought into a clamping position on the conductors held therein, the formations effectively close the longitudinal edges of the connector.

3. A connector according to Claim 2 wherein the formations along the edges of the parts are provided in matching male and female form such that the same interlink when brought together.

4. A connector according to Claim 2 wherein one of the edges at each side of the connector protrudes in relation to the other such that it overlies the other.

5. A connector according to Claim 1 wherein the shaft is provided with a bolt head and one of said parts is provided with an extruded groove to locate the bolt head therein and hence the shaft to the part.

6. A connector according to Claim 1 wherein the shaft is provided with a first threaded section to allow the same to be threaded into a threaded aperture in one of the parts to secure the shaft in position.

7. A connector according to Claim 1 wherein the shaft is threaded along its length and one end of the same is placed into a threaded aperture in one of the parts and formed to prevent subsequent movement of the shaft from the part.

8. A connector according to Claim 1 wherein the first and second parts are provided with location formations formed along the length thereof for the reception of conductors therein.

9. A conductor according to Claim 8 wherein each of the parts has a pair of location means provided in a side by side parallel relationship thereby allowing the reception of two conductors therein in side by side relationship.

10. A method of forming a connection according to the present invention comprising the steps of providing a first and second part of the connector, securing a shaft into one of said parts, placing said part to one side of the conductors which are to be connected, placing the conductors in position in location means on the said part, placing the second part over the conductors and passing said shaft through an aperture in the second part, introducing locking means to the shaft to secure said first and second parts to exert a clamping force on said conductors and provide electrical connection thereof.

11. A method according to the preceding claim wherein a plurality of shafts are provided along the length of the conductor parts and locking means is provided for each of the shafts.