Archive-name: model-railroad-faq/prototypeããThis is part of the rec.models.railroad list of Frequently AskedãQuestions (FAQ).  It is maintained by Ralph Marshallã(rjm@cs.brown.edu) All contributions and corrections are welcome, butãI'm ultimately responsible for what appears here. ããChanges since the last posting:ãããIntroduction to diesel locomotivesã----------------------------------ããQ. I am trying to gain some very basic knowledge about diesel enginesã   so that I can buy the models with some intelligence. Could someoneã   give me the basic rundown of the different classes of dieselã   engines and what they were used for?ãã[This answer was edited from material written by Fred Ochs and laterãaugmented by various readers]ããA. Locomotive manufacturersãã EMD:     Electro-Motive Division of General Motorsã          Before being bought by GM, it was EMC - Electroã          Motive Corporation. ã GE:      General Electricã Alco:    Americal Locomotive Worksã Baldwin: Baldwin Locomotive Worksãã Baldwin Locomotive Works was named after the "founding father"ã Mathias(?) Baldwin. In 1928 the Baldwin works moved fromã Philadelphia to nearby Eddystone, Pa. For a complete story ofã "the works", check the book _The Locomotives that Baldwinã Built_ by Fred Westing pub. 1966 by Superior Publishing Co,ã Seattle Washington, also re-printed by Bonanza Books.ãã Lima:    Lima-Hamiltonã        BLH:     Baldwin,Lima,Hamiltonãã The Lima and Hamilton plants were in towns of the same name inã        Ohio. These companies started out making steam locomotives.ã They never really succeeded in the transition to diesel, andã even after merging eventually went out of business.) ãã MLW:     Montreal Locomotive Worksã The successor to MLW was Bombardier who built some MLW designsã for a while in Canada.  The Montreal MLW/Bombardier plant isã now run (owned?) by GE-Canada.  Bombardier still manufacturesã railroad passenger cars in Barre, VT.ãã        FM:      Fairbanks-Morseã Also note that FM and Baldwin designs were built in Canadaã under license by CLC - Canadian Locomotive Company.ãã Only EMD and GE are still producing railroad locomotives.ããA. A few naming conventions.ããDiesel locomotives are designated by the number of powered axles,ãdivided into trucks.  The letters A,B,C,D stand for 1 through 4 axles,ãso an EMD FT (see below) with 2 trucks each of which contains twoãdriving axles is a B-B. Early locomotives were made with A1A trucks (2ãaxles, the center one unpowered).ããA units have a cab with controls for the engineer.ãB units are basically A units with no controls.ãSlugs are a cut-down frame filled with concrete.  They have onlyã   traction motors, and receive power from an attached engine.ãã****************ãA slightly different convention seems to be in use in Europe,ã    possibly due to the wider range of designs employed:ã****************ããThe number of non-driven axles is determined by an arabic number:ã1 = 1 axle, 2 = 2 axles in one frame, and so on.ããThe number of driven axles is determined by an uppercase letter:ãA = 1 driven axle, B = 2 driven axles in one frame, and so on.ããA small 0 (or o) after an uppercase letter means that each axleãis driven by its own motor.ããParentheses () around letters and numbers indicate they are built intoãone frame or bogie. ããAn apostrophe (') after a number, a letter or a parenthesed expressionãmeans that these axle(s) are situated in a bogie, independent from theãframe.ããIndependent vehicles are separated by a plus (+) sign.ãIf you see something like 2'2'2'2'2'2'.... this is probably anãarticulated train.ããExamples:ã2'C2' = a bogie of two axles, three driven axles in the frame, andã  another bogie of two axlesãBo'Bo' = two bogies, each with two axles, each axle driven by itsã  own motorã(1'C)'(C'1)' = two bogies, each with three axles driven by oneã  motor and one independent axleããA. Names of locomotivesããEMD's first main model was the FT, which stood for FourTeen hundredãhorsepower. (Commonly referred to as "the Diesel That Did It" since itãwas the first practical replacement for mainline steam power.) ããIt had 1350 HP(horse power) They were designed to be semi-permanentlyãcoupled and sold usually as sets. (Initially most railroads numberedãthem as one locomotive with unit designators such as A,B,C,D to getãaround union rules requiring a full crew for each locomotive.) ããThis was followed by the following engines: ã F2A,F2B 1350HPã        F3A,F3B,F7A,F7B,FP7  1500HP ã F9A,F9B,FP9 1750 HP ããThe FP models were intended for passenger service, as they included aãsteam generator at the rear of an extended body.  Passenger equipmentãwas originally built to use steam for heating (since they were pulledãby steam engines with a handy supply of it), so when diesels wereãintroduced separate steam generators had to be added for passengerãservice.  Modern equipment no longer uses steam heat, removing theãneed for extra equipment.ããWe also have the E unit, similar in appearance to the F unit, exceptãit has A1A trucks. They also have 2 diesel engines in them, to give them moreãHP.  ã EA,EB,E1A,E1B,E2A,E2B 1800HPã E3A,E3B,E4A,E4B,E5A,E5B,E6A,E6B,E7A,E7B 2000HP ã E8A,E8B 2250 HP E9A,E9B 2400 HPããBefore making the F7, EMD introduced a new model type, called the BL1ãIt stood for Branch Line, had 1500 HP, and had the same motor that the F7ãand GP7 (which I will explain) did. They followed this by the BL2,ãalthough it is argued what the change was. This engine had most of theãcab style, with notches along each side, that would allow the engineerãto see behind him better. ããThis was followed by the GP7 (and concurrently produced with the F7)ãThe GP series stood for General Purpose, and had walkways along each hood.ãIt camein both passenger and freight versions. Passenger versions had aãsteam generator in the short hood (typically called the nose) to heat theãpassenger cars. This engine had B trucks and 1500 HPãhere is a list of GP style engines:ã GP7 1500 HPã GP9 1750 HPã GP15-1 1500 HPã GP18 1800 HPã GP20,GP28,GP38 2000 HPã GP30 2250 HPã GP39 2300 HPã GP35 2500 HPã GP40, GP40P(*) 3000 HPã GP40X 3500 HPã GP50 3500/3600 HPã GP60 3800 HP  (current model)ããThe next frieght style is the SD series, which stands for Special Duty.ãThese have C trucks, instead of B trucks, and are typically a lot heavierãthen their GP counter part. here is a list of their models:ã SD7 1500 HPã SD9 1750 HPã SD18 1800 HPã SD24 2400 HPã SD28,SD38 2000 HPã SD35, SDP35(*) 2500 HPã SD39 2300 HPã SD40,SDP40(*) 3000 HPã SD45,SDP45(*) 3600 HPã SD45X 4200 HPã SD50 3500/3600 HPã SD60 3800 HP (current model)ã SD70 4000 HP (newest model, in initial production)ããThen there is the later F series, which was basically like the GP andãSD, but had cowling over the engine, instead of walkways. This cowlingãis not part of the structural support, like the earlier F series.ãThese engines include: ã F40PH 3000 HP standard Amtrak engine everyone knows and loves :) ã F45, FP45(*) 3600 HPã SD40F,SD50F and SD60F which are SD40,SD50/SD60's with cowlingã  over them instead of walkways. Bought by Canadian RR's. ãã(*) Passenger versions, as indicated by extra 'P' in numberããNow to the switchers, another long list!  A switcher is typically,ãsmall, lightweight, and has a cab at one end, and no nose, instead itãusually has large windows for visibility.  EMD started out with the NCãwhich had 900 HP, and was experimental.  then followed with theãfollowing models: ãã SC,SW 600 HP ã NC, NC1, NC2, NW, NW1, NW1A 900 HP ã NW2,NW4 900 HP ã SW1 600 HP ã NW3,NW5 1000 HP ã SW8 800 HPã SW600 600 HP ã SW900 900 HP ã SW7 700 HP ã SW9,SW1200 1200 HP ã SW1000,SW1001 1000 HP ã SW1500, MP15 1500 HP ã  (MP stands for Multi Purpose, still looks like aã  switcher though, and is the current production model)ããThe original names were derived as follows, although for example theãSW900 is a 900 HP version of the original SW.ããSC - Six hundred horsepower, Cast frameãSW - Six hundred horsepower, Welded frameãNC - Nine hundred horsepower, Cast frameãNW - Nine hundred horsepower, Welded frameããThe other odd model EMD produced was the DD series, which had DD trucks.ãThese were double ended diesels, and were roughly like 2 engines putãtogether in one. They had the following:ã DD35A,DD35B 5000 HPã DDA40X 6600 HPãOnly Union Pacific had the DDA40X and the DD35A.ãBoth UP and Southern Pacific had the DD35BããGE is a bit easier to describe. They started with the U series, whichãstood for Universal. They are either B or C, based on the type of trucks.ãAll GE models use their HP in hundreds as part of the model designation,ãalong with the type of trucks and the engine series.ãThe U series had the following models:ã U18B 1800 HPã U23B,U23C 2250 HPã U25B,U25C 2500 HPã U28B,U28C 2800 HPã U30B,U30C 3000 HPã U33B,U33C 3300 HPã U36B,U36C 3600 HPããThere was also a U50 and U50C which was a double U25, with either 2 sets ofãB trucks on a span bolster (U50) or on C trucks (U50C)ãSometime in the late 70's (1977 I think) they dropped the U series, andãwent to the -7 series, all models produced there after looked like this:ã B23-7,C23-7 2300 HPã B30-7,C30-7 3000 HPã B36-7,C36-7 3600 HPã B32-8,C32-8 3200 HPã B36-8,C36-8 3600 HPã B38-8,C39-8 3900 HP (current model)ã B40-8.C40-8 4000 HP (current model)ããThey have also flipped the designation to DASH-8 40B and DASH-8 40CããThere is also a modification on the current production of engines,ãthat being a cowl (like described before) or a safety cab.ãFor EMD's the wide nose is designated by adding an M after the model nameã(like SD60M or GP60M) on GE is is a W, (Like CW40-8,DASH-8 40BW)ãThey also have the full width cowl with a W (DASH 8-40CW) bought onlyãby Canadian National and BC Rail (British Columbia Railway)ããMost of this information is in the _Second Diesel Spotters Guide_ orã_Diesel Spotters Update_ ããQ: What are the most important electric locomotives?ããSBB CFF FFS (Switzerland):ã Ce 6/8 II;  (1'C)'(C1')'; 1.65 MW;  65 km/hã Be 6/8 III; (1'C)'(C1')'; 2.575 MW; 75 km/hã  The `Crocodile', maybe the most famous electric locomotive ever. Itã  was built since 1919 for transporting heavy trains over the Gotthard.ã  This articulated locomotive was used until 1970.ã  Models of the Ce 6/8 II: Maerklin 1; Roco H0; Arnold N.ã  Models of the Be 6/8 III: Maerklin H0; Maerklin Z.ã Re 6/6 620; Bo'Bo'Bo'; 7.8 MW; 140 km/hã  This is still the most powerful locomotive (with one frame) of theã  world. It was built since 1972 for all trains on mountain lines.ã  Models: Hag H0; Lima H0; Hobbytrain N.ã Re 4/4 460; Bo'Bo'; 6.1 MW; 230 km/hã  The `Locomotive 2000' in the newest technology, designed by Pinin-ã  farina, built since 1991. Variants of the 460 will be built for theã  BLS (Switzerland) and for the VR (Finland).ã  Models: Hag H0; Maerklin H0; Roco H0.ããDB DR (Germany):ã Class 118 (E18); 1'Do1'; 3.04 MW; 150 km/hã  From 1935 to 1955 these locomotives were built for fast passengerã  trains. They were used until 1980, in Austria (OeBB 1018) until 1990.ã  Models: Maerklin H0 (DB 118), Roco H0 (DB 118, OeBB 1018).ã Class 103; Co'Co'; 7.78 MW; 200 km/hã  Since 1970, this powerful engine is used for all the fast InterCityã  trains in Germany.ã  Models: Fleischmann H0, Maerklin H0, Roco H0; Fleischmann N, Trix N;ã  Maerklin Z.ã Class 120; Bo'Bo'; 5.4 MW; 200 km/hã  The prototypes of this universal locomotive with asynchronous threeã  phase motors were built in 1979; since 1987 more 120s are in regularã  service for InterCity and freight trains.ã  Models: Fleischmann H0, Maerklin H0; Fleischmann N; Maerklin Z.ããSNCF (France):ã CC 7100; Co'Co'; 160 km/hã  In 1955 one of these locomotives established a new world record withã  331 km/h. They were used for heavy passenger and freight trains.ã  Models: Rivarossi H0; Roco N.ã BB 26000; Bo'Bo'; 200 km/hã  The SYBIC locomotive, with synchronous three phase motors, is builtã  since 1990. It is used for all sorts of trains in the whole country.ã  Model: Maerklin H0.ããSJ (Sweden):ã Rc1, Rc2, Rc3, Rc4, Rc5; Bo'Bo'; 160 km/hã  The Rc series by ABB, based on thyristor technology, was built sinceã  1967. Variants of the Rc are used in Austria (OeBB 1043), Norway (NSBã  El 16) and USA (Amtrak AEM7).ã  Models: Maerklin H0 (SJ Rc2, OeBB 1043), Roco H0 (SJ Rc5; NSB El 16)ããQ: Which high speed trains are in service today?ããHere I have collected the trains of the world that are faster than 200ãkm/h. If possible, I have included the train composition in angleãbrackets: T = locomotive; A = first class car; B = second class car;ãC = club car; D = luggage car; R = restaurant car.ããJR East/Central/West (Japan):ã Shinkansen 100; 8.88 MW; 1277 seats; 230 km/h; 1985ã  JR Central: Tokio--Osaka (Tokaido)ã  JR West: Osaka--Hakata (Sanyo)ã Shinkansen 200; 17.6 MW; 275 km/h; 1989ã  JR East: Omiya--Morioka (Tohoku), Omiya--Niigata (Joetsu)ã Shinkansen 300; 12 MW; 300 km/h; 1991ã  JR Central: Tokio--Osaka (Tokaido)ã Shinkansen 400; small profile; 240 km/h; 1992ã  JR East: Yamagata--FukushimaããSNCF (France):ã TGV PSE; 6.45 MW; 270 km/h; 200 m; 386 seatsã  Bo'Bo'+Bo'2'2'2'2'2'2'2'Bo'+Bo'Bo' <T B B B B BR A A A T>ã  In service between Paris and the south-eastern part of France (highã  speed line Paris--Lyon) since 1981. Two units can be coupled together.ã  Models: Jouef H0; Lima H0.ã TGV A; 8.8 MW; 300 km/h; 237 m; 485 seatsã  Bo'Bo'+2'2'2'2'2'2'2'2'2'2'2+Bo'Bo' <T B B B B B B R A A A T>ã  In service between Paris and the western part of France (high speedã  line Paris--leMans/Tours) since 1989. Two units can run together.ã  The TGV Atlantique holds the world record: 515.3 km/h.ã  Models: Jouef H0, Lima H0.ããDB DR (Germany):ã ICE (401/801--804); 9.6 MW; 280 km/h; 411 m; 759 seatsã  Bo'Bo'+14*(2'2')+Bo'Bo' <T B B B B B B B B B R A A A A T>ã  In service since 1991 on the three lines Hamburg/Bremen--Muenchen,ã  Hamburg--Frankfurt(M)--Muenchen, Hamburg--Frankfurt(M)--Zuerichã  (high speed lines Hannover--Wuerzburg and Mannheim--Stuttgart).ã  Models: Fleischmann H0, Maerklin H0; Fleischmann N, Trix N.ããBR (Great Britain):ã IC 225 (Class 91/Mark V); 4.7 MW; 225 km/hã  Bo'Bo'+9*(2'2') <T B B B B B R A A D>ã  In use at the east coast main line London--Edinburgh.ããRENFE AVE (Spain):ã TAV; 8.8 MW; 250 km/h; 200 m; 329 seatsã  Bo'Bo'+2'2'2'2'2'2'2'2'2+Bo'Bo' <T B B B B R C A A T>ã  These trains are very similar to the TGV. Since 1992 they run on theã  new line (normal gauge) between Madrid and Sevilla.ããFS (Italy):ã ETR 450; 250 km/h (Pendolino); 1st class onlyã  From Roma to Torino, Venezia, Genova, Napoli and BariããQ. How does a diesel locomotive work?ããA. Actually, this is a trick question.  Locomotives come inãdiesel-electric, diesel-hydraulic, and as a test a steam-electricãengine was built.  The first part of the name indicates how the powerãis generated and the second how it is transmitted to the drivingãwheels.ããThe diesel engines are huge internal combustion engines (sometimesãmore than one per locomotive), named after Rudolf Diesel who patentedãthe concept in 1892.  In a diesel-electric they are used to powerãelectric generators, and the electricity is used to drive electricãmotors.  These are called traction motors and one is attached by aãgear system to each powered axle.ããI don't know the details of how diesel-hydraulic engines work, butãbasically something like an automatic transmission is used to connectãthe diesel motors to the axles via driveshafts (I'm making this allãup, so feel free to correct me!)  It turns out to be very difficult toãbuild these to handle the large loads involved, so all modernãlocomotives [in the United States - see below] are of theãdiesel-electric variety.ããUntil 1980, there were still modern diesel-hydraulic locomotives builtãby the Deutsche Bundesbahn in West Germany (three major series: theãgood old two- motored 220/221 (V200), the light 211/212 with one motorãand the cab in the middle and the 215/216/217/218/219 with oneãmotor/two cabs for mixed service).  Today there are no dieselãlocomotives built in Germany, because there are so many Russian orãBulgarian diesel-electric engines from the Deutsche Reichsbahn (EastãGermany). New diesel locomotives will be built in the diesel electricãtechnology with 3-phased AC transmission.ããFinally we have the steam-electric.  I don't have the references inãfront of me, but I believe the New York Central experimented with anãengine which looked like an F3 but which had a coal-powered steamãboiler which as used to run a generator, with the rest of the systemãas in a diesel-electric.  This is even more speculative than theãdiesel-hydraulic description, so don't bet any money on it.ããQ. What are "dynamic" brakesããA. As described in the previous question, diesel-electric locomotivesãhave motors attached to each axle.  Normally power is supplied to theãmotors causing the wheels to pull the train.  However, due to theãmagic of electromagnetics, if the wheels are turned by an externalãforce (such as gravity pulling a train down a hill) the motors willãrun as dynamos, generating electricity.  Since energy is conserved,ãthis electric power has to come from somewhere, which in this case isãthe kinetic energy of the engine.  In simple English, running theãmotors as dynamos will put a drag on the engine, which can be helpfulãwhen running a very heavy train down a long grade.ããThe amount of electric power generated is substantial, and it has toãbe used up somehow to cause a drag on the wheels.  This is done byãusing a bank of resistors which convert the electricity to heat whichãis then radiated away.  On EMD locos these resistors appear as aãbulging grille near the center of the roof. Alco, GE, FM, and BLWãlocos with dynamics have extra grills somewhere on the loco, but noãbulges like the EMD "blister".  On older Alcos (like RS3's) and on theãBaldwin DRS/AS types, these grills were in the short hoods.ããModel shells are often offered with these external indications ofãdynamic brakes, although they of course have no function.  A givenãprototype locomotive is usually available both with and withoutãdynamic brakes.ããQ. How do steam locomotives work?ããA. Another trick question!  I'm not really familiar with all of theãdetails, so I'm really writing this in the hopes of getting netters toãprovide more authoratative answers.ããSteam engines came in three basic varieties: reciprocating pistons,ãgeared drives, and experimental turbines.  All work by boiling waterãto make pressurized steam, and the energy in this steam is used toãmove the engine.  The earliest engines burned wood for fuel. Mostãsteam engines used coal, and towards the end of the steam era oil wasãused, primarily to get around air pollution regulations.ããIn a reciprocating piston design the pressurized steam is sent intoãexpansion cylinders, which were usually mounted on the outside frontãend of the frame.  The steam expands to push a piston back, and theãpiston is connected via a crosshead to the main driving rods.  Theseãrods convert the linear motion of the piston to the circular motion ofãthe driving wheels.  There are many variations on this design, such asãusing multiple cylinders to increase the amount of energy extractedãfrom the steam but they all fall into the category of improvements toãthe basic design.  Note that once the steam has been used it isãexhausted to the atmosphere, which is why the tender on a steamãlocomotive is mostly water and a relatively minor amount of fuel.ãNote that this design with lots of exposed moving parts is alsoãsignificantly sexier than a diesel electric...ããI have no idea how geared locomotives work - perhaps some loggingãexpert will write a few paragraphs on the issue?ããAs a PRR fan I will attempt to describe their turbine engines - otherãexperiments may have differed in the details.  As before steam isãproduced, but rather than using pistons is was fed through a rotatingãturbine which was directly geared to the driving wheels.  Apparentlyãthe design did a fairly good job of producing power efficiently, butãthe steam had minute particles of coal ash in it which rapidlyãdestroyed the finely balanced turbine blades, making it impractical toãmaintain.  GE also produced such an engine, with the same problems.ããQ. What is a "gas-turbine" locomotive?ããA. General Electric produced several species of gas-turbines, as didãBaldwin.  These locos were basically the same as a diesel-electric,ãexcept that the prime mover was a gas turbine.  The only successfulãproduction models came from GE, all of which were sold to the UnionãPacific.  These came in essentially two types:ãã - The first version was a 4,500 h.p. model introduced in 1949.ã   The prime mover was a GE gas-turbine which turned aã   generator to provide current to eight traction motors.ã   Wheel arrangement was B-B + B-B, the same as the later U50.ãã - The second model went into production in 1958.  ã   It consisted of two car bodies, a lead control unit and aã   second unit containing a 10,500 h.p. GE gas-turbine.  Eachã   car body had two C trucks. At first, the two generatorsã   attached to the turbine were rated together at 8,500 h.p.,ã   later uprated to 10,000 h.p. ããThirty large turbines were produced by GE.  Compared to firstãgeneration diesels, these machines were reliable. They consumed hugeãamounts of "Bunker C," a thick black oil which was considered waste atãthe time and was initially very cheap.  Heated tenders [to keep theãfuel from solidifying] were provided for each locomotive, custom madeãfrom old steam tenders.  Bunker C became more expensive when it becameãan ingredient for making plastics.  Increased fuel expense doomed theãgas-turbine, which could not operate with the fuel efficiency of theãdiesel. [No way was ever found to cool the turbine blades like aãpiston engine cooling system so the turbine had to operate at a lowerãless efficient temperature than a diesel.] ããGas-turbines were in revenue service roughly from 1950 to 1969.  Noneãof the first generation turbines remain.  At least one of the secondãgeneration turbines is on display (in Ogden, Utah).ããGas-turbines have also been used in Europe. The SNCF (French NationalãRailway Society) introduced its Turbotrains ETG (Element a Turbine aãGaz) and RTG (Rame a Turbine a Gaz), very noisy passenger units ofãfour to five wagons, in the sixties. They can reach 180 km/h and areãstill in use as fast trains on the non-electrificated lines today. Aãvariant of the RTG is in use in Canada. The other European companiesãhave stopped their tests with gas turbine traction, because gasãturbines consume large amounts of fuel and produce a very loud highãfrequency noise.ããQ: How do electric locomotives work?ããElectric locomotives receive power from the overhead cable with aãpantograph.  The current system can be (1) a DC system (650 to 3000 V)ãor (2) an AC system (15000 or 25000 V).ããTraditional electric engines work in one of two fashions: either theãmotors are directly supplied with full voltage or the current isãtransformed to lower voltage by a transformer in the locomotive, thenãit may be directly transmitted to the motors or rectified if DC motorsãare used.ããThe earliest electric locomotives had one or two large motors in theãmiddle of the frame, which drove the wheels mechanically, similarly toãthe transmission of steam engines.  Since 1940 or so, each axle hasãits own motor; usually a modern locomotive has two or three bogiesãwith two or three axles each.ããThe newest engines have a DC circuit which is either fed by the DCãfrom the overhead cable or by the transformed and rectified AC.  Theãelectricity from this circuit is then converted electronically intoãthree phase current of variable frequency and voltage, by which theãmotors, which can be built very simple, are fed.  This new technologyãallows the engines to feed the electrical energy back into theãoverhead cable while braking.ããMost of the fast trains of the world have electric traction.  It isãexpensive to build transformers and overhead cables above the railwayãlines, but the engines are much more powerful and less heavy thanãDiesel engines because they don't have to carry their fuel around. Forãexample, a modern four axle engine (80 t) can easily have a power ofãmore than 6 MW.  The electric engines don't need a mechanicalãtransmission because the motors can develop high power at all speeds.ãThis is particularly true for the new three-phase current technology.ãElectric locomotives are "clean": they don't pollute the localãenvironment, although the power plants may depending on how theyãgenerate the electricity.ããIf DC is used in the overhead wires, the cables must be very heavy toãtransmit large amounts of energy.  Many transformer stations areãneeded along the railway.  That 's why all the high speed trains useãAC voltage today.ããThere is a wide variety of current systems:ã1. AC 25000 V, 50 Hz: Portugal, north France, Great Britain,ã   Denmark, Finland, Italy (in the future), south-east Europe,ã   CISã2. AC 15000 V, 16.66 Hz: Norway, Sweden, Germany, Switzerland,ã   Austriaã3. AC 11000 V, 25 or 60 Hz: USA (Amtrak north-east Corridor)ã4. DC 3000 V: Spain, Belgium, Italy, Poland, CISã5. DC 1500 V: south France, Netherlandsã6. DC 650/750/1200 V, third rail: south England, urban railwaysããThe european railway companies have several types of locomotives thatãare compatible to two or more of these systems.  For example inãFrance, all the TGVs (Train a Grande Vitessse = high speed train) haveãtwo or three systems.  There are plans to reduce the number ofãelectric systems in Europe, but this seems to become very expensive.ãããã