Railways – Car-carried propulsion system – Electric
Reexamination Certificate
2002-04-09
2004-08-31
Morano, S. Joseph (Department: 3617)
Railways
Car-carried propulsion system
Electric
C191S002000
Reexamination Certificate
active
06782833
ABSTRACT:
This invention relates to improvements in trackside power distribution systems for railways.
All railway systems include units which are located along the track and which need power either to monitor or control the use of the track. These units include control equipment, which controls the signals spaced at intervals along the track. The signals alert the driver of a train as to whether or not a train can proceed or must stop. Also, where a track branches, points are provided. To change this point automatically, for example using an electric motor, a source of electrical power is needed.
Furthermore many railways include some form of automatic train detection system. This typically involves providing sensors at intervals along the track which monitor sections, or zones, of track. The sensors detect the presence of a train on the tracks. Again, these also require a source of power.
In the past, trackside power distribution has been achieved by passing a low voltage, usually 650 volts, along a copper or aluminium conductor that extends from a source of power known as a signal supply unit to the various loads requiring power (such as control circuits and signals, points motors, train detection systems). A single two-core cable is provided, usually having an aluminium core cable. This may run along the track for several kilometers from the power source and is usually located within a concrete channel to protect it against damage. The various loads draw power from one core of the cable and return it to the source along the other. They are attached to the cable through take off spurs. The more loads that are connected to a cable, the thicker the cable must be. For this reason, the length of cable is limited. To serve a large railway network, several/sources of power are provided along the track, so that between them the whole of the track is supplied with power.
The 650 volt supply is isolated from earth in accordance with provisions in current wiring regulations. The regulations allow the power to remain connected in the event of the conductors becoming connected to earth.
The use of the single feeder cable in the prior art presents several problems. The first, and most important problem is that the reliability of the system is entirely dependent on the integrity of the cable. The cable is often attacked by vandals, or chewed by rodents. If the cable is broken in this way it will prevent the flow of power from the source to any loads downstream of the break.
A further problem arises due to the need to provide high levels of reliability for the signal supply unit. Obviously, it is critical for the safety of a railway that power to signals is maintained even if a fault at the supply occurs. Even for an overspecified signal supply unit a failure of the electricity distribution network to which it is connected will cut-off the supply to the feeder cable.
At present, an acceptable level of reliability is achieved by providing a large back-up generator at the end of the feeder cable nearest the source of power. If the power source fails the generator is adapted to start automatically. The provision of such a large generator is, however, undesirable as it is both costly to maintain and also expensive to install. Generators must be lubricated frequently to ensure they remain reliable (especially when they are normally dormant) and containment for the lubricant must be provided.
A representative example of a prior art trackside signal power distribution system for railways is illustrated schematically in
FIG. 1
of the accompanying drawings.
The portion of track supplied by the system in
FIG. 1
, shown in dashed line, is divided into four sections
1
,
2
,
3
,
4
to form a T-shape. One section
1
defines the centre of the track and extends three ways from the centre of the T. The remaining three sections
2
,
3
,
4
define the extremities of track.
Each section
1
,
2
,
3
,
4
is provided with various units requiring power, in this case small location cases
5
located along the section. The cases located long the centre section of track
1
receive power from one of the three feeder cables
6
a
,
6
b
,
6
c
radiating from a centrally located power supply
10
. The other units
5
receive power supplied along a respective feeder cable
7
,
8
,
9
associated with a respective supply unit
11
,
12
,
13
. Thus, four signal supply units and six feeders are provided in this example. Of these, one supply unit has three feeders
6
a
,
6
b
,
6
c
extending from it such that the supply is effectively located at the centre of a feeder rather than at the ends. The others have one feeder and are therefore located at the end of a section. The choice of location depends largely on the availability of a suitable tap into a regional electricity distribution network and the topoplogy of the signalling system.
Each feeder
6
a
,
6
b
,
6
c
,
7
,
8
and
9
extends for approximately half of the distance between signal supply units and each piece of trackside equipment,
5
receives power from the signal feeder associated with that section.
As illustrated, the trackside equipment for each section includes at least two location units
5
. Also shown is the presence of at least one larger casing in the form of a relocatable equipment building
14
on each section. The relocatable equipment buildings
14
contain an air-conditioning unit to keep the equipment cool. Power for this is taken from a separate tap into an adjacent regional distribution network, although power for the contents and equipment within the relocated equipment building are taken from the feeders.
Each signal supply unit comprises a change over switch
15
that connects the feeder, through an isolation transformer
16
, to the regional electricity distribution network at that point. It is therefore the responsibility of the regional electricity company running the network to supply power to the feeders through the signal supply unit.
In the event of a loss of power from the distribution network, the changeover switch may be operated to isolate the transformer from the network and connect it to a back-up generator
17
. This provides an alternative source of power in the event of a failure.
A problem with such a system is that a fault at any one signal supply unit can cause a complete loss of power to its associated feeder. This is unacceptable for reliability and safety reasons. Another problem occurs if the feeder is severed (for instance by a rodent chewing on the cable or vandalism), resulting in all units downstream of the point at which the cable is severed losing power. The reliability of the back-up generator is also of doubt, depending to a large extent on the quality of maintenance it receives.
An object of the present invention is to ameliorate some of the problems of the prior art systems, and to provide a more reliable trackside power distribution system for railways.
According to a first aspect, the invention provides a trackside power distribution apparatus comprising:
a first signal supply unit having an input adapted to receive power from a first electrical power source and an output for supply of power to a feeder;
a first portion of feeder connected to the output of the first signal supply unit and extending alongside the track to a unit requiring power,
a second signal supply unit having an input adapted to receive power from a second electrical power source and an output for supply of power to a feeder; and
a second portion of feeder connected to the output of the second signal supply unit and extending alongside the track to the said unit requiring power.
The apparatus may further include a selection apparatus adapted to select which feeder portion is used to supply power to the unit.
Units requiring power within the scope of the invention include location cases which house control equipment, for example to control signal lights along the track. Several such location cases may be provided which individually draw power from a feeder portion, or a group of several cases may draw power from a feeder through an intermediate
Alston
Kirschstein et al.
Morano S. Joseph
Olson Lars A.
LandOfFree
Trackside power distribution systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Trackside power distribution systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Trackside power distribution systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3319647