GB2124569A - Vehicle electrical power supply arrangement - Google Patents

Abstract

A vehicle e.g. for use in coal mines, chemical or petrol refining works or in corrosive atmospheres has a pantograph (3) which moves a movable connector blade (13) into engagement with discrete conductor elements (8) supported adjacent a linear conductor (1) and biassed away from it by elastomer (7). The blade (13) serially forces the elements (8) into contact with the conductor (1) to give an electrically conductive path to a vehicle carrying the pantograph. The arrangement can be purged by gas fed through ducts (12, 13) to exclude dirt, moisture and other contaminants. <IMAGE>

Description

SPECIFICATION Electrical power supply arrangement This invention relates to electrical power supply arrangements and is particularly, but not exclusively, applicable to arrangements for use in hazardous atmospheres and hostile environments.

There are many known arrangements for collecting electrical power from a linear conductor to a mobile vehicle. The most common is that used in electrical trolley 'buses or railway trains where a pantograph carried by a vehicle is biassed into contact with an overhead wire which carries electric current.

Some railway and transport systems use a collector which depends underneath the vehicle or from its side to pick up current from a ground located linear electrical conductor. This type of system is also used in industrial applications where trailing supply cables to machinery are impractical and where a collector running along a 'bus-bar is more easy to apply.

In most applications the voltages at which the power supply systems work are high enough to be very dangerous to personnel if they inadvertently come in contact with them. For D.C. traction purposes voltages of 66G volts are often used whilst A.C. traction can use voltages of up to 11 Kv. These high voltages mean that the systems have to be highly secured and protected to guard against accidents.

One problem associated with the use of travelling pantographs and collectors is that, particularly at joints in the linear conductor, sparking can occur. This is often made worse in exposed conditions where atmospheric and climatic conditions can accentuate the problern.

Normally this does no harm other than cause pitting and wear of the travelling collector elements which eventually have to be replaced.

However, in certain locations such as in chemical or petrol refining works or in coal mines, there is an incipient risk of explosion due to the nature of the ambient atmospheric conditions and it is not possible to use this type of supply arrangement at anything but the lowest of voltages.

Furthermore, some atmospheres can be corrosive and this means that the linear conductor can either become worn away by the atmosphere or suffer forms of corrosion which irr pairs th - electrical conductivity of any connection made by a pantograph.

In many coal mining applications the risk of explosion from methane given off during the coal mining operations and corrosion due to the damp atmosphere has meant that the use of pantographs collecting from linear conductors to power working mining machinery or transport in tunnels has been impossible.

Suggestions have been made for example as disclosed in British Patent Specification Nos.

1,508,785; 1,508,786 and 1,508,788 to overcome these problems as far as mining machinery is concerned by laying electrical 'busbars along the side of a conveyor on which a mining machine travels so that a collector on the machine can run along the 'bus-bars and pick up current from them. The 'bus-bars are housed in a linear chamber having a flexible seal on one side through which the collector projects and air or an inert gas is used to purge the chamber. It has been found in practice that this system is not totally suitable for the harsh environments of some mines and that corrosion and the risk of sparking still occurs. Furthermore, it has not been found possible to adapt the system for trolleys using an overhead pantograph.

It is an object of the present invention to provide an improved electrical power supply arrangement of the kind in which a collector moves along and collects power from a linear electrical conductor and which is able to be adjusted for use in hazardous and hostile environments without detriment to the linear conductor, the collector or to the efficiency of the collection.

According to a first aspect of the present invention an electrical power supply arrangement comprises a linear electrical conductor and a plurality of discrete conductor elements disposed parallel to and spaced along and from the linear conductor, each element being mounted for individual movement into and out of electrical contact with the linear conductor, and a movable electrical connector arranged for movement parallel to the lienar conductor and having means for moving individual of the said conductor elements into engagement with the linear conductor.

The linear conductor and the discrete conductor elements are preferably contained within a common housing extending longitudinally of the conductor. The housing may have an aperture along one side through which the movable electrical connector extends into the housing, to engage the conductor elements. The aperture is preferably self sealing.

The housing is preferably pressurised by air or an inert atmosphere such as nitrogen and the movable connector advantageously is supplied with the air or gas through passageways in the movable connector. In order to minimise the leakage of air or gas from the arrangement a sealing device, preferably in the form of a labyrinth seal may be provided on the movable connector where it engages with the housing. The movable connector may be provided at two ends with means for increasing the sealing effect of the air or gas.

The discrete connector elements are preferably biassed from the linear conductor, this biassing may be achieved by the use of an elastomer supporting the said elements. The elastomer may substantially fill the housing and also be used to position the linear conductor in the housing, and the elastomer may define a sealed envelope between the conductor and the elements. Each envelope may thus form a unit length and be suitably connected end-to-end with adjacent envelopes to give a continuous linear construction.

The discrete elements may be positioned below the linear conductor and be allowed to fall from the linear conductor by gravity after the movable connector has lost engagement with them.

Pressure sensing means may be incorporated in the system to detect for air or gas leaks.

According to a second aspect of the present invention a method of making a connection to an electric power supply arrangement of the kind incorporating a linear conductor and a movable electrical connector comprises serially moving with the movable connector intermediate discrete conductor elements spaced along the linear conductor into electrical connection with the linear conductor to give an electrical path between the linear conductor and the movable connector through the discrete element.

The movable connector may be arranged to move a plurality of elements into connection with the linear conductor at any one time.

Advantageously the invention includes supplying air or an inert gas at a pressure above ambient to a housing enclosing the linear conductor and the discrete conductor elements.

The method may also include biassing the said elements away from the linear conductor and out of connection therewith when the movable conductor is not in the area of the discrete elements.

In order that the invention may be fully understood one example of an electrical supply arrangement in accordance therewith and using the method thereof will now be described with reference to the accompanying schematic drawings.

In the drawings: Figure 1 shows a locomotive connected to a section of an overhead conductor; Figure 2 shows a cross-section through the conductor and the conductor box; and Figure 3 shows the conductor box in an isometric view.

In this application of the invention the invention is used in connection with the supply of electricity from an overhead conductor to an electric locomotive operating in the tunnel of a coal mine.

The coal mine is likely to contain methane gas to a small extent and thus any risk of incendive sparking which might give rise to an explosion has to be reduced. Also the atmosphere is likely to contain dust, grit and moisture which can considerably affect the wear and conductivity of sliding electrical parts.

Referring now to the drawings, these show a linear conductor which extends along the roof of a tunnel in a coal mine and which is used as a source of traction power to an electrically powered locomotive 2. The locomotive 2 has a pantograph 3 which connects to a collector box 4 and current collected at the collector box 4 is fed through the pantograph arm to the locomotive power unit.

In order to keep out dirt and moisture the conductor 1 is contained within a channel shaped housing 5 of metal or a suitable non-static plastics material. The cross-section of the housing shown in Figure 2 clearly shows a pair of flexible lips 6 which are normally biassed together to form a seal. The conductor and housing and housing are supplied in unit length with the ends appropriately joined.

The conductor 1 is positioned in housing 5 by an elastomer 7 which surrounds the conductor 1 except on its lower side. Below the conductor 1 and also secured by the elastomer 7 is a linear series of discrete connector elements 8 spaced by a small gap 9 from conductor 1 and closely spaced end-to-end but electrically separated from each other. The elastomer 7 is formed with gaps 10 which assist in flexing of the elastomer in operation. The gaps 9 and 10 are within a sealed envelope formed by the elastomer 7 and elements 8. The gaps support an inert gas atmosphere, in this example nitrogen, but in other examples air or a vacuum may be present.

The collector box 4 is made of electrically insulating material but has a central blade-like conducting element 11 which extends above the level of the box through the seal 6 to engage the underside of elements 8 and make an electrical contact therewith. A passageway 12 with outlet ducts 1 3 is formed in the connector box 4 and the element 11 and a n;trogen purging gas is fed under pressure of about 3 atmospheres through the passageway and ducts to the interior of the housing 5 in the area underside of the elements 8 and the conducting element 22 in operation. A pressure sensor 14 for the gas is incorporated into the box 4 (Figure 3) and other sensors can be incorporated in the housing 5 to ensure that there is no loss of pressure during working of the arrangement.

As can be seen from Figure 2 a labyrinth hair seal 1 5 is provided around the mating edge of box 4 and the housing 5 to reduce pressure loss and to give a flexible sliding seal. Collector boxes 1 6 containing pressured gas are fitted to either end of box 4 to assist in keeping the system free from gas leaks.

In operation the conductor 1 has a potential applied to it and the elements 8 are normally biassed out of contact with it by the elastomer 7, as the locomotive 2 approaches the pantograph 3 biasses the box 4 upwards and the blade 11 forces open the lips 6 and makes contact with one or more elements 8. The pressure from the pantograph pushes the elements 8 upwards against the resistance of the elastomer 7 so that an electrical connection is made from conductor 1 through an element 8, blade 11 and pantograph 3 to the locomotive 2. As the locomotive moves along elements 8 are serially brought into contact with the conductor 1 and when the blade 11 moves out of contact they revert under the biassing action of the elastomer 7 to their normal position. All the time gas is fed through passageway 12 and ducts 13 to keep the housing pressurised. The blade 11 is of sufficient length that there will always be at least one element 8 in contact with the conductor 1.

The use of the elements 8 ensure that there is always a clean contact surface to make contact with the conductor 1 and since the contact area is in a sealed envelope filled with an inert gas no incendive sparking will occur. Also, since the gas pressure is above ambient no methane, dirt or moisture will be able to enter the connector area to damage the contacts. The blade 11 gives a wiping contact with the underside of the elements 8 to ensure a self cleaning action.

It will be appreciated that in safe atmospheres the sealed envelope may not be necessary and also that the elastomer support for the elements 8 can be dispensed with and they could be allowed to separate from the conductor 1 by gravity.

In this example the disposition of elements 8 is below conductor 1 there is no limit to this disposition and the housing 5 can be arranged on its side or upside-down from the position shown if the application of the invention requires the entry from the pantograph to be other than from below.

Claims (24)

1. An electrical power supply arrangement comprising a linear electrical conductor and a plurality of discrete conductor elements disposed parallel to and spaced along and from the linear conductor, each element being mounted for individual movement into and out of electrical contact with the linear conductor, and a movable electrical connector arranged for movement parallel to the linear conductor and having means for moving individual of the said conductor elements into engagement with the linear conductor.

2. An arrangement as claimed in claim 1, in which the linear conductor and the discrete conductor elements are housed within a common housing extending longitudinally of the linear conductor.

3. An arrangement as claimed in claim 2, in which the housing has an aperture along one side through which the movable electrical connector is arranged to extend into the housing to engage the conductor elements.

4. An arrangement as claimed in claim 3, in which the aperture is self-sealing.

5. An arrangement as claimed in claim 2, 3 or 4 in which air or gas is supplied to the housing under pressure.

6. An arrangement as claimed in claim 5, in which the air or gas is supplied through passageways in the movable electrical connector.

7. An arrangement as claimed in claim 5 or 6 and including gas pressure sensing means.

8. An arrangement as claimed in any one of claims 5, 6 or 7, in which a labyrinth seal is provided between the movable electrical connector and the housing.

9. An arrangement as claimed in any one of claims 6, 7 or 8 and including gas pressure means at either end of the movable electrical connector for increasing the sealing effect of the air or gas.

10. An arrangement as claimed in any one of claims 6 to 9 in which the gas is an inert gas.

1 An arrangement as claimed in any preceding claim and including means for biassing the discrete connector elements from the linear conductor.

12. An arrangement as claimed in claim 11 in which the biassing means is an elastomer.

13. An arrangement as claimed in claim 11 in which the elastomer substantially fills the or a housing in which the conductor and elements are contained and positions the conductor and elements in the or a housing and the elastomer defines a sealed envelope between the conductor and the elements.

14. An arrangement as claimed in claim 11 in which the discrete conductor elements are positioned freely below the linear conductor and are biassed away from the conductor by gravity.

1 5. An arrangement as claimed in any preceding claim in which the movable electrical conductor includes a mounting device carrying a conductive contact arranged in use to slide along the discrete elements and force them into contact with the linear conductor.

1 6. An arrangement as claimed in claim 15 in which the conductive contact has a length such that it is able to force at least two of the said elements into contact with the linear conductor at any one time.

17. An arrangement as claimed in claim 1 5 or claim 1 6 and including pivotal mounting means for connecting the connector to a movable vehicle and the discrete elements.

1 8. An electrical power supply arrangement substantially as hereinbefore described with reference to the accompanying drawings.

1 9. A method of making a connection to an electric power supply arrangement of the kind incorporating a linear conductor and a movable electrical connector comprises serially moving with the movable connector intermediate discrete conductor elements spaced along the linear conductor into electrical connection with the linear conductor to give an electrical path between the linear conductor and the movable connector through the discrete elements.

20. A method as claimed in claim 19 in which the movable connector is arranged to move a plurality of elements into connection with the linear conductor at any one time.

21. A method as claimed in claims 19 or 20 and including supplying a gas at a pressure above ambient to a housing enclosing the linear conductor and the discrete conductor elements.

22. A method as claimed in claim 21 including sealing the housing with a flexible seal against loss of gas pressure.

23. A method as claimed in any of claims 20 to 22 including biassing the said elements away from the linear conductor and out of connection therewith when the movable conductor is not in the area of the discrete elements.

24. A method of making a connection to an electric power supply arrangement substantially as hereinbefore described.