Electric locomotive

Electric locomotives (short electric locomotives or electric locomotives, Abbreviation: Electric Locomotive ) are self-propelled tractors by rail. The drive is with them purely electrically, in contrast for example to diesel-electric, diesel-hydraulic or electric steam locomotives.

• 3.1 DC
• 3.2 Three-phase
• 3.3 AC
• 3.4 Application of traction power systems

• 4.1 DC
• 4.2 Three-phase
• 4.3 AC
• 4.4 Umrichterfahrzeuge (all current types )

General Overview

Electric locomotives are disposed of over the railway overhead wires or supplied through busbars with rare energy that is transferred from the side of the drive mounted on the roof or power rails pantographs on the vehicle. A usually arranged on the roof of the main switch can completely separate the locomotive from the power supply. This electric locomotives have the advantage that they themselves have no exhaust emissions ( but at a theoretical power over coal power plants have a higher output than other locomotives) can only be used there, but where a power supply is available. Furthermore, it is an advantage that electric motors already put at start-up to full torque, as opposed to diesel locomotives, where the torque when starting slowly builds up. This can accelerate faster electric locomotives or train a slightly heavier pull than diesel and steam locomotives. Because of course the way the electricity does not affect the electric locomotives, electric locomotives to have first used in countries and regions where the use of electricity by example Hydropower plants is far cheaper than using coal or diesel. The Switzerland, Austria and Sweden are the countries in which this requirement applies.

Some types of electric trains are powered by electric power cars that run at the front and / or back of the train and never be disconnected during normal operation of the car. This is technically largely to electric locomotives. The only difference is in the equipment with only one cab and the clutch and transitional devices to the multiple-unit intermediate cars. Examples of modern electric trains with power heads are the first two generations of the ICE (ICE 1 and ICE 2 ), the Spanish unit trains of series 102 and 130, the first series of the S-Bahn Zurich and the French TGV trains. The latter, however, also the first bogie of the current directly behind the engine head means the car is also driven in some series (TGV Sud -Est, Euro Star ).

Examples of modern Elektrolokomotivenbau are Bombardier TRAXX, Siemens and Alstom Prima Euro Sprinter.

Construction

The locomotive is usually carried by the drive of a box with the cabs and the engine room.

Box and engine room

The box consists of a rigid main frame with welded side walls and detachable roofs. At the ends of the leaders rooms are housed, between which there is a large machine room is located where the electrical switching, control and transmission equipment are set up protected from the weather. Thus, the operator can not touch dangerous voltage, the device either behind bars or on newer locomotives are housed in closed cabinets. The most dangerous high voltage range is also shut off. Access is only possible with a key that is only released when the pantograph is lowered and the electrical equipment is grounded.

The devices are arranged along corridors. It can be either a transition be centrally located in the engine room or two gears along the walls. A mixture of the two systems is also possible. In corridors along the side walls usually belongs to a closed-off in addition to the above described high voltage range.

In the engine room of modern locomotives with no moving parts are visible.

Drive and drive

The main frame, in turn, rests generally on the frame movable bogies, which are in turn supported by two or three wheelsets. Modern Electric locomotives are performed either with Einzelachsantrieb or for reasons of cost with group drive ( two motors connected in parallel).

The driven wheels or axles of the first locomotives were coupled structurally the simplest way possible with the engine, which inevitably led to the first Einzelachsantrieb; sometimes only one axis of the traction unit was driven anyway. Very early also joined - for example in the locomotive " Le Drac " the Chemin de Fer de La Mure - a drive of several axles with independent motors.

At increasingly higher power, however, the summary of the drive was preferred in as few engines because it specifically lighter and cheaper equipment could be obtained. First major electric locomotives thus had great on the main frame low-speed engines, and landing gear consisted of several coupled with the driving axles rods that were driven either by oblique cranks or jackshafts. Similar to steam locomotives there were also additional run- axes to support overhanging frame parts. In addition, engines were in pairs coupled together mechanically in the locomotive body.

But soon it turned out that at higher speeds and when linking multiple motors resonant vibrations of the gearbox and the entire Lokomotiv structure occurred, which caused considerable damage. Therefore, soon made ​​efforts to develop a Einzelachsantrieb, which was suited to the needs at higher speeds. In addition to the "Siemens -Schuckert - drive " with vertical engines of the Swiss Jakob Buchli 1918 developed at the Brown, Boveri & Cie the Buchli drive.

The traction motor is in the locomotive for speeds up to 140 / 160 km / h in part from the axis, partially supported by the bogie frame ( nose-suspended drive ). This construction enables a simple driving, since the engine relative to the axis does not move. The disadvantage is the large mass of the engine, which is directly unabgefedert on the wheels. This causes when driving the joints of the rails are not checked, thereby acting relatively large forces on the rails. For higher speeds, the traction motors will be completely suspended from the bogie frame or the locomotive body, so that the joints without too much pain on the track. The drive must be relative movement between its spring suspension and of the axis offset, so that in general a hollow-shaft drive is employed.

Equipment

In the following the main facilities are listed by electric locomotives. It is important to distinguish between parts that are found only in AC locomotives or only in DC locomotives and those that occur in all electric locomotives. Multi-system vehicles are suitable for DC and AC operation and must therefore all the facilities listed below have.

Significant components of electric locomotives for AC operation are:

• The main transformer with main switch
• The driving stage controller or instead the traction inverter

Significant components of electric locomotives for DC operation are:

• Fast switch ( sometimes referred to as main switch)
• Step switch for starting resistors or instead traction converters

Significant components of all electric locomotives are independent of the current:

• Pantograph
• Traction motors and associated cooling fan,
• Cabs
• Braking resistors with cooling fan (often no longer needed with modern locomotives with regenerative brake)
• Buffer and coupling with which the tensile force is transmitted to the train
• Air compressor for the air brake system ( rarely vacuum pump for vacuum brake )
• Sanding gear
• Flange lubrication
• Train control (among Sifa, PZB, LZB )

Energy supply

→ Main article: rail power

The first trains with electric traction were operated with DC or three-phase, which allowed the construction of vehicles with simple traction motors and simple controls. Only later did the art for the use of single-phase AC was available, which simplified the contact line and the power supply.

Direct current

The electrification with direct current was the easiest to accomplish. The traction motor had a simple structure and its performance could be regulated with a series resistor. The energy transfer is more difficult over long distances, so that many feed points are needed. On the other hand the vehicle can be easily assembled, because no transformer is needed on the vehicle. The system is still used today. The electrification with 3000 V DC voltage is excessively stretch the world's most widely used system (as of 1980). For new large projects in the long-distance transport but it is no longer used. Problems are the major streams that need to be transferred, for example, for high-speed operation of the contact line and cause great losses.

A special form of DC-powered locomotives provide battery locomotives dar. The advantage is, as in the battery railcars used for passenger transport is to be dependent on any external infrastructure for power supply. However, the application range is limited to areas with less power due to the limited battery capacity. Battery locomotives come since the 1930s in the London Underground as an operating vehicle for service work in tunnel sections are used, in which the busbar is turned off for maintenance. There are also isolated areas of application in mining, industrial railway traffic and historically as the experimental locomotive FS E.421.

Three-phase

Three-phase current was first applied in the experimental farm on the route Marie Felde - Zossen. The asynchronous traction motors of the locomotive was powered directly from a three-pole overhead line, the cruise control was carried out by varying the frequency of the supply voltage at the power plant.

For practical operation, a two-pole overhead line continued through to the track as the third conductor. Compared to the DC operation, the energy could better be transmitted over longer distances, and it could be a reliable regenerative braking realize why the system is still used today in some Swiss mountain railways easy. By 1976, large parts of the Ferrovie dello Stato were electrified with AC in northern Italy.

Alternating current

AC can be transmitted with low loss over long distances due to high voltage. On the other hand, was the beginning of the electrification of the construction of traction motors for single phase alternating extremely complex and succeeded only with small power frequencies. In 1905 Test runs have been performed with single-phase AC, but sat down as the system most suitable power supply for remote paths later by. The high AC voltage is stepped down on the traction units with transformers to operate the motors and switching devices to lower values ​​.

With the advances in power electronics and later the widespread frequency of 50 Hz was used. It was in the same direction at the beginning of the 50 -Hz alternating current with diodes, and then used as a supply of a so-called mixing phase motors. For new electrification today usually the system with 25 kV, 50 Hz is applied, which is now the world to meet the second most.

Application of traction power systems

→ Main article: List of traction power systems

From this historical development shows that today, depending on the date of the establishment of the first plants different traction power systems are used. In Europe, the various systems hinder cross -border traffic which can only be overcome with multi-system vehicles.

The main railway power systems in the world ( ranked according to voltage level ):

For tram, light rail, metro and suburban rail networks DC voltages between 500 and 1500V are, if they are operated independently of mainline networks, mostly used. The contact wire voltage in tram networks rarely exceeds this 1000V.

The driving and power control

Direct current

For DC powered locomotives of the series-wound traction motors are connected upstream of the start-up resistors are shorted gradually with a derailleur. As long as the resistors are switched on, some of the energy in the locomotive is converted into heat, so that an economic operation is achieved only when completely short-circuited rolling resistance. Later chopper controls were used instead of the resistors, which allow a nearly lossless power control.

More speed steps arising from the use of field weakening. It is partially short-circuited, the field winding, so that the driving motor can achieve higher speeds with decreasing torque. For vehicles with multiple engines at low speeds they are connected in series, in parallel to achieve higher speeds. It is created by the various circuit configurations at four resp. six traction motors a much larger number of lossless speed steps.

Three-phase

For locomotives that relate phase current from the contact line, asynchronous traction motors were used with slipring usually. The power control was carried out by switching additional resistors in the rotor circuit, which were briefly closed in stages on the journey, as well as by changing the number of poles of the motors using the Dahlander. Thus, it was only two or four economic speeds possible.

Alternating current

In electric locomotives with AC operation, the voltage of the traction motors is controlled by a so-called rear derailleur. This consists of a step switch, or moving switches, are controlled directly or through intermediaries, in Sagittarius with the individual taps of the transformer coils by hand. Depending on the design, the switching device is arranged either on the high voltage side or on the low voltage side of the transformer. When placed on the high voltage side of the switching device is smaller because the streams are smaller, the demands on the insulation material, however, are much higher.

Today's electric locomotives use modern energy efficient power electronics, they just do not have a transformer with a few solid taps on which the traction inverter (usually one per bogie ) and the auxiliary converter ( HBU ) are connected. This forms the supplied DC or single phase AC current into three-phase alternating current with variable frequency, which supplies the commutator and low-maintenance AC drive motors. Multi-system locomotives can go with different catenary voltage. Thus, a cross-border traffic is possible - without time-consuming change of locomotive.

Umrichterfahrzeuge (all current types )

Today's electric locomotives use modern energy efficient power electronics. Regardless of the type of current used, the supplied energy is converted to the vehicle in three-phase alternating current and fed asynchronous traction motors, which are almost maintenance-free.

For AC vehicles in front of the converter, a transformer with a fixed gear ratio is still arranged, which sets the voltage to a lower value and making the adjustment to the rated voltage of the AC systems.

The auxiliary equipment ( fans, pumps, air compressors, etc.) are usually fed via a separate smaller converter ( auxiliary converters ) with three-phase alternating current. This converter is directly connected to the catenary voltage in direct current locomotives with AC locomotives the power supply is usually its own transformer winding. The output frequency of the auxiliary system power converter is controlled depending on the power requirements of the connected loads. For older locomotives, the auxiliary supply voltage is generated by a rotary transformer.

Thus, the locomotive remains are seldom as possible, important systems are duplicated or designed such that failure of one system can continue to run at reduced power. The traction power converters are often designed so that the failure of a semiconductor, the engine can still be operated with at least a portion of the engines.

Multi-system locomotives can go with different catenary voltage. This is possible without time-consuming change of locomotive a cross-border traffic.

History

→ Main article: History of the electric drive of rail vehicles

• An early experimental electric railway train is Thomas Davenport, a blacksmith from Vermont, United States attributed. He led in 1835 before a small, by an electric motor powered model of a rail track.
• From the Scotsman Robert Davidson in Aberdeen is reported that he in 1838 built an electric locomotive that attained a speed of four miles per hour.
• The U.S. Patent Office employees Charles Grafton Page (1812-1868) began in 1850 to build an electric locomotive. Their 15 kW " piston " engine consisted of two coils with recessed therein rod anchors. These were moved by alternately switching the coils as in a reciprocating steam engine back and forth. This piston movement is transferred to a crank shaft to the drive wheels of a three-axle truck.
• In Fischbach (Nassau ) A.D. Lahn was 1840 Johann Philipp Wagner drive a small driven by an electric motor with trailer on a rail circle of 20 meters in circumference. He was then commissioned to build a functioning large " electromagnetically driven " locomotive and a sum of 100,000 florins was put to him for disposal. However, he failed in the implementation, allegedly due to lack of knowledge about the connection between battery capacity and driving power.
• The company of Werner Siemens built in 1879 for the Berlin Trade Fair biaxial electric locomotive on the on a 300 -meter circuit could pull three cars, each with six people. It is considered the first practical electric locomotive.
• In most early commercially operated electric railways tram -like railcars were first used, for example, in 1881 built at the Siemens & Halske first electric tram to Hauptkadettenanstalt in Great light field at Berlin, in 1895 put into operation the first German electric mainline Meckenbeuren - Tettnang in the former Kingdom of Württemberg and other tracks.
• From 1890 electric locomotives were used to a remarkable extent, on the metro routes from London. Especially the limited space of the tunnel profile here forced to turn away from the railcars and biasing the drive in a separate vehicle at the top of the train. The City and South London Railway sat here the first electric trains with a locomotive covering. By 1935 the London subways rode locomotives.
• 1895 took the first electric locomotive in the control track on the operation. Built by General Electric locomotive was used by the Baltimore and Ohio Railroad to carry passenger trains through the tunnel city of Baltimore. On this route could be used because of the smoke nuisance no steam locomotives.
• 1901-1903 were carried out by the Research Association for Electrical rapid transit on the military railway Marie Felde - Zossen Jiiterbog Quick driving tests. The rotational power needed is supplied to the vehicle via a three-phase overhead contact line. The power control was not in the drive vehicles, but in the power plant. A railcar AEG reached a speed of 210.2 km / h
• 1902 opening of the three-phase operation by Rete Adriatica on the Valtelina in northern Italy. This is the first electrically operated main track in the world. The locomotives were from full in Budapest.
• In 1903 the iron ore railway Chemin de Fer de La Mure on electrical equipment. The DC of the locomotive with the wheel arrangement modern Bo ' Bo ' via a double-pole overhead line with 1200 V and -1200 V is supplied. The web is only in 1950 switched to normal simple contact lines at 2400 V.
• 1904 electrical test operating on the route Seebach Wettingen in Switzerland. Here for the first time, the voltage of 15 kV was used 16 ⅔ Hz, the current standard in Germany, Austria, Switzerland, Sweden and Norway. 1909 The trial operation was unnecessary because then the electrified from the start Spiez -Lenk BLS was completed. At the beginning of 50 Hz in these experiments were run on a factory siding also experiments with 15 kV. Here, a rotary transformer is used to convert the high -voltage and to regulate the power to the locomotive. The frequency was reduced to 16 ⅔ Hz, because at 50Hz problems occurred in the telephone network.
• 1904 was the narrow-gauge railway from Innsbruck to Fulpmes Stubaital as the first single-phase AC railway in the world in full operation ( 3000 V, 50 Hz).
• 1905 takes the Ammergaubahn the first single-phase AC motor coaches (LAG 674-677 ) and a few weeks later, the first locomotive (LAG 1, later DR series E 69 ) in operation. The current system is 5.5 kV 16 ⅔ Hz Switching to the usual voltage of 15 kV will only be 1950.
• 1906, the three-phase operation was recorded on the route through the Simplon tunnel.
• 1911 Opening of the operation on the route Dessau- Bitterfeld. First electric gauge railway in Germany, initially with 10 kV 15 Hz
• 1912, consisting of the Karwendel and Außerfernbahn Mittenwaldbahn of Innsbruck was taken to Reutte first Austrian mainline railway with 15,000 V and 16 ⅔ Hz AC operation.
• 1913 electrical operation on the Lötschberg Railway in Switzerland.
• 1920 electrical operation on the Gotthard railway. The electrification of this route was forced on so that Switzerland during times of crisis less of carbon imports from neighboring countries became dependent.