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ELECTRIC LOCOMOTIVES An electric locomotive is a locomotive powered by electricity from overhead lines , a third rail or an on-board energy storage device such as a chemical battery or fuel cell .


INTRODUCTION Electricity is used to eliminate smoke and take advantage of the high efficiency of electric motors; however, the cost of railway electrification means that usually only heavily-used lines can be electrified. the power for electric locomotives can come from clean and/or renewable sources , including geothermalpower , hydroelectric power , nuclear power , solar power and wind turbines . Electric locomotives benefit from the high efficiency of electric motors, often above 90%. Additional efficiency can be gained from regenerative braking , which allows kinetic energy to be recovered during braking to put some power back on the line. Newer electric locomotives use AC motor-inverter drive systems that provide for regenerative braking.




HISTORY The first known electric locomotive was built by a Scotsman , Robert Davidson of Aberdeen in 1837 and was powered by galvanic cells ('batteries'). The first electric passenger train was presented by Werner von Siemens at Berlin in 1879. The locomotive was driven by a 2.2 kW motor and the train, consisting of the locomotive and three cars, reached a maximum speed of 13 km/h. The first use of electrification on a mainline was on a four-mile stretch of the Baltimore Belt Line of the Baltimore and Ohio Railroad (B&O) in 1895. In the 1930s, the Pennsylvania Railroad , which also had introduced electric locomotives because of the NYC regulation, electrified its entire territory east of Harrisburg, Pennsylvania .


ELECTRIC LOCOMOTIVES Electric locomotive of the Baltimore Belt Line , 1895. AC locomotive in Valtellina (1898-1902). Power supply: 3-phase 15 Hz AC, 3000 V.




TYPES OF ELECTRIC LOCOMOTIVES Rechargeable energy storage systems , as battery or ultracapacitor powered mining locomotives. A stationary source, such as a third rail or overhead wire . This is in marked contrast to a diesel-electric locomotive , which combines an onboard diesel engine with an electrical power transmission or store (battery, ultracapacitor) system. The type of electrical power used, either alternating current or direct current . The method for store (batteries, ultracapacitors) or collecting (transmission) electrical power. The means used to mechanically couple the traction motors to the driving wheels (drivers).


DC AND AC CURRENT The most fundamental difference lies in the choice of direct (DC) or alternating current (AC). Direct current locomotives typically run at relatively low voltage (600 to 3,000 volts); the equipment is therefore relatively massive because the currents involved are large in order to transmit sufficient power. Power must be supplied at frequent intervals as the high currents result in large transmission system losses. AC traction seldom uses two-phase lines in place of single phase lines. The transmitted three-phase current drives induction motors , which do not have sensitive commutators and permit easy realisation of a regenerative brake . Speed is controlled by changing the number of pole pairs in the stator circuit and by switching additional resistors in the rotor circuit.


POWER TRANSMISSION A modern pantograph . The device shown is technically a half-pantograph. Electrical circuits require two connections (or for three phase AC , three connections). From the very beginning, the trackwork itself was used for one side of the circuit. Unlike model railroads , however, the trackwork normally supplies only one side, the other side(s) of the circuit being provided separately. However, railways generally tend to prefer overhead lines , often called " catenaries " after the support system used to hold the wire parallel to the ground. Three collection methods are possible: Trolley pole : a long flexible pole, which engages the line with a wheel or shoe. Bow collector : a frame that holds a long collecting rod against the wire. Pantograph : a hinged frame that holds the collecting shoes against the wire in a fixed geometry. Of the three, the pantograph method is best suited for high-speed operation. Some locomotives are equipped to use both overhead and third rail collection (e.g. British Rail Class 92 ).


DRIVING THE WHEELS Early locomotives used often jackshaft drives. In this arrangement, the traction motor is mounted within the body of the locomotive and drives the jackshaft through a set of gears. This system was employed because the first traction motors were too large and heavy to mount directly on the axles. Another drive example was the "bi-polar" system, in which the motor armature was the axle itself, the frame and field assembly of the motor being attached to the truck (bogie) in a fixed position. The motor had two field poles, which allowed a limited amount of vertical movement of the armature. This system was of limited value since the power output of each motor was limited. Modern electric locomotives, like their Diesel-electric counterparts, almost universally use axle-hung traction motors, with one motor for each powered axle.


WHEEL ARRANGEMENT The Whyte notation system for classifying steam locomotives is not adequate for describing the varieties of electric locomotive arrangements, though the Pennsylvania Railroad applied classes to its electric locomotives as if they were steam or concatenations of such. In any case, the UIC classification system was typically used for electric locomotives, as it could handle the complex arrangements of powered and unpowered axles and could distinguish between coupled and uncoupled drive systems.


ELECTRIC TRACTION AROUND THE WORLD JAPAN The rail system of Japan consists of the following (as of 2005): 20,264 km (12,591 mi) of 1,067 mm (42.0 in) Cape gauge , of which 13,280 kilometres (8,250 mi) is electrified; 3,204 km (1,991 mi) of 1,435 mm (56.5 in) standard gauge , all electrified; 117 km (73 mi) of 1,372 mm (54.0 in) Scotch gauge , all electrified; 11 km (6.8 mi) of 762 mm (30.0 in) narrow gauge , all electrified. Electrification systems used by the JR group, Japan's formerly state owned operaters, are 1,500V DC and 20kV AC for conventional lines and 25kV AC for Shinkansen. Electrification with 600V DC and 750V DC are also seen in private lines. The frequency of the AC power supply is 50 Hz in Eastern Japan and 60 Hz in Western Japan. MALAYSIA Keretapi Tanah Melayu of Malaysia operated 25 kV AC electric multiple unit services, starting from their KTM Komuter in 1995. In December 2009, a fleet of new ETS are arrived.

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AUSTRALIA Both VictorianRailways and NewSouthWales Government Railways , which pioneered electric traction in Australia in the early 20th century and continue to operate 1,500 V DC Electric Multiple Unit services, have withdrawn their fleets of main line electric locomotives. Queensland Rail , conversely, implemented electrification relatively recently and utilises the more recent 25 kV AC technology with around 1,000 km of the QR narrow gauge network now electrified. It operates a fleet of electric locomotives to transport coal for export, the most recent of which are those of the 3,000 kW (4,020 HP) 3300/3400 Class. EUROPE Electrification is widespread in Europe. Due to higher density schedules, the operating costs of the locomotives are more dominant with respect to the infrastructure costs than in the US and electric locomotives have much lower operating costs than diesels. For instance, the 2,200 kW of a modern British Rail Class 66 were already met in 1927 by the electric SBB-CFF-FFS Ae 4/7 (2,300 kW), which is even a bit lighter. CANADA No railways in Canada use electric locomotives on their lines as of January 2011. Agence métropolitaine de transport (AMT) has ordered the ALP-45DP dual mode electro-diesel locomotives for use on the Repentigny-Mascouche Line (AMT) . The locomotives will run as electric while in the Mount Royal Tunnel only and as diesel elsewhere. GO Transit has completed a study on electrifying some of their commuter rail lines (Georgetown/Air Rail Link & Lakeshore), but so far, no target date or purchases have been initiated.

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RUSSIA AND FORMER USSR Russia and other countries of the former USSR have a mix of 3,300 V DC and 25 kV AC electric railroads due to historical reasons. Historically, first the 3,300 V DC wiring was used due to vehicle simplicity. 25 kV AC contact wiring started in the USSR in around 1960, when the industry managed to build the rectifier-based AC-wire DC-motor locomotive . The first major line with AC power was Mariinsk-Krasnoyarsk-Tayshet-Zima; the lines in European Russia like Moscow-Rostov-on-Don followed. UNITED STATES In the United States, only certain dense urban areas and some mountainous areas were electrified and the latter have all been discontinued. In North America, the flexibility of diesel locomotives and the relative low cost of their infrastructure has led them to prevail except where legal or other operational constraints dictate the use of electricity. An example of the latter is the use of electric locomotives by Amtrak and commuter railroads in The Northeast (e.g. New Jersey Transit New York corridor uses ALP-46 electric locomotives).

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INDIA In India, both AC and DC type of electrified train systems operate today. A 1,500 V DC-based train system is only operating in the Mumbai area. It is being converted to the 25 kV AC system. The rest of the India, where routes are electrified fully, operate under the 25 kV AC overhead wire. As of 2006, Indian railways haul 80% of freight and 85% of passenger traffic with electric locomotives.


BATTERY LOCOMOTIVES A battery locomotive (or battery-electric locomotive) is a type of electric locomotive powered by on-board batteries; a kind of battery electric vehicle . Such locomotives are used where a conventional diesel or electric locomotive would be unsuitable. Another use for battery locomotives is in industrial facilities – as an alternative to the fireless locomotive – where a combustion-powered locomotive (i.e., steam- or diesel-powered ) could cause a safety issue, due to the risks of fire, explosion or fumes in a confined space.


ADVANTAGES AND DISADVANTAGES 1. According to O-Keating's The Electric Engine, the major advantage of the electric locomotive engine over diesel engine is that electric engine uses a rather simple and straightforward technology. 2. The electric engine pulls power directly from the power grid and requires only a transformer and a regulator to bring down the power to acceptable levels. 3. Electric engines are lightweight, constituting only motors and wheel axles, and have almost no moving parts. 4. The simple nature of the electric engine makes them efficient and powerful. Electric engines do not produce much heat and noise, meaning that most of the energy produces converts into foreword motion. 5. Electric engines are therefore easier to maintain whereas the moving parts of a diesel engine require constant maintenance. 6. A major commercial consideration for railways to prefer electric locomotive engines to diesel locomotive engines is cost and availability of diesel. Diesel is an expensive non-renewable fuel source whereas electricity is a cheaper and infinite source of energy. 7. The major disadvantage of the electric locomotive engine compared to the diesel locomotive engine is the requirement for power supply in the form of overhead electric lines. 8. The capital cost of laying 5 to 6 kilometers of traction wires is equivalent to the cost of a new diesel locomotive. 9. In addition to the cost and difficulties of installing overhead power lines and sub-stations to supply power, the possibility of disruption of train services is always a live concern for the following reasons: power disruption damage to the overhead lines or posts supporting the electric lines The pentograph on top of the locomotive not making proper contact with the electric wires


CONCLUSION Finally, I can conclude that electric locomotives playing a vital role in railway system till now. Electricity is used to eliminate smoke and take advantage of the high efficiency of electric motors; however, the cost of railway electrification means that usually only heavily-used lines can be electrified. The International Railway Journal of March 2000 indicates that the future of the locomotive lies in a simple fuel cell that uses Hydrogen from fuel to combine with Oxygen and produce electricity. Diesel engines an easily upgrade to such a new technology by replacing the engine with the fuel cell, and in such as scenario, the overhead wires used for electric engines would become redundant.



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