A railway electrical system supplies power to trains and trams without a major on-board driver or local fuel supply. Electric trains use electric locomotives to transport passengers or goods in separate cars or dual electric units, passenger cars with their own motors. Electricity is usually generated at large and relatively efficient generating stations, transmitted to rail networks and distributed to trains. Some electric trains have their own generating stations and transmission lines but most buy electricity from electric utilities. Trains usually provide their own distribution lines, switches and transformers.
Power is supplied to moving trains with continuous conductors running along the path which usually take one of two forms: the air duct, suspended from a pole or tower along the track or from the structure or ceiling of the tunnel; the third rail is installed at the track level and contacted by the "pickup shoe" shear. Both overhead wires and third rail systems typically use a rail that runs as a return conductor but some systems use a separate fourth rail for this purpose.
Compared to the main alternatives, diesel engines, electric trains offer much better energy efficiency, lower emissions and lower operating costs. Electric locomotives are also usually quieter, stronger, and more responsive and reliable than diesel engines. They have no local emissions, important advantages in tunnels and urban areas. Some electric traction systems provide regenerative braking that converts the kinetic energy of the train back into electricity and returns it to the supply system for use by other trains or public utility networks. While diesel locomotives burn petroleum, electricity can be generated from a variety of sources including renewable energy.
Disadvantages of electrical attractiveness include high capital costs that may be uneconomical on lightly traded routes; lack of relative flexibility - because electric trains require an electric path (or overhead cable) - and susceptibility to power failures. Different regions can use different voltages and supply frequencies, which are complicated through the service and require greater locomotive strength complexity. The limited free distances available under the air ducts may block the efficient service of double-stack containers.
The railway power has steadily increased in recent decades, and by 2012, electric trajectories account for nearly a third of the total track globally.
Video Railway electrification system
Classification
Electrification systems are classified by three main parameters:
- Voltage
- Now
- Direct current (DC)
- Alternating current (AC)
- Frequency
- Contacts system
- Third rail
- Fourth rails
- Overhead lines (catenary)
- Overhead lines plus linear motors
- Four rail system
- Five rail system
Electrification system selection is based on the economy of energy supply, maintenance, and capital cost compared to revenue earned for goods and passenger traffic. Different systems are used for urban and intercity areas; some electric locomotives may switch to different supply voltages to allow for flexibility in operation.
Standard voltage
Six of the most commonly used voltages have been selected for European and international standardization. This is independent of the contact system used, so, for example, 750Ã, VÃ, DC can be used with a third rail or air duct.
There are many other voltage systems used for railroad electrical systems around the world, and the list of railroad electrical systems includes standard voltages and non-standard voltage systems.
The allowable voltage range allowed for standard voltages is as stated in BS, ENÃ, 50163 and IEC 60850 standards. It takes into account the number of current train drawings and their distance from the substation.
Maps Railway electrification system
Direct current
Trains should operate at variable speeds. Until the mid-1950s this was only practical with a brush type DC motor, although the DC can be supplied from AC catenary through on-board power conversion. Because the conversion did not develop well in the late 19th and early 20th centuries, the earliest electrification trains used DC and many still did, especially the fast transit (subway) and tram. Speed ​​is controlled by connecting the traction motors in various parallel-series combinations, by varying the traction motor field, and by inserting and removing the initial resistance to limit the motor current.
Motors have very little space for electrical insulation so generally have low voltage ratings. Since the transformer (prior to the development of power electronics) can not lower the DC voltage, the rail is equipped with a relatively low DC voltage that the motor can use directly. The most common DC voltage is listed in the previous section. The third (and fourth) rail systems almost always use voltages below 1kV for safety reasons while overhead cables typically use higher voltages for efficiency. (Relative "low" voltage, even 600 V can be instantly shut off if touched.)
Because utilities supply high-voltage AC, DC trains use converter stations to produce relatively low DC voltages (typically 3000 volts or less). Initially they used a rotary converter, some of which were still operating, but most were replaced first by rectifiers of mercury arc and then by semiconductor rectifiers.
Since the electrical power is equal to the current voltage time, the relatively low voltage in the existing DC system implies a relatively high current. If the DC power on the contact wire will be supplied directly to the DC traction motor, minimizing resistive resistance requires short short supply/short supply wires and near-term converter stations.
The distance between feeder stations on the third 750 V train system is about 2.5 km (1.6 mi). The distance between the feed stations at 3 kV is about 7.5 km (4.7 miles).
Due to this problem, modern high-speed rail projects generally use high-voltage AC once the technology is available. However, there is interest among train operators to re-use DC at higher voltages than previously used. At the same voltage, DCs often have less losses than AC, and for this reason a high voltage current is already used on some mass transmission lines. DC avoids electromagnetic radiation attached to the AC, and on these railroads also reduces interference with signals and communications and reduces the risk of hypothetical EMF. DC also avoids the problem of AC power factor. Of particular interest to railroading is that the DC can provide constant power with one non-spiral cable. Constant electricity with AC requires a three-phase transmission with at least two unscreened cables. Another important consideration is that AC three-phase electrical frequencies should be carefully planned to avoid unbalanced phase loads. Part of the system is supplied from different phases assuming that the total load of the three phases will come out. At phase-break points between areas supplied from different phases, a long supply lag is required to avoid short-circuit with rolling stock using more than one pantograph at a time. Some railroads have tried three phases but substantial complexity has made standard practice one phase despite the occurrence of interruption in the flow of power that occurs twice each cycle. An experimental DC 6kV train was built in the Soviet Union.
The increasing availability of high voltage semiconductors enables the use of higher and more efficient DC voltages that until now have been only practical with air conditioning.
Some DC locomotives use a set of motor generators as a "stepdown transformer" to produce more convenient voltage for additional loads such as lighting, fans and compressors but they are inefficient, noisy and unreliable. The solid-state converter has replaced it. The state-of-the-art locomotives have even replaced traditional universal-traction motors with a three-phase AC induction motor driven by a special purpose AC inverter, a variable frequency drive.
System Overhead
1.500Ã,V DC is used in Japan, Indonesia, Hong Kong (part), Republic of Ireland, Australia (part), France (also uses 25 k kV 50 Hz AC), New Zealand (Wellington), Singapore (on MRT North East Line ), The United States (Chicago area in the Metra Electric district and the interurban line of the South Shore Line and in Seattle, Washington - Transit Sound Sound rail line). In Slovakia, there are two narrow gauges in the High Tatras (one of the tooth braking). In the Netherlands used on the main system, along with 25 kV on HSL-Zuid and Betuwelijn, and 3000 V south of Maastricht. In Portugal, it is used on the Cascais Line and in Denmark on a suburban S-train system (1650 V DC).
In the United Kingdom, 1,500 VÃ, DC was used in 1954 for Woodhead trans-Pennine route (now closed); the system uses regenerative braking, enabling energy transfer between ascent and descending train on a steep approach to the tunnel. The system is also used for suburban electrification in East London and Manchester, now converted to 25 kV AC. Now only used for Tyne and Wear Metro. In India, 1,500 V DC was the first electrification system launched in 1925 in the Mumbai area. Between 2012-2016, electrification is converted to 25 k kV 50 Hz AC which is a national system.
3 kV DC is used in Belgium, Italy, Spain, Poland, northern Czech Republic, Slovakia, Slovenia, South Africa, Chile, former Soviet Union countries (also uses 25 kV 50 Hz AC) and the Netherlands (from the south of the city) from Maastricht to the Belgian border, which is currently exclusively used by the Belgian NMBS railway company). It was formerly used by Milwaukee Road from Harlowton, Montana to Seattle-Tacoma, opposite the Continental Divide and included branches and extensive loop lines in Montana, and by Delaware, Lackawanna & Western Railroad (now New Jersey Transit, converted to 25Ã,kVÃ, AC) in the United States, and the Kolkata subway (Bardhaman Main Line) railway in India, before being converted to 25Ã,VA 50Ã,Â,00 AC.
DC voltages between 600 V and 800 V are used by most tram networks (trams), electric bus networks and underground systems (subway).
Sidney Howe Short designed and produced the first electric motor that operates a gearless tram. The motor has an armature that is connected directly to the hopper shaft for its driving force. Short pioneer "use of hidden feed channel system" thus eliminating the necessity of overhead wires, trolley poles and trolleys for street and train cars. While at the University of Denver, he undertook an important experiment that determined that some powerful car units were a better way to operate trains and trolleys.
Overhead system with linear motor
View overhead system with linear motor
Third rail
Most electrification systems use cables overhead, but the third train is a choice of up to 1,500 V, as is the Metro Line 3. The third rail system exclusively uses DC distribution. The use of air conditioning is not feasible because the third rail dimension is physically very large compared to the skin depth that the alternating current passes through 0.3 millimeters or 0.012 inches in the steel rail. This effect makes the resistance per unit length to be very high compared to the use of DC. The third rail is more compact than the overhead cable and can be used in smaller diameter tunnels, an important factor for the subway system.
The third rail system can be designed to use up contact, side contact, or bottom contact. The upper contacts are less secure, because the live rails are exposed on people who tread the rails unless the insulation hood is available. The third side and the third contact rail can easily have a shield inserted, carried by the rail itself. The third rail of the unknown top contact is susceptible to disturbances caused by ice, snow and falling leaves.
The DC system (especially the third rail system) prevents the use of low-level platforms and is limited to relatively low voltages. The latter can limit the size and speed of trains, and limit the power available for passenger comfort, such as air conditioning. The low voltage also means that the long distance transmission is inefficient and thus the transformer is often required along the line. This may be a factor that supports overhead cables and high voltage AC, even for urban use. In practice, the top speed of a train on a third rail system is limited to 100 mph (160 km/h) because above that speed reliable contact between the shoe and the rail can not be maintained.
Some streetcar (tram) use the current rail channel. The third rail is below the road surface. Tram take the current through the plow (US "plow") accessed through a narrow gap in the street. In the United States, many (though not all) tramway systems in Washington, D.C. (discontinued in 1962) operated in this way to avoid unsightly wires and poles associated with electric traction. The same is true with the former Manhattan tram system. The proof of this mode of walking can still be seen on the track down the slopes on the north access to the abandoned Kingsway Tramway Subway in central London, England, where the slot between the rails that runs is clearly visible, and on P and Q The roads west of Wisconsin Avenue in Georgetown neighborhood in Washington DC, where the trail left behind has not been paved. Slots can be easily confused with slots that look similar to tram/cable cars (in some cases, slot channels are originally cabling slots). Losses from the channel collection include much higher initial installation costs, higher maintenance costs, and problems with leaves and snow entering into slots. For this reason, in Washington, DC cars on several lanes are converted to the upper wire on leaving the city center, a worker in the "plow hole" takes off the plow while another lifts the trolley pole (until now connected to the roof) to the wire overhead. In New York City for the same reason the cost and efficiency of operation beyond the wire over Manhattan is used. Similar replacement systems from channel to upper wire are also used on the London tram line, especially on the south side; a typical turning point is at Norwood, where the channel is curling sideways from amongst the ongoing rails, to provide a garden for shoes or plows that are detached.
A new approach to avoid overhead wires was taken by the "second generation" tram/tram system in Bordeaux, France (entered into service from the first line in December 2003; the original system was discontinued in 1958) with APS (alimentation par sol-ground) feed currently). This involves a flat third rail with a surface like the top of a running rail. Circuits are divided into segments with each segment being energized in turn by the sensor of the car as it travels through, the remaining remaining rails "dead". Since every energy segment is completely covered by a long articulated car, and dies before being "revealed" by the vehicle journey, there is no danger to pedestrians. This system has also been adopted in some parts of the new tram system in Reims, France (opened 2011) and Angers, France (also opened 2011). Proposals are available for a number of other new services including Dubai, UAE; Barcelona, ​​â € <â €
The London Underground in the UK is one of the few networks that use the four rail system. The additional rail carries an electric current which, on the third rail and overhead network, is provided by the running rail. On the London Underground, the top three contact rails are next to the trajectory, energized at 420Ã, V, DC and the fourth rail with the top contact is centrally located between the walking rails in -210Ã,V DC, which combine to provide traction voltage 630Ã, V DC. The same system is used for Milan's earliest underground line, Metro 1 line 1, which is more recent lineup using top catenary or third rail.
The main advantage of the four-rail system is that no trains carry any current. This scheme was introduced because of a backflow problem, intended to be carried by an earthed train (earthed), flowing through an iron tunnel layer instead. This can cause electrolyte and even curve damage if the tunnel segments are not electrically bonded together. The problem is exacerbated because the backflow also has a tendency to flow through nearby iron pipes that form waterways and gases. Some of them, especially the Victorian mother who preceded the London subway, were not built to carry the current and did not have sufficient electrical ties between the pipe segments. The four rail system solves the problem. Although the supply has artificial artificial point of the earth, this connection originates by using a resistor that ensures that wild earth currents are stored to manageable levels. Power-only rails can be mounted on highly insulated ceramic chairs to minimize current leakage, but it is not possible to run a rail that should sit on a stronger metal seat to carry train loads. However, elastomeric rubber pads placed between the rails and seats can now solve part of the problem by isolating the running rail from the reverse current should there be leakage through the running rail.
On the trajectory divided by the London Underground with the third national railway track (the Bakerloo line and the District both have those sections), the central rail is connected to the ongoing rail, allowing both types of trains to operate, at a compromise voltage of 660 V The underground train passes from one part to another with speed; electrical connections and edge line resistance separating the two types of supply. These routes were initially powered only by the four-rail system by LNWR before the National Rail train was re-paired to their standard three-track system to simplify the use of rolling stock.
The fourth train sometimes operates on the third national rail system. To do so, the middle rail shoes are tied to the wheels. This bond must be removed before re-operation on the fourth rail, to avoid short circuit.
Linear motor
Four rail system
The four rail system consists of two running rails, a third rail and a thin aluminum strip between the running rails.
Five rail system
In the case of Scarborough Line 3, the third and fourth rails are outside the track and the fifth rail is an aluminum row between the running rails.
The rubber tyred system
Several lines of Paris MÃÆ'Â tro tro in France operate with a four-rail power scheme. The train moves with a rolled rubber tire on a pair of narrow rolls made of steel and, in some places, from concrete. Since the tires do not backflow, the two guiding rods provided outside the 'coils' path become, in a sense, the third and fourth rails which each provide 750 V DC, so at least electrically it is a four-track scheme. Each set of truck-powered wheels carries a traction motor. Side sliding (side running) contact shoe takes the current from the vertical face of each guide bar. The return of each traction motor, as well as each wagon, is affected by one contact shoe each that glide on top of each of the running rails. This and all other rubber-tyred metrics that have 1,435 mm ( 4Ã, ftÃ, 8 1 / 2 in ) track standard sizes between how the scrolls operate in the same way.
Alternating current
Railways and electric utilities use AC for the same reason: using transformers, which require air conditioning, to produce higher voltages. The higher the voltage, the lower the current for the same power, which reduces the loss of the line, thus allowing higher power to be transmitted.
Because the alternating current is used with high voltage, this electrification method is only used on the cable above the head, never on the third rail. Inside the locomotive, the transformer drives the voltage down for use by the traction motor and an additional load.
The initial advantage of AC is that the power-discharging resistor used in DC locomotives for speed control is not required in an AC locomotive: some taps on the transformer can provide various voltages. Voltage winding of a separate low-voltage transformer and a motor that drives the auxiliary machine. Recently, the development of very high-power semiconductors has led to classic "universal" AC/DC motors being replaced largely by a three-phase induction motor fed by variable frequency drivers, a special inverter that converts frequencies and voltages into controls. motor speed. These drives can run well in DC or AC of any frequency, and many modern electric locomotives are designed to handle different supply voltages and frequencies to simplify cross-border operations.
Low frequency alternating current
DC electric motors take turns, if equipped with polar laminated pieces, become universal motors because they can also operate on AC; reverses the current in the stator and the rotor does not reverse the motor. However, the current AC frequency distribution frequency standard 50 and 60 Hz causes difficulties with inductive reactance and eddy current losses, so many trains choose low AC frequencies to solve this problem. They must be converted from electric power by a generator motor or static inverter in a feeder substation or generated on special traction powerstation.
This low frequency is then made unnecessary by a high power locomotive rectifier that can convert AC frequency to DC: first rectifier of arc-mercury and then semiconductor rectifier. Some AC trains have been converted to standard network frequencies, but low frequencies are still widely used due to the cost of large concave appliances.
Five European countries, Germany, Austria, Switzerland, Norway and Sweden, have been standardized at 15 kV 16 2 / 3 Ã, Hz (parent frequency 50Ã, Hz divided by three) single phase AC. On October 16, 1995, Germany, Austria, and Switzerland changed from 16 2 / 3 Ã, Hz to 16.7 Ã, Hz which is no longer exactly one-third of the lattice frequency. This solves the overheating problem with the rotary converter used to generate some of this power from the network supply.
High voltage AC overhead system not only for national network of standard gauges. The meter gauges Rhaetian Railway (RhB) and Matterhorn Gotthard Bahn (MGB) neighbors operate at 11 kV at a frequency of 16.7 Hz. Practice has proven that Swiss and German 15 KV trains can operate under this lower voltage. The RhB started a 11 kV system test in 1913 on the Engadin line (St. Moritz-Scuol/Tarasp). The MGB constituents Furka Oberalp Bahn (FO) and Brig-Visp-Zermatt Bahn (BVZ) introduced their electrical services in 1941 and 1929 respectively, adopting a proven RhB system.
In the United States, 25 Hz, the commonly used industrial power frequency, is used on a 25 Hz Amtrak traction power system at 12 kV in the Northeast Corridor between Washington, DC and New York City and in the Keystone Corridor between Harrisburg, Pennsylvania and Philadelphia. The SEPTA 25 Hz traction power system uses the same 12 kV voltage at the catenary in Northeast Philadelphia. This allows the carriage to operate in both Amtrak and SEPTA power systems. In addition to having the same catenary voltage, the Amtrak and SEPTA power distribution systems are very different. The Amtrak power distribution system has a 138 kV transmission line that provides power to substations which then convert the voltage to 12 kV to feed the catenary system. The SEPTA power distribution system uses a 2: 1 autotransformer ratio system, with catenary fed to 12 kV and feeder feeds at 24 kV. New York, New Haven and Hartford Railroad used a 11 kV system between New York City and New Haven, Connecticut, which converted to 12.5 kV 60 Hz in 1987.
In London, Brighton and the South Coast Railway pioneered electricity on the outskirts of London, London Bridge to Victoria opened for traffic on December 1, 1909. Victoria to Crystal Palace via Balham and West Norwood opened in May 1911. Peckham Rye to West Norwood opened in June 1912. No further extensions were made because of the First World War. Two lines opened in 1925 under the Southern Railway which serves the Coulsdon North and Sutton railway stations. The lines are electrified at 6.7 â € <â €
The electrification of a three-phase AC railway was used in Italy, Switzerland and the United States at the beginning of the 20th century. Italy was the primary user, for a line in the northern Italian mountains from 1901 to 1976. The first line was the Burgdorf-Thun line in Switzerland (1899), and the Ferrovia della Valtellina line from Colico to Chiavenna and Tirano in Italy, powered in 1901 and 1902. Another line in which the three-phase system was used was the Simplon Tunnel in Switzerland from 1906 to 1930, and the Cascade Tunnel of the Great North Rail in the United States from 1909 to 1927.
The initial system uses low frequency ( 16 2 / 3 Ã, Hz), and relatively low voltage (3,000 or 3,600 volts) compared to AC systems later on. This system provides regenerative braking with power that is fed back to the system, making it particularly suitable for mountain trains that provide a supply network or other locomotives on a receiving line.
The three-phase system has serious losses that require at least two separate overhead conductors plus rail returns. Locomotives operate at one, two or four constant speeds. Most modern locomotives with variable frequency drivers can also perform regenerative braking on AC and DC systems and are not limited to constant speeds.
This system is still used on four mountain railways, using 725 to 3000Ã, V at 50 or 60 Hz: Corcovado Rack Railway in Rio de Janeiro, Brazil, Jungfraubahn and Gornergratbahn in Switzerland, and the Petit de la Rhune train in France.
Standard frequency alternating current
Only in 1950 after development in France (20 kV, then 25 kV) and former Soviet railway (25 kV) countries did single-phase single frequency fringe systems became widespread, despite the simplification of distribution systems that could use existing power supply networks.
The first attempt to use single-phase single-phase AC was made in Hungary as far back as 1923, by KÃÆ'¡lmÃÆ'¡n KandÃÆ'³ Hungary on the line between Budapest-Nyugati and Alag, using 16 kV at 50 Hz. Locomotives carry a four-pole phase turnaround converter that feeds single traction motors of polyphase induction type at 600 to 1,100? V. The number of poles on a 2,500 hp motor can be changed using a slip ring to run on any of the four syncs. speed. The test was a success, from 1932 to 1960s, the train on the Budapest-Hegyeshalom line (towards Vienna) regularly used the same system. A few decades after the Second World War, 16 kV was converted to Russia's 25Va kV system and then France.
Currently, some locomotives in this system use transformers and rectifiers to provide low voltage pulsed electrical currents to the motor. Speed ​​is controlled by switching winding faucets on the transformer. More sophisticated locomotives use thyristors or IGBT circuits to generate chopped or even variable frequency alternating current (AC) which is then supplied to AC induction traction motors.
This system is quite economical but has its drawbacks: the external power system phase is loaded unbalanced and there are significant electromagnetic interference generated as well as significant acoustic sound.
List of countries using a single-phase 25-kV ACÃ, 50Ã, Hz system can be found in the List of rail electrification systems. There are also several lines listed with 50Ã, kV (60Ã, Hz) electrification, especially long lines that isolate hauling coal or ore in the United States and Canada. The first line (1973) using 50 kV is Black Mesa and Lake Powell Railroad. In South Africa, the Sishen-Saldanha railway carrying iron ore uses 50 kV (50 Hz).
The United States generally uses 12.5 and 25 kV at 25 Hz or 60 Hz. 25 kV, 60 Hz AC is the preferred system for new high-speed and long-distance trains, even if trains use different systems for existing trains.
To prevent the risk of supply outside the mixing phase, the sections of the channels flowed from different feed stations must be kept isolated. This is achieved by Neutral (also known as Broken Phase ), usually provided at the feeder station and between the two though, usually, only half are used at any time, others provided to allow feeder stations to be turned off and power supplied from adjacent feed stations. The Neutral section usually consists of an earthed wire section separated from living cables on both sides by insulating material, usually ceramic beads, designed in such a way that the pantograph runs smoothly from one part to another. The earthed part prevents the arc being pulled from one part directly to the other, since the voltage difference may be higher than the normal system voltage if the live parts are in different phases and the protective circuit breakers may not be able to safely interfere with the current to flow. To prevent the risk of the arc being pulled from one section of the wire to the earth, when passing through the neutral parts, the train must slide and the circuit breaker must be open. In many cases, this is done manually by the driver. To help them, a warning board is provided just before the neutral and previous warning parts of some previous distance. An additional board is then provided after a neutral section to notify the driver to re-close the circuit breaker, although the driver should not do this until the rear pantograph has passed through this board. In the UK, a system known as Automatic Power Control (APC) automatically opens and closes the circuit breaker, this is achieved by using a permanent magnet set on the side of the track that communicates with the detector on the train. The only action required by the driver is to turn off the power and the beach and therefore a warning board is still provided in and on the approach to the neutral section.
On the French high-speed rail, High Speed ​​Tunnel links 1 English Channel and in the Channel Tunnel, the neutral part is negotiated automatically.
In the Japanese Shinkansen line, any switched on-land portion is enabled instead of a neutral part. This section detects the train running inside the section and automatically switches the power supply within 0.3 s, which eliminates the need to turn off the power at any time.
Non-contact system
It is possible to supply electricity to the electric train with inductive coupling. This allows the use of high-voltage rails, insulated, conductors. Such a system was patented in 1894 by Nikola Tesla, US Patent 514972. It required the use of high-frequency alternating currents. Tesla did not specify the frequency but George Trinkaus pointed out that about 1,000 Hz would be possible.
Inductive coupling is widely used in low power applications, such as rechargeable and newer electric toothbrushes, cell phones and usable computing devices (inductive charging). The contactless technology for rail vehicles is currently being marketed by Bombardier as PRIMOVE.
Energy efficiency
Electricity vs Diesel
The electric train does not need to carry the main driving load, transmission and fuel. This is partially offset by the load of electrical equipment.
Regenerative braking returns power to the electrification system so it can be used elsewhere, by other trains on the same system or returned to the public grid. This is very useful in mountainous areas where loaded trains have to go down a long class.
Central station electricity can often be generated with higher efficiency than a moving machine/generator. While the efficiency of power generation and diesel locomotive generation is more or less the same in nominal regimes, diesel motors lower the efficiency in non-nominal regimes with low power while if the power plant needs to produce less power it will turn off the efficient generator, thereby increasing efficiency. Electric trains can save energy (compared to diesel) with regenerative braking and do not need to consume energy with idling just as diesel locomotives do when they stop or glide. However, the electric rolling stock can run the cooling blower when it stops or slides, thus consuming energy.
Large fossil fuel power plants operate at high efficiency, and can be used for district heating or to generate district cooling, leading to higher total efficiency.
Unsuitable energy sources for mobile power plants, such as nuclear power, renewable hydro power, or wind power can be used. According to widely accepted global energy reserves statistics, liquid fuel stocks are much less than gas and coal (respectively at 42, 167 and 416 years). Most countries with large rail networks have no significant oil reserves and those who do, such as the United States and Britain, have spent most of their reserves and experienced declining oil production for decades. Therefore, there are also strong economic incentives to replace other fossil fuels. Rail electrification is often regarded as an important route to the reform of consumption patterns. However, there is no reliable and readily available research to assist in the rational public debate on this critical issue, although there are Soviet studies which were not translated from the 1980s.
AC vs DC for main stream
The modern electrification system takes the AC energy from the power grid that is sent to the locomotive and converted to DC voltage for use by traction motors. These motors can be DC motors that directly use DC or they may be a 3-phase AC motor that requires further conversion from DC to AC 3-phase (using power electronics). Thus both systems are faced with the same task: converting and transporting high voltage AC from power grid to low voltage DC in locomotive. The difference between an AC and DC electrification system is located where the air conditioner is converted to DC: in a substation or on a train. The cost of energy efficiency and infrastructure determines which one is used on the network, although this is often fixed due to a pre-existing electrification system. Both the transmission and conversion of electrical energy involve losses: ohmic losses in cable and power electronics, loss of magnetic field in transformer and leveling of reactor (inductor). Power conversion for DC systems occurs mainly in railroads where heavy, heavy, and more efficient hardware can be used compared to AC systems where conversions occur over locomotives where space is limited and losses are significantly higher. Also, the energy used to blow air to cool transformers, power electronics (including rectifiers), and other conversion hardware must be accounted for.
Comparison with diesel traction
Electric locomotives can be easily built with greater power output than most diesel locomotives. For passenger operations, it is possible to provide sufficient power with diesel engines (see eg 'ICE TD') but, at higher speeds, this proves costly and impractical. Therefore, almost all high-speed trains are electric. The power of high electric locomotives also gives them the ability to pull things at a higher rate than the gradients; in traffic conditions this mixture increases capacity when the time between trains can be reduced. Higher strengths of electric locomotives and electrification can also be a cheaper alternative to new and less steep railways if rail weight is increased on a system.
On the other hand, electrification may not be suitable for lines with low traffic frequency, as lower rail costs can be overwhelmed by the high cost of electrification infrastructure. Therefore, most long-haul lanes in developing countries or rarely residents are not powered by the relatively low frequency of trains.
Channel maintenance costs can be increased by electrification, but many systems claim lower costs due to reduced wear caused by lighter rolling stock. There are some additional maintenance costs associated with electrical equipment around the track, such as power sub-stations and catenary cables themselves, but, if there is enough traffic, the lines are reduced and especially lower machine maintenance and operating costs exceed maintenance costs this is significant.
Network effect is a big factor with electrification. When converting paths into electricity, connections with other lines should be considered. Some electrification is then removed because of traffic through a non-electrification path. If through traffic is to get any benefit, it takes time to change the machine switch to make connections or expensive double mode machines should be used. This is mostly a problem for long distance travel, but many lines are dominated by traffic from long-distance freight trains (usually running coal, ore, or containers to or from the port). Theoretically, these trains can enjoy dramatic savings through electrification, but it can be too costly to extend electrification to remote areas, and unless the entire grid is electricity, companies often find that they need to continue using diesel trains even if the electrical portion. Increased demand for more efficient container traffic when using a double-stack car also has a network effect problem with existing electrification due to inadequate loading of power lines on this train, but electrification can be built or modified to have sufficient permits, at cost additional.
In addition, there is a connection problem between different electrical services, especially connecting the intercity with the electrically flowable parts for commuter traffic, but also between commuter lines built with different standards. This can cause the electrification of certain connections to be very expensive simply because of their implications on the connected part. Many lines are coated with several electrification standards for different trains to avoid having to replace the rolling stock on the track. Obviously, this necessitates certain connection economics to be more attractive and this has prevented the complete electrification of many paths. In some cases, there are diesel trains running along fully electrically powered routes and this can be caused by a mismatch of electrification standards along the route.
In 2006, 240,000 km (150,000 mi) (25% of the length) of the world's railroad networks were powered and 50% of all rail transport was carried by electric traction.
In 2012 for electrically powered kilometers, China surpassed Russia, making it the first place in the world with more than 48,000 km (30,000 mi) of electricity. Trailing behind China is Russia 43,300 km (26,900 mi), India 30,012 km (18,649 mi), Germany 21,000 km (13,000 mi), Japan 17,000 km (11,000 mi), and France 15,200 km (9,400Ã, mi).
Spark effect
The new electrification line often shows "spark effect", where electrification on the passenger train system leads to a significant jump in patronage/revenue. The reasons may include electric trains seen as more modern and interesting to ride, faster and smoother service, and the fact that electrification often goes hand in hand with public infrastructure and turns inventory turnover, leading to better service quality (in theoretical way can also be achieved by making similar improvements without electrification). Whatever the cause of the spark effect, it has been well proven for a number of routes that have been powered for decades.
Diesel Islands
Source of the article : Wikipedia
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