How does railway electrification work

Semaphore signalling system is being replaced by color light signalling system. Use of color light signals results in better visibility of signaling aspects to the loco pilots of running trains and this makes train running safer and operationally efficient. Inter-locking system is also being changed to panel or route relay interlocking.

Besides speedier movement of traffic, these up-gradation measures contribute towards increase in safety. Underground cables are provided along with electrification, which results in more reliable and better quality of communication. In the present day electrification projects, state-of-the-art microprocessor based supervisory control and data acquisition system SCADA is being provided as against the earlier electro-mechanical strowger system of remote control equipment.

The SCADA system has facilities for tele-metering of voltage, current, maximum demand and power factor on a real time basis which enables control of maximum demand and thereby the charges thereof to be paid to the State Electricity Boards. In addition, this system provides for automatic trouble shooting and isolation of faulty section.

With this system the advantage of high voltage transmission, i. This is achieved by an additional power conductor on top of the overhead equipment and the mast with 50 kV being obtained between the overhead equipment and the feeder. In addition, use of return conductor and booster transformers is eliminated completely. Traction Sub-Station. As part of the modernization plan, Indian Railways had imported eighteen 18 Horse Power Thyristor Locomotives, with transfer of technology.

This cable is free from copper and is, therefore, not prone to theft. It provides superior quality of communication with built in large number of telephone channels to meet future needs of train operation and safety.

Railroad operators in many other industrialized countries chose to switch to electric locomotives, partly because the railroads were owned by the governments of those countries, which could better afford the necessary transmission infrastructure. As a result, electrified rail is currently used on less than 1 percent of U. The California commuter rail line CalTrain is currently being upgraded to very high speed rail VHSR service and will use electric power. Other electric VHSR systems which would be electric-powered are also being considered around the country, but do not yet have funding.

Making the transition from the current U. It does, however, point out that many other nations Switzerland, Sweden, the Netherlands, Italy, France, Germany, Russia, China, India, Japan… have made significant moves to electrify their railway systems, and many other countries are now engaged in efforts to do so.

However, it is easier for those countries to secure financing for major infrastructure investments like this than it is for their U. The U. The large investment necessary is an obvious obstacle, and the interest in reducing the nation's carbon footprint by switching to electric rail is not strong in Congress. Such an effort would be more difficult in this country than in Europe or Asia, which have more dense urban populations. While several other technologically-advanced nations e.

Some point to public-private partnerships PPPs as a way to fund an electrified rail network by using a combination of federal, state, private sector, and possibly regional, funding. The electrification of freight rail could start with a demonstration project along the Northern Corridor, which runs from Seattle to Chicago connecting several cities and towns along the way.

Modern systems link the traction current status to the signalling so that a train will not be allowed to proceed onto a dead section. Diagram: Author. At various points along the line, there will be places where trains can be temporarily isolated electrically from the supply system. At such places, like terminal stations, "section switches" are provided. When opened, they prevent part of the line for being fed by the substation. They are used when it is necessary to isolate a train with an electrical fault in its current collection system.

This is about its limit for speed and has only spread over such a large area for historical reasons. What about the electrical return? There has to be a complete circuit, from the source of the energy out to the consuming item light bulb, cooking stove or train and back to the source, so a return conductor is needed for our railway. Simple — use the steel rails the wheels run on. Provided precautions are taken to prevent the voltage getting too high above the zero of the ground, it works very well and has done so for the last century.

Of course, as many railways use the running rails for signalling circuits as well, special precautions have to be taken to protect them from interference. The power circuit on the train is completed by connecting the return to brushes rubbing on the axle ends. The wheels, being steel, take it to the running rails. These are wired into the substation supplying the power and that does the job. The same technique is used for DC or AC overhead line supplies.

Figure 7: Presentation by the Schunk Group showing how an electric traction supply system ensures an earth return system gets grounded to the running rails to complete the traction power circuit.

Video time is 1m 26s. AC or DC traction. You just need to put the right sort of control system between the supply and the motor and it will work. However, the choice of AC or DC power transmission system along the line is important.

It can be summarised simply as AC for long distance and DC for short distance. Of course there are exceptions and we will see some of them later.

It is easier to boost the voltage of AC than that of DC, so it is easier to send more power over transmission lines with AC. This is why national electrical supplies are distributed at up to , volts AC. As AC is easier to transmit over long distances, it is an ideal medium for electric railways. Only the problems of converting it on the train to run DC motors restricted its widespread adoption until the s.

DC, on the other hand was the preferred option for shorter lines, urban systems and tramways. However, it was also used on a number of main line railway systems, and still is in some parts of continental Europe, for example. Apart from only requiring a simple control system for the motors, the smaller size of urban operations meant that trains were usually lighter and needed less power. Of course, it needed a heavier transmission medium, a third rail or a thick wire, to carry the power and it lost a fair amount of voltage as the distance between supply connections increased.

This was overcome by placing substations at close intervals — every three or four kilometres at first, nowadays two or three on a volt system — compared with every 20 kilometres or so for a 25 kV AC line. It should be mentioned at this point that corrosion is always a factor to be considered in electric supply systems, particularly DC systems.

The tendency of return currents to wander away from the running rails into the ground can set up electrolysis with water pipes and similar metallics. Overhead Line Catenary. The mechanics of power supply wiring is not as simple as it looks Figure 1. Hanging a wire over the track, providing it with current and running trains under it is not that easy if it is to do the job properly and last long enough to justify the expense of installing it.

Overhead catenary systems, called "catenary" from the curve formed by the supporting cable, have a complex geometry, nowadays usually designed by computer. The contact wire has to be held in tension horizontally and pulled laterally to negotiate curves in the track.

The contact wire tension will be in the region of 2 tonnes. The wire length is usually between and metres long, depending on the temperature ranges. The wire is zigzagged relative to the centre line of the track to even the wear on the train's pantograph as it runs underneath. The contact wire is grooved to allow a clip to be fixed on the top side Figure 8. The clip is used to attach the dropper wire.

The tension of the wire is maintained by weights suspended at each end of its length. Each length is overlapped by its neighbour to ensure a smooth passage for the "pan". Incorrect tension, combined with the wrong speed of a train, will cause the pantograph head to start bouncing. Weare a Core Part I approved vendor to manufacture and supply all type of Railway Electrification structures like portals, masts, beams, gantries, small parts steel, sub-station structures and customized structures as well.

How Does Railway Electrification Work?