GB2383200A

GB2383200A - Cable positioning system having a belt

Info

Publication number: GB2383200A
Application number: GB0129706A
Authority: GB
Inventors: Simon Neve
Original assignee: Balfour Beatty PLC
Current assignee: Balfour Beatty PLC
Priority date: 2001-12-12
Filing date: 2001-12-12
Publication date: 2003-06-18
Anticipated expiration: 2021-12-12
Also published as: GB2383200B; GB0129706D0

Abstract

A cable positioning system is for moving an unrolled cable from a first position to a lower second position. The cable is supported along its length by guide devices which have first and second rollers 30,32 with a belt 34 extending around the rollers, arranged such that the belt extends between the upper and lower cable positions. A support 36 is on the belt for supporting the cable. A belt is thus used to transport a portion of the cable from a higher first position to a lower second position where it can be retained in mounting clips 25. The belt can move under the weight of the cable, and is controlled by a brake in the form of a clutch controllable with a handle 38. The system is hooked on a support beam 20, and is adjustable for different clip positions (fig 3B). This provides a fully mechanical arrangement, but which eliminates the need for any heavy lifting by the installation team. The system has advantages when used in tunnels.

Description

CABLE INSTALLATION This invention relates to cable installation, in particular to the positioning of cable, for example in tunnels or other ducts.

The positioning of cable into tunnels or other ducts presents particular difficulty, as the drums on which cable is supplied will typically not fit into the tunnel, so that the cable has to be fed into the tunnel lengthways.

It is known unroll the cable from the drum into the tunnel and to provide support for the cable on a pulley-type arrangement, which then enables the cable to rolled along the tunnel to the desired position. When the unrolled cable has been moved to its final position within the tunnel, the cable is then released from the pulleytype arrangement and is positioned within retaining clips spaced along the length of the cable, normally on the inside side wall of the tunnel. This has conventionally been carried out by an installation team. As a result of the weight of the cable, the cable is progressively removed from the pulley-type arrangement and attached to the retaining clips, so that the full weight of the cable is never operated on manually.

For some cable types, even manually moving a portion of the cable may be difficult. For example, a 400kV cable may typically weigh around 40kg/m. The spacing between retaining clips will be 5 to 10 metres, so that even the portion of the cable between retaining clips may weigh around 300kg.

There is therefore a need for a system for moving an extended cable from a first position (when it is supported by the pulley-type arrangement) to its final position, and which avoids the need for an installer to have to manipulate heavy sections of cable.

According to the invention, there is provided a cable positioning system for moving an unrolled cable from a first position to a second position, wherein the second position is lower than the first position, comprising: a support rail; a plurality of retaining members disposed along the length of the cable for retaining the cable in the first position supported by the support rail;

a plurality of guide devices, each guide device being provided for moving a portion of the cable from the first position to the second position, each guide device being releasably supportable on the support rail, wherein each guide device comprises: first and second rollers with a belt extending around the rollers, arranged such that the belt extends between the first cable position and the second cable position; a support member on the belt for supporting the cable; and a braking arrangement for the belt.

This arrangement provides a belt which can transport a portion of the cable from the higher first position to the lower second position where it can be retained in mounting clips. The belt can move under the weight of the cable, and is controlled by a brake. This provides a fully mechanical arrangement, but which eliminates the need for any heavy lifting by the installation team.

A plurality of retaining clips are provided for retaining the cable in the second position, and the cable is moved into its final position one clip at a time. Preferably, the guide device has an end portion arranged to engage with a retaining clip. In this way, the belt is supported at one end by the support rail and is supported at the other end by the retaining clip.

There may be a plurality of second positions, and a plurality of retaining clips are provided for each second position. Each second position may, for example, be for a different phase of a three phase supply.

The braking arrangement may comprise a clutch which allows the control of movement of the belt around the rollers.

The cable positioning system preferably forms part of a cable supply and positioning system which has a feed mechanism for feeding a rolled cable from a drum into the first position. The feed mechanism can be locating outside a tunnel and the positioning system can be inside the tunnel.

The invention also provides a method of positioning a cable, comprising: (i) supplying a cable to a first position, in which the cable is suspended from a support rail; (ii) moving a portion of the cable from the first position to a second position using a guide device which is releasably supported on the support rail, the guide device comprising first and second rollers with a belt extending around the rollers, arranged such that the belt extends between the first cable position and the second cable position;

(iii) removing the guide device from the support rail; and (iv) placing the (or another) guide device at a different portion of the cable if required; and (v) repeating steps (ii) to (iv) until the cable has been fully moved from the first to the second position.

In this method, portions of the cable are moved in turn from the first position (which is the position in which the cable is supplied to the tunnel) and the second position (which is the final position in the tunnel), using a mechanical device. Once a portion has been moved, the guide device can be unhooked from the support rail, and moved to the next position along the cable.

A plurality of retaining clips can be provided for retaining the cable in the second position, and the step of moving a portion of the cable may further comprise retaining the moved portion of the cable using a retaining clip. Placing a guide device may comprise suspending the guide device from the support rail and engaging an end portion of the guide device with a retaining clip.

Before starting to move portions of the cable, a plurality of guide devices (for example 2 to 10) can be placed at one end of the cable. The plurality of guide devices can each hold their cable portion at a different position so that sharp bends in the cable are not needed.

In order to move a portion of the cable, a clutch can be released to allow the belt to move around the rollers driven by the weight of the cable acting on the belt.

This method can be used for installing a cable in a tunnel.

An example of the invention will now be described in detail with reference to the accompanying drawings, in which: Figure I shows a known system for installing cable into a tunnel; Figure 2 shows a positioning system in accordance with the invention, for use in combination with the system of Figure 1; and Figure 3 shows how the positioning system of the invention can position a cable in a choice of positions.

Figure 1 shows a known system for installing a cable into a tunnel. The cable 10 is supplied on a drum 12, having a motorised drumstand 14. Motorised rollers 16

are used to feed the cable 10 into a guide tube 16, which leads the cable to the top of the tunnel 18. The cable is thus unrolled and fed to the tunnel. Inside the tunnel 18, the cable is supported from a support beam 20 by beam rollers 22 which support a cable hanger 23. The support beam will have functions other than supporting the inserted cable, for example the beam may be used subsequently to support an inspection vehicle The beam rollers 22 can roll along the support beam 20, carrying the cable with them. As the cable is advanced, beam rollers 22 are provided for example every 5m, at the tunnel opening. The cable is fully unrolled in and supported along its entire length by the support beam 20.

The cable is then moved from the support beam 20 to a series 24 of clips, which are spaced every 5 to 1 Om. This is carried out by an installation team.

The invention provides a system for moving the cable from the support beam (a

first position) to the retaining clips (a second position), for improving the arrangement p of Figure 1, and this positioning system is shown in Figure 2.

The system has first and second rollers 30,32 with a belt 34 extending around the rollers. The belt extends the cable suspended from the support beam 20 and a selected retaining clip 25. A support member 36 is provided on the belt for supporting the cable and preventing the cable slipping down the belt.

The cable can be moved from the first position to the second position under its own weight, which acts on the support member 36 to drive the belt 34 around the pulleys. A braking arrangement is provided for controlling the movement of the belt, in the form of a clutch in one or both of the rollers 30,32. The (or each) clutch is controllable with a handle 38, which allows or prevents the rollers 30, 32 from rotating about their axis. When rotation is prevented, the belt remains stationary as a result of the frictional (or toothed) engagement of the inside of the belt 34 with the rollers 30, 32.

This provides a purely mechanical arrangement for moving the cable, under its own weight, and which can be controlled easily and safely.

The device is hooked onto the support beam 20 with a hook arrangement 40, and also a free end of the belt, at the second roller 32, is hooked onto the selected clip 25 using a hook 42 which engages with a projection 44.

As shown in Figure 2, the series 24 of clips 25 may have a number of clips, in particular three clips, one for each phase. There are thus three"second positions", and

the same guide device can be used for moving the cable from the first position to any of the three second positions.

Figure 3 shows in greater detail how a single design can be used for multiple positions. Figure 3A shows the device of the invention being used to move a cable to the middle 25a of three clips. The first roller is connected to the hook 40 by an arm 50.

By supporting the device from the beam 20 and on the projection 44, the length of the arm 50 is such that the belt extends between the first position and the selected clip 25a.

The same occurs for any of the three clip position, for example the lower clip 25b as shown in Figure 3B.

In order to install a cable using the system of the invention, the cable is supplied to the first position in conventional manner. The cable may weigh 41kg/m, and a typical application may be a tunnel of length 20km. The cable is supplied on drums carrying 1 km of cable, for example with diameter 150mm.

Once a 1km length is positioned at the desired position, it is moved to the clips on the side wall. The lengths of cable are joined after they have been moved to the clips, so it makes no difference if all 1km sections are first provided along the support beam or if they are moved to the side wall as soon as they have been provided to the tunnel.

A number of the guide devices, for example 6, are provided at one end of the cable, for example every 8. 4m. The cable is released from the support beam 20 over this section of the cable, and the six belts are moved in unison, so that there is a gradual curve in the cable profile. The belts are moved by controlling the clutches. When the guide device at the end of the cable has moved that cable portion all the way to the retaining clip, the guide device is unhooked and moved to the back of the line of guide devices. In this way, the cable is progressively moved to the tunnel side wall, and the train of six guide devices moves along the cable.

Of course, a different number of guide devices may be in the train, for example only three.

Variations will be apparent to those skilled in the art.

Claims

1. A cable positioning system for moving an unrolled cable from a first position to a second position, wherein the second position is lower than the first position, comprising : a support rail; a plurality of retaining members disposed along the length of the cable for retaining the cable in the first position supported by the support rail; a plurality of guide devices, each guide device being provided for moving a portion of the cable from the first position to the second position, each guide device being releasably supportable on the support rail, wherein each guide device comprises : first and second rollers with a belt extending around the rollers, arranged such that the belt extends between the first cable position and the second cable position; a support member on the belt for supporting the cable; and a braking arrangement for the belt.

2. A system as claimed in claim 1, further comprising a plurality of retaining clips for retaining the cable in the second position.

3. A system as claimed in claim 2, wherein the guide device has an end portion arranged to engage with a retaining clip.

4. A system as claimed in claim 2 or 3, wherein there are a plurality of second positions, and a plurality of retaining clips are provided for each second position.

5. A system as claimed in any preceding claim, wherein the braking arrangement comprises a clutch which allows the control of movement of the belt around the rollers.

6. A cable supply and positioning system comprising a system as claimed in any preceding claim and a feed mechanism for feeding a rolled cable from a drum into the first position.

7. A system as claimed in claim 6 for positioning a cable against a side wall of a tunnel, wherein the feed mechanism for locating outside the tunnel and the positioning system is for locating inside the tunnel.

8. A method of positioning a cable, comprising: (i) supplying a cable to a first position, in which the cable is suspended from a support rail; (ii) moving a portion of the cable from the first position to a second position using a guide device which is releasably supported on the support rail, the guide device comprising first and second rollers with a belt extending around the rollers, arranged such that the belt extends between the first cable position and the second cable position; (iii) removing the guide device from the support rail; and (iv) placing the (or another) guide device at a different portion of the cable if required; and (v) repeating steps (ii) to (iv) until the cable has been fully moved from the first to the second position.

9. A method as claimed in claim 8, wherein a plurality of retaining clips are provided for retaining the cable in the second position, and wherein the step of moving a portion of the cable further comprises retaining the moved portion of the cable using a retaining clip.

10. A method as claimed in claim 9, wherein the step of placing the (or another) guide device comprises suspending the guide device from the support rail and engaging an end portion of the guide device with a retaining clip.

11. A method as claimed in claim 8,9 or 10, wherein the step of moving a portion of the cable comprises moving a portion of the cable to a selected one of a plurality of second positions.

12. A method as claimed in any one of claims 8 to 11, further comprising placing a plurality of guide devices at one end of the cable after supplying the cable to the first position and before moving the first portion of the cable.

13. A method as claimed in claim 12, wherein the plurality of guide devices comprises 2 to 6 guide devices.

14. A method as claimed in any one of claims 8 to 13, wherein moving a portion of the cable comprises releasing a clutch to allow the belt to move around the rollers driven by the weight of the cable acting on the belt.

15. A method as claimed in any one of claims 8 to 14, wherein a plurality of cables are positioned in the second position end to end, and wherein the cables are electrically and mechanically joined together after positioning.

16. A method as claimed in any one of claims 8 to 15 for installing a cable in a tunnel.