GB2526557A

GB2526557A - Power cables

Info

Publication number: GB2526557A
Application number: GB1409359.5A
Authority: GB
Inventors: David Robert Tanner
Original assignee: L C SWITCHGEAR Ltd
Current assignee: L C SWITCHGEAR Ltd
Priority date: 2014-05-27
Filing date: 2014-05-27
Publication date: 2015-12-02
Anticipated expiration: 2034-05-27
Also published as: GB2526557B; GB201409359D0

Abstract

A power cable, such as a jumper lead 3c provides an alternative power supply from an electrical conductor rail 7 to a gapped electrically-powered train carriage, enabling the carriage to traverse the gap until collector shoes of the carriage are brought back into electrically contact with the conductor rail 7. The power cable comprises: a first connector at one end of the cable that electrically connects with a corresponding connector on the carriage; and a second connector, or jumper shoe 6c, having a contact portion 12 at the other end of the cable to be electrically connected, and removably secured, to the conductor rail 7. The second electrical connector 6c further includes a housing and a terminal portion to connect to the power cable 3c. The contact portion 12 may be secured to the conductor rail 7 via magnets 19 embedded or integrated into the contact portion 12 or by a mechanical means (e.g. clamp, chuck, vice, etc.). By enabling the jumper shoe 6c to be removably secured to the conductor rail 7, an operator does not have to support the cable 3c and may retreat to a safe distance whilst the rail 7 is energised.

Description

Power Cables

Field of the Invention

190011 The present invention relates to power cables, and particularly, although not exclusively, to portable power cables for carrying high currents awl/or voltages for use in the recovery of electric powered carriages.

Background of the Invention

100021 Electric powered carriages that rely on external power sources, for example, trains, trams, monorails, subways, electric buses and carts etc. typically use overhead powered lines and/or powered ground rail systems.

100031 Powered ground rails typically comprises three or four substantially parallel rails typically made from a ferrous material, whereby two of the rails provide support for the wheels of the carriages and the third and/or fourth electrical conductor rails may be used to carry electric current to provide power to the carriages. lii the three rail system the return current. path is through the wheels of the carriage to one or more of the supporting rails. In three or four rail systems, the circuit between the electrical conductor rail or rails and the carriage may be provided by at least one collector shoe on one or more bogies that slides along the electrical conductor rail or rails, such that current is supplied to the electrical equipment on board the carriage.

100041 At junctions, points and/or intersections, gaps arc needed in the electrical conductor rails to allow the carriage to move from one section of the track to the other. In such case, there will he an electrical break in the circuit. Normally, the momentum of the carriage carries it across the gap. However, it is possible that the carriage may become stranded at the junction. point and/or intersection, in particularly in junctions and/or intersections such as at the entrances to rail yards where gaps tend to be large and numerous.

Under such circumstances, the stranded carriage is said to be "gapped".

100051 Although the following description discloses a four rail system, the principal is the same for a three rail system except that only one electncal conductor rail and jumper lead is involved. Gapped carriages are recovered using a pair of jumper leads, whereby each jumper lead comprises a first connector at one end to he electrically connected to a corresponding connector located in a receptacle box on a tractor unit of the carriage, and a second connector in a form of a jumper shoe at the other end to be electrically connected to nearby electrical conductor rails of the correct polarity which have been isolated. With both jumper leads connected in place, the electrical conductor rails are re-energised to provide an alternative power supply to the gapped carriage.

100061 Contact between the jumper shoe and the electrical conductor rail is maintained by the weight of the jumper shoe. The carriage can then be driven the across the gap until the collector shoes make electrical contact with the electrical conductor rail.

100071 The receptade box may also he used for connecting power to the carriage in a maintenance depot, where the presence of high voltage live conductor rails would be a hazard to personnel.

100081 The jumper leads are designed to carry high currents and voltages and therefore have a large cross section and are weB insulated. This makes the jumper leads very heavy and inflexible, and so they have to he supported to ensure good contact between the juniper shoe and the electrical conductor rail. This involves an operator holding the leads to steady the jumper shoes, which puts the operator in close proximity to the live electrical conductor rail.

This exposes the operator to considerable danger. not only from accidental contact with the live dectrical conductor rail, hut also danger due to arcing if the contact between the jumper shoe and the electrical conductor rail is not well maintained.

Statements of the Invention

100091 According to a first aspect of the present invention, there is provided a power cable comprising a first connector at one end for electrical connection to a corresponding connector on an dectrically powered carriage, and a second connector having a contact portion at the other end, the contact portion being arranged to be electrically connected and removably secured to an electrical conductor rail. This may be accomplished by providing each jumper shoe with means to enable the jumper shoe to be removably secured to the electrical conductor rails, such that the operator may retreat to a safe distance before the electrical conductor rails are re-energised. Once the carriage has been driven across the gap, the electrical conductor rails may he isolated to allow the juniper shoes to he safely removed from the electrical conductor rails and the jumper lead to be disconnected from the carriage's receptacle box. This procedure reduces the risk of the operator being exposed to the dangers of high culTent, high voltage and/or in close proximity to arcing.

100101 The contact portion may be removably secured to the rail by magnetic and/or mechanical means.

100111 According to a second aspect of the present invention, there is provided a set of jumper leads comprising at least two said power cables.

100121 According to a third aspect of the present invention, there is provided an electrical connector comprising a housing having a contact portion arranged to be electncally connected and removably secured to a rail and a terminal portion to be connected to a power cable.

100131 There now follows, by way of example only, a detailed description of preferred embodiments of the present invention, with reference to the Figures identified below.

Figures 1 to 3 Ulustrate a typical procedure for recovering a connected series of gapped carriages stranded on a track.

Figure 4 is an exploded isometric view of a jumper shoe from above according to a first embodiment of the present invention.

Figure 5 is an exploded isometric view of the jumper shoe of Figure 4 from below.

Figure 6 is an isometric view of the jumper shoe of Figure 4 when assembled.

Figure? is an isometric view of the jumper shoe of Figure 5 when assembled.

FigureS is a plan view of the jumper shoe of Figures 4 to 7.

Figure 9 is a bottom view of the jumper shoe of Figures 4 to 7.

Figure 10 is an isometric view of the jumper shoe of Figures 4 to 7 mounted on an electrical conductor rail.

Figure 11 is a front view of the jumper shoe mounted on the electrical conductor rail of Figure 10.

Detailed Description of the Embodiments

100141 In the following description, functionally simflar parts carry the same reference numerals between different embodiments. The drawings are intended to be schematic, and dimensions, scale and/or an&es may not he determined accurately from them unless otherwise stated.

100151 In the following description the power cable may be described by the terms power lead, power cord and power wire. It is intended that each term has a similar or equivalent meaning.

100161 In the following description the rail may be described by the terms track or guide.

It is intended that each term has a similar or equivalent meaning.

100171 Within the statement of invention, description and claims, unless otherwise stated, the terms part and portion are intended to have equivalent meaning.

100181 Within the statement of invention, description and claims, unless otherwise stated, when describing electrical connections the terms discrete contact, contact portion and contact area are intended to have equivalent meaning.

100191 Within the statement of invention, description and claims, unless otherwise stated, magnets include permanent magnets. non-permanent magnets and/or electro-magnetic means.

100201 Within the statement of invention, description and claims, unless otherwise stated, (he term removably secured means that a component, assembly and/or device may he securely attached to another component. assembly and/or device, hut readily detachable therefrom.

100211 Figures 1 to 3 illustrate a typical procedure of recovering a connected series of gapped carriages 1 stranded on a first. track 2a using two jumper leads 3a, 3b with prior art jumper shoes ôa, ôh. This procedure may be performed in the following steps: a. Ensure that power supplied to a second track 2b is switched off and isolated; b. Check that the carriages I are secured; c. Connect one end 4a. 4h of each juniper lead 3a, 3h to a corresponding connector, which may be located in a tractor unit la of the carriage's receptacle box 5.

d. Position the jumper shoe 6a, 6b of each jumper lead 3a. 3b on top of each electrical conductor rail 7a, 7h ol the second track 2h and holding the jumper lead 3a, 3h by the insulation portion above each jumper shoe 6a, Oh to steady them. Contact between the jumper shoes 6a, 6h and the electrical conductor rail 7a, 7h is maintained by the weight of the jumper shoe 6a, 6b; e. Re-energise the second track 2b when the carriage 1 is ready to move.

f. Once the carriage I is driven across the gap, power supplied to the second track 21) is switched off and isolated to allow the jumper shoes 6a, 6a to be removed from the electrical conductor rail 7a, 7b of the second track 2b and the jumper leads 3a, 3d to he disconnected from the tractor unit I a.

100221 As described above, this procedure exposes the operator to the dangers of high current, high voltage and/or places the operator in close proximity to arcing.

100231 The present invention aims to alleviate, reduce and eliminate the hazards involved in recovering gapped carriages. The following description discloses improvements to means of removably securing jumper shoes 6c to the electrical conductor rail 7.

100241 Figures 4 and 5 illustrate exploded isometric views of the jumper shoe 6c from above and below according to a first embodiment of the present invention.

100251 As shown, the jumper shoe 6c may comprise a housing 8 having at least two substantially parallel walls 9, wherein each wall 9 may further comprise a substantially horizontal member 10 extending therefrom to form a platform 11 for mounting a contact portion 12 thereto.

100261 The contact portion 12 may be provided with a plurality of apertures 14a which align with apertures I 4h provided on the platform 11, such that the contact portion 1 2 may he secured thereto with a plurality of screw fittings, nuts or the like ISa.

100271 A jumper lead 3c may be electrically and/or mechanically connected to one end of a receptacle 17. The other end of the receptacle 17 may comprise a planished portion 18 having an aperture 16 for receiving a screw, nut or the like 15b. such that the receptacle 17 may he dectrieafly and/or mechanically connected to the contact portion 12. The other end of the jumper lead 3c may be connected to a connector (not shown) for mutually engaging with a corresponding connector provided on the tractor unit I a of the carriage 1.

100281 The contact portion 12 may he made from high electrically conductive material, such as copper or a copper alloy, so that electricity from the electrical conductor rail 7 may be easily transferred to the jumper lead 3c in order to supply electricity to the tractor unit la of the carriage 1. Advantageously, the contact portion 12 may he plated to provide good corrosion resistance. Prelerahly. the contact portion 12 may he made from a non-magnetic material.

100291 As illustrated in Figure 5, the underside of the contact portion 12 may be provided with at least one magnet 19 such that the contact portion 12 may be removably secured to an electrical conductor rail 7, which wifi he described in more detail below.

100301 Advantageously, the contact portion 12 may be provided with a plurality of discrete magnets 19, which may provide a high degree of redundancy if one of the magnets 19, for example, becomes de-magnetised or detached from the contact portion 12.

100311 The magnets 19 may he embedded, housed, reside and/or integrated into the contact portion 12. Advantageously, the magnets 19 may be seated flush and/or recessed into the contact portion 12 to ensure that the contact portion 12 abuts the electrical conductor rail 7. Preferably. each discrete magnet 19 may further be electrically insulated, for example.

coated or treated with an electrically insulated material or coating, so that the discrete magnets 19 may not form part of the current path.

100321 Furthermore, the orientation/positioning and/or the quantity of the magnets 19 may be arranged to suit different profiled rails, rail types and/or to adjust the magnetic attraction force.

100331 At least one brace or member 13 may he provided to ensure that the walls 9 are kcpt substantially parallel and/or improve the rigidity of the housing 8, which will be described in more detail below.

100341 Figures 6 and 7 illustrate isometric views of the jumper shoe 6c from above and below when assembled according to the first embodiment of the present invention. Figures 8 and 9 illustrate a plan view and a bottom view of the jumper shoe 6c according to the first embodiment of the present invention.

100351 When assembled, at least the brace or member 13 and the contact portion 12 ensure that. the two walls 9 are spaced apart and substantially parallel, such that the parallel walls 9 define a channel 20 therehetween for receiving the electrical conductor rail 7. which will he described in more detail below.

100361 Figures 10 and II illustrate isometric and front views of the jumper shoe 6c removably secured onto the electrical conductor rail 7.

100371 Width A of the channel 20 may be controlled by the dimension of the brace 13 and/or the contact portion 12. and is greater than Width B of the electrical conductor rail 7, such that sufficient clearance may he provided to ensure that the electrical conductor rafi 7 resides within the channel 20 without allowing excess movement between the jumper shoe 6c and the electrical conductor rail 7. It can he envisaged that the Width A of the channel 20 may be adjustable and/or adapted to accommodate different widths of the electrical conductor rail 7.

100381 As illustrated in use, the contact portwiri 12 of the jumper shoe 6c abuts the electrical conductor rail 7, so that electricity from the electrical conductor rail 7 may be easily transferred to the jumper lead 3c in order to supply electricity to the tractor unit la of the carriage 1. The jumper shoe ôc may he removably secured to the electrical conductor rail 7 by the magnets 19 without requiring the operator to steady the jumper shoe 6c on the electrical conductor rail 7. This may allow the operator to connect the jumper lead 3c to the ti-actor unit la of the carriage 1 and retreat to a safe distance before the second track is re-energised.

100391 When the carriage 1 has been driven across the gap. the electrical conductor rail 7 of the second track can he isolated, and the jumper shoe ôc and the jumper lead 3c can he safely disconnected. This procedure never exposes the operator to the dangers of high voltage or proximity to arcing. The use of magnets 19 allows the jumper shoe 6c to be easily removed from the electrical conductor rail 7 by rotating, turning, pivoting and/or tilting the jumper shoe 6c with respect to the electrical conductor rail 7.

100401 As illustrated, the jumper lead 3c enters the jumper shoe 6c horii.ontally or in a direction substantially parallel to the electrical conductor rail 7 as opposed to the vertical arrangement shown in the prior art jumper shoes 6a. Oh in Figures 2 and 3. As previously descrihed in the prior art arrangement, the operator would hold the insilated portion of the jumper lead 3a, 3b above each jumper shoe 6a. 6b in order to steady the jumper shoes 6a, 6b.

Since the operator is no longer req uired to hold the jumper leads 3c. the jumper leads 3c can enter the jumper shoe 6c horizontally. This reduces the turning moment of the jumper leads 3c when unsupported by the operator in turn reducing the clamping force required to ensure good contact between the jumper shoe 6c and the electrical conductor rail 7. lii a second embodiment of the present invcntion (not shown), an ins&ated handle may he provided andlor attached to each jumper shoe ôc, to afiow the operator to easily position the jumper shoe 6c on the electrical conductor rail 7. Advantageously, this arrangement also eliminates the operator using the jumper lead 3c as means to steady the jumper shoe 6c, thus eliminating fatigue and/or reducing stresses in joints where the jumper lead 3c is connected to the contact portion 1 2.

F00411 Advantageously, the insulated handle may he provided to rotate, turn, pivot and/or tilt the jumper shoe 6c in order to aid the removal of the jumper shoe 6c from the electrical conductor rail 7. Furthermore, the insulated handled (not shown) may be positioned and/or secured to (he side of the jumper shoe be to allow the jumper shoe 6c to he easfly rotated, turned, pivot and/or tilted so that the jumper shoe 6c may be easily removed.

100421 In further embodiments, the magnets 19 may be operated awl/or actuated using technology in the machining industry for holding workpicces in place, for example hut not limited to, magnetic chucks, magnetic vices and/or magnetic clamps etc. commonly found on grinding machines, pillar drills, lathes and/or milling machines. k this embodiment, the magnets 19 may be permanent magnets and/or electro-magnets, which allows the jumper

S

shoe 6c to easily attached and removed from the electrical conductor rail 7 with a simple lever (not shown) 100431 In embodiments where electro-magnets are used, a part and/or portion of the jumper shoe ôc may he partially magnetised to aIow ease of positioning of the jumper shoe 6c on to the electncal conductor rail 7.

100441 In a further embodiment (not shown), the jumper shoe may bc removably secured to the electrical conductor rail 7 with mechanical means, such as chucks, vices and/or damps etc. 100451 Furthermore, at least the jumper lead 3c, jumper shoe 6c and/or its connector may be provided with markings, colour coding and/or location means to indicate the polarity of the current andlor voltage.

100461 In can he envisaged that the use of magnetic means and/or mechanical means to removably secure the jumper shoe 6c to electrical conductor rail 7 increases the stability of the jumper shoe Oc in-situ, unlike the prior art arrangement that relies on the combination of the operator holding the jumper lead 3a, 3b and the weight. of the jumper shoe 6a, 6b. Since the jumper shoe ôc of the present invention may not require weight to hold the jumper shoe 6c in-situ, it can be envisaged that its housing S may be made from a lightweight, material andlor construction, which may improve the occupational health of the operator.

Alternative Embodiments 100471 It is evident that the full scope and combination of embodiments is extensive; however it is envisaged that the skilled person, having read the description herein, will he able to transfer solutions between the embodiments to meet the specific problems of individual appliances within the scope of the present invention.

100481 The embodiments described above are illustrative of rather than limiting to the present invention. Alternative embodiments apparent on reading the above description may nevertheless fall within the scope of the invention.

Claims

CLAIMS: I. A power cable comprising a first connector at one end for electrical connection to a corresponding connector on an electrically powered carriage, and a second connector having a contact portion at the other end, the contact portion being arranged to be electrically connected and removably secured to an electrical conductor rail.
2. The power cable of daim 1, wherein the contact portion is removably securahlc or secured to the electrical conductor rail by magnetic means.
3. The power cable of claim 2, wherein the magnetic means is electrically insulated, so that the magnetic means do not form part of a current path.
4. The power cable of claim 3, wherein the magnetic means is coated or treated with an electrically insulated material or coating.
5. The power cable of any one of claims 2 to 4, wherein the magnetic means is embedded, housed, resident and/or integrated into the contact portion.
6. Thc powcr cable of any onc of claims 2 to 5. whcrein thc magnetic mcans compriscs electro-magnetic means.
7. The power cable of any one of claims 2 to 5. wherein the magnetic means comprises permanent magnetic means.
8. The power cable of claim 7. further comprising a user actuator operable to detach the permanent magnetic means away from the dectrical conductor rail, such that the contact portion is removably secured to the electrical conductor rail.
9. Thc power cable of claim 7. further comprising means to allow a user to tilt, pivot, turn and/or rotate the contact portion, such that the contact portion can be detached from the electrical conductor rail.
10. The power cable olclaim 9, wherein the means comprises an insulated handle.
11. The power cable of claim 10, wherein the insulated handle is positioned andlor secured to the side of the dectrical connector.
12. The power cable of any one of claims 2 to 11, wherein the magnetic means are provided by a pthrali(y of discrete magnets.
13. The power cable of claim 12, wherein the orientation/positioning and/or the quantity of the discrete magnets is arranged to suit different profiled rails, rail types and/or to adjust the magnetic attraction force.
14. The power cable of claim 1, wherein the contact portion is removably securable or secured to (lie electrical conductor rafi by mechanical means.
15. The power cable of claim 14, wherein (lie mechanical means comprises a clamp, chuck and/or vice or the like.
16. The power cable of any preceding claim, wherein the power cable enters (lie second connector in a direction substantially parallel to the electrical conductor rail when removably secured thereto.
17. The power cable of any preceding claim, wherein the second connector further comprises a housing for said contact portion.
18. The power cable of claim 17, wherein the housing comprising an ethngate horizontal member with a downwardly extending member disposed on each side of the elongate horizontal member to define a channel therebetween for receiving the electrical conductor rail, whereby the contact portion is positioned on the elongate horizontal member.
19. The power cable of claim 17 or 18, wherein the housing is made from a non-ferrous metal or alloy, polymer, composite and/or plastics.
20. The power cable of any preceding claim, wherein the contact portion is made from copper or copper alloy.
21. The power cable of any preceding claim, wherein the contact portion is made from a non-magnetic material.
22. The power cable of any preceding claim, wherein the contact portion is plated with a corrosion resistant material.
23. The power cable of any preceding claim, wherein at least the first connector, second connector andlor power cable is provided with markings. colour coding and/or location means to indicate the polarity of the current and/or voltage.
24. A power cable substantially as herein described with reference to the accompanying Figures.
25. A set of jumper leads comprising at least two power cables, each as claimed in any preceding claim.
26. A set ol jumper leads substantiafly as herein described with reference to the accompanying Figures.

It)
27. An electrical connector comprising a housing having a contact portion arranged to he electrically connected and removably secured to an electrical conductor rail and a terminal portion to be connected to a power cable.
28. The electrical connector of claim 27, wherein the contact portion is removably secured to the electrical conductor rail by magnetic means.
29. The electrical connector ol daim 28. wherein the magnetic means is electrically insulated so that the magnetic means do not form part of a current path.
30. The elcctrical connector of claim 29, wherein the magnetic means is coated or treated with an electrically insulated material or coating.
31. The electrical connector of any one of claims 28 to 30, wherein the magnetic means is embedded, housed, resident and/or integrated into the contact portion.
32. The electrical connector of any one of daims 28 to 31, wherein the magnetic means comprises electro-niagnetic means.
33. The electrical connector of any one of daims 28 to 31, wherein the magnetic means comprises permanent magnetic means.
34. The electrical connector of claim 33. further comprises a user actuator operable to detach the permanent magnetic means away from the electrical conductor rail, such that the contact portion is removably secured to the electrical conductor rail.
35. The electrical connector of claim 33, further comprising means to allow a user to tilt, pivot, turn and/or rotate the contact portion, such that the contact portion can be detached from the electrical conductor rail.
36. The electrical connector oldaim 35, wherein the means comprises an insu'ated hand'e.
37. The dectrical connector of claim 36. wherein the insulated handle is positioned and/or secured to the side of the electrical connector.

It)
38. The dectrical connector of any one of daims 28 to 37, wherein the magnetic means comprises a plurality of discrete magnets.
39. The electrical connector of claim 38, wherein the orientation/positioning and/or the quantity of the discrete magnets is ananged to suit different profiled rails, rail types and/or to adjust the magnetic attraction force.
40. The electrical connector of daim 27, wherein the contact portion is removably securable or secured to the electrical conductor rail by mechanical means
41. The electrical connector of claim 40, wherein the mechanical means comprises a clamp, chuck and/or vice or the like.
42. The electrical connector of any one of claims 27 to 41, wherein the power cable enters the second connector in a direction substantially parallel to the electrical conductor rail when removably secured thereto.
43. The electrical connector of any one of daims 27 to 42, further comprising a downwardly extending member disposed on each side of the elongate horizontal member to define a channel therebetween for receiving the electrical conductor rail, whereby the contact portion is positioned on the dongate horizontal member.
44. The electrical connector of any one claims 27 to 43, wherein the contact portion is made from copper or copper alloy.
45. The electrical connector of any one claims 27 to 44, wherein the contact portion is made Irom a non-magnetic material.
46. The electrical connector of any one claims 27 to 45. wherein the contact portion is plated with a corrosion resistant material.
47. The electrical connector of any one claims 27 to 46. wherein at least the connector and/or power cable is provided with markings, colour coding and/or location means to indicate the polarity of the current and/or vollage.
48. An electrical connector substantially as herein described with relerence to the accompanying Figures. It)Amendments to the claims have been filed as foHows CLAIMS: 1. A power cable for providing electrical power to a railway carriage. the power cable comprising a first connector at one end for electrical connection to a corresponding connector on the railway carriage, and a second connector having a contact portion at the other end, the contact portion being arranged to be electrically connected and removably secured to an electrical conductor ground rail.2. The power cable of claim 1, wherein the contact portion is removably securable or secured to the electrical conductor rail by magnetic means.3. The power cable of claim 2, wherein the magnetic means is electrically insulated, so that the magnetic means do not form part of a current path. IC)4. The power cable of claim 3, wherein the magnetic means is coated or treated with an electrically insulated material or coating.5. The power cable ol any one of claims 2 to 4. wherein the magnetic means is embedded, o 15 housed, resident and/or integrated into the contact portion.6. The power cable of any one of claims 2 to 5. wherein the magnetic means comprises electro-magnetic means.7. The power cable of any one of claims 2 to 5. wherein the magnetic means comprises permanent magnetic means.8. The power cable of claim 7, further comprising a user actuator operable to detach the permanent magnetic means away from the electrical conductor rail, such that the contact portion is removably secured to the electrical conductor rail.9. Thc power cable of claim 7. further comprising means to allow a user to tilt, pivot, turn and/or rotate the contact portion, such that the contact portion can be detached from the electrical conductor rail.10. The power cable of claim 9, wherein the means comprises an insulated handle.11. The power cable of claim 10, wherein the insulated handle is positioned andlor secured to the side of the dectrical connector.12. The power cable of any oiie ci claims 2 to 11, wherein the magnetic means are provided by a plurality of discrete magnets.13. The power cable of claim 12. whcrein the orientationlpositioning and/or the quantity of the discrete magnets is arranged to suit different profiled rails, rail types and/or to adjust (lie magnetic attraction lorce.14. The power cable ol daim 1, wherein (lie contact portion is removably securable or secured to (lie electrical conductor rafi by mechanical means.It) 15. The power cable ol claim 14, wherein (lie mechanical means comprises a clamp, chuck IC) and/or vice or the like.16. The power cable of any preceding claim, wherein the power cable enters the second o connector in a direction substantially parallel to the electrical conductor rail when LCD removably secured thereto.17. The power cable ol any preceding daim, wherein the second connector further comprises a housing for said contact portion.18. The power cable of claim 17, wherein the housing comprising an elongate horizontal member with a downwardly extending member disposed on each side of thc elongate horizontal member to define a channel therebetween for receiving the electrical conductor rail, whereby the contact portion is positioned on the elongate horizontal member.19. The powcr cable of claim 17 or 18. wherein the housing is made from a non-ferrous metal or alloy, polymer, composite and/or plastics.20. The power cable of any preceding claim, wherein the contact portion is made from copper or copper alloy.21. The power cable of any preceding claim, wherein the contact portion is made from a non-magnetic material.22. The power cable of any preceding claim, wherein the contact portion is plated with a corrosion resistant material.23. The power cable of any preceding claim, wherein at least the first connector, second connector and/or power cable is provided with markings. colour coding and/or location means to indicate the polarity of the current and/or voltage.24. A power cable substantially as herein described with reference to and/or as shown in Figures 4 to 9 ol the accompanying Figures.25. A set ol jumper leads comprising at least two power caNes, each as claimed in any preceding claim.It) 26. An electrica' connector substantially as herein described with reference to and/or as shown in Figures 4 to 8 of the accompanying Figures.27. Use of thc cable as claimed in any one of claims 1 to 24, for providing electrical power o to a stranded railway carriage by connecting the first connector to the carriage and the IC) second connector to the ground rail.