Railway_electrification_system

qas: question: What is of the factors the capital cost of electrification system depends on?
answers: text: maintenance
is_impossible: no

question: How do some locomotives function in order to be more flexible in operation?
answers: text: can switch to different supply voltages
is_impossible: no

question: What is the main disadvantage of railway electrification?
answers: text: significant capital expenditure
is_impossible: no

question: What are two types of revenue obtained through railway transportation?
answers: text: freight and passenger traffic
is_impossible: no

question: What system supplies nuclear power to railway trains?
is_impossible: yes

question: What requires insignificant capital expenditure?
is_impossible: yes

question: The same systems are used for both urban and intercity what?
is_impossible: yes

question: All electric locomotives can switch to different supply voltages to allow for what?
is_impossible: yes

question: A railway electrification system supplies power to trains and trams with an on-board what?
is_impossible: yes

question: What is a major factor whn it comes to electrification?
is_impossible: yes

question: What is the solution many lines came up with in order to avoid replacing present rolling stock?
is_impossible: yes

question: How many narrow-gauge lines in Slovakia?
is_impossible: yes
context: A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply. Electrification has many advantages but requires significant capital expenditure. Selection of an electrification system is based on economics of energy supply, maintenance, and capital cost compared to the revenue obtained for freight and passenger traffic. Different systems are used for urban and intercity areas; some electric locomotives can switch to different supply voltages to allow flexibility in operation.

qas: question: What is used to haul passengers cars?
answers: text: electric locomotives
is_impossible: no

question: How is electricity being generated for electric locomotives?
answers: text: generating stations
is_impossible: no

question: What entity provides distribution lines, switches and transformers?
answers: text: railway
is_impossible: no

question: Which railways haul passengers and freight in the same cars?
is_impossible: yes

question: What is typically generated in small generating stations?
is_impossible: yes

question: All electric railways have their own dedicated what?
is_impossible: yes

question: Very few purchase power from whom?
is_impossible: yes

question: What is generated in relatively inefficient stations?
is_impossible: yes

question: Who started trials of the 111kV system?
is_impossible: yes

question: What can be very inexpensive?
is_impossible: yes

question: What kind of losses take place in transformers and inductors during conversion/transmission process?
is_impossible: yes
context: Electric railways use electric locomotives to haul passengers or freight in separate cars or electric multiple units, passenger cars with their own motors. Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches and transformers.

qas: question: What is the principal alternative to electric railways?
answers: text: diesel engine
is_impossible: no

question: What locomotives are usually more reliable?
answers: text: Electric locomotives
is_impossible: no

question: What do some electric traction systems provide?
answers: text: regenerative braking
is_impossible: no

question: What type of fuel do diesel locomotives use?
answers: text: petroleum
is_impossible: no

question: What is one of the sources electricity is being generated from?
answers: text: geothermal
is_impossible: no

question: What does not offer better emissions efficiency?
is_impossible: yes

question: Electricity is generated from many sources that do produce carbon what?
is_impossible: yes

question: electricity is generated from non-renewable forms including?
is_impossible: yes

question: Which locomotives have no global emissions?
is_impossible: yes

question: All electric traction systems provide what kind of braking?
is_impossible: yes

question: The cost of diesel was 2.5 times more than what? 
is_impossible: yes

question: Where in India line has been converted to AC?
is_impossible: yes

question: Why overhead wires are not being widely used?
is_impossible: yes
context: In comparison to the principal alternative, the diesel engine, electric railways offer substantially better energy efficiency, lower emissions and lower operating costs. Electric locomotives are usually quieter, more powerful, and more responsive and reliable than diesels. They have no local emissions, an important advantage in tunnels and urban areas. Some electric traction systems provide regenerative braking that turns the train's kinetic energy back into electricity and returns it to the supply system to be used by other trains or the general utility grid. While diesel locomotives burn petroleum, electricity is generated from diverse sources including many that do not produce carbon dioxide such as nuclear power and renewable forms including hydroelectric, geothermal, wind and solar.

qas: question: What issue can complicate electric railway service?
answers: text: different supply voltages and frequencies,
is_impossible: no

question: What is a safety hazard to track workers?
answers: text: voltages on contact wires
is_impossible: no

question: What is a safer alternative to third rails?
answers: text: Overhead wires
is_impossible: no

question: Why overhead wires are not being widely used?
answers: text: considered unsightly.
is_impossible: no

question: Advantages of electric traction include?
is_impossible: yes

question: All regions use the same supply voltages and?
is_impossible: yes

question: Lethal voltages on contact wires and third rails are non a safety hazard for whom?
is_impossible: yes

question: Third rails are considered safer than overhead wires, but are considered what?
is_impossible: yes

question: Energy-efficiency increases as what goes up?
is_impossible: yes

question: What uses a 1:2 ratio autotransformer?
is_impossible: yes

question: Overhead wires are considered physically very what?
is_impossible: yes
context: Disadvantages of electric traction include high capital costs that may be uneconomic on lightly trafficked routes; a relative lack of flexibility since electric trains need electrified tracks or onboard supercapacitors and charging infrastructure at stations; and a vulnerability to power interruptions. Different regions may use different supply voltages and frequencies, complicating through service. The limited clearances available under catenaries may preclude efficient double-stack container service. The lethal voltages on contact wires and third rails are a safety hazard to track workers, passengers and trespassers. Overhead wires are safer than third rails, but they are often considered unsightly.

qas: question: What is speed limit for railways?
answers: text: variable speeds
is_impossible: no

question: Why is DC motor being used more than AC type?
answers: text: conversion was not well developed
is_impossible: no

question: What are two types of railway transportation still use DC motor?
answers: text: rapid transit (subways) and trams
is_impossible: no

question: What must operate at constant speeds?
is_impossible: yes

question: Speed was controlled by disconnecting the traction motors where?
is_impossible: yes

question: A brush-type BC motor operated at what speeds?
is_impossible: yes

question: All early electrified motors used what type of motor?
is_impossible: yes

question: Varying the transition motors' fields helped control what?
is_impossible: yes

question: Who was the major user of railway electrification in the nineteenth century?
is_impossible: yes

question: Why some lines of Paris Metro have to operate on a four-rail system?
is_impossible: yes

question: What type of system does London Underground use?
is_impossible: yes
context: Railways must operate at variable speeds. Until the mid 1980s this was only practical with the brush-type DC motor, although such DC can be supplied from an AC catenary via on-board electric power conversion. Since such conversion was not well developed in the late 19th century and early 20th century, most early electrified railways used DC and many still do, particularly rapid transit (subways) and trams. Speed was controlled by connecting the traction motors in various series-parallel combinations, by varying the traction motors' fields, and by inserting and removing starting resistances to limit motor current.

qas: question: Why do motors have little space for insulation?
answers: text: low voltage ratings
is_impossible: no

question: What is most common volatage range used by railway system?
answers: text: below 1 kV
is_impossible: no

question: Why 1kV voltage is almost always used by rail systems?
answers: text: safety reasons
is_impossible: no

question: Which system uses higher voltages?
answers: text: overhead wires
is_impossible: no

question: Is "low" voltage used by trains safe for people?
answers: text: lethal
is_impossible: no

question: How many volts can be considered nonlethal when touched?
is_impossible: yes

question: Motors have a lot of room for electrical what?
is_impossible: yes

question: What can step down DC voltages?
is_impossible: yes

question: Fifth (and sixth) railsystems use what voltages for safety reasons?
is_impossible: yes

question: What has high voltage ratings?
is_impossible: yes

question: Above what speed can reliable contact between the shoe and the rail be maintained?
is_impossible: yes

question: When was overhead wires system being used for the first time in UK?
is_impossible: yes

question: Why the commuter lines built to different standards can cause be complicated?
is_impossible: yes
context: Motors have very little room for electrical insulation so they generally have low voltage ratings. Because transformers (prior to the development of power electronics) cannot step down DC voltages, trains were supplied with a relatively low DC voltage that the motors can use directly. The most common DC voltages are listed in the previous section. Third (and fourth) rail systems almost always use voltages below 1 kV for safety reasons while overhead wires usually use higher voltages for efficiency. ("Low" voltage is relative; even 600 V can be instantly lethal when touched.)

qas: question: What type of electric power garantees lesser loss?
answers: text: DC
is_impossible: no

question: Which type of supply for electric motors creates electromagnetic radiation?
answers: text: AC
is_impossible: no

question: What can electromagnetic radiation interfere with?
answers: text: signalling and communications
is_impossible: no

question: Which type of power does require three-phase transmission?
answers: text: AC
is_impossible: no

question: Where was an experimental 6kV DC railway built?
answers: text: the Soviet Union
is_impossible: no

question: Railroad operators have shown little interest in returning to what?
is_impossible: yes

question: What is being used on all bulk power transmission lines?
is_impossible: yes

question: DC can supply variable power with a single underground what?
is_impossible: yes

question: What requires a four-phase transmission with at least two underground wires?
is_impossible: yes

question: How many railroads have tried 4-phase?
is_impossible: yes

question: What is a key advantage to the fifth rail system?
is_impossible: yes

question: What specification is similar for both Amtrak and Septa systems?
is_impossible: yes

question: What is considered an unimportant factor for subway systems?
is_impossible: yes
context: There has, however, been interest among railroad operators in returning to DC use at higher voltages than previously used. At the same voltage, DC often has less loss than AC, and for this reason high-voltage direct current is already used on some bulk power transmission lines. DC avoids the electromagnetic radiation inherent with AC, and on a railway this also reduces interference with signalling and communications and mitigates hypothetical EMF risks. DC also avoids the power factor problems of AC. Of particular interest to railroading is that DC can supply constant power with a single ungrounded wire. Constant power with AC requires three-phase transmission with at least two ungrounded wires. Another important consideration is that mains-frequency 3-phase AC must be carefully planned to avoid unbalanced phase loads. Parts of the system are supplied from different phases on the assumption that the total loads of the 3 phases will even out. At the phase break points between regions supplied from different phases, long insulated supply breaks are required to avoid them being shorted by rolling stock using more than one pantograph at a time. A few railroads have tried 3-phase but its substantial complexity has made single-phase standard practice despite the interruption in power flow that occurs twice every cycle. An experimental 6 kV DC railway was built in the Soviet Union.

qas: question: What is most common voltage for DC supply?
answers: text: 1,500 V
is_impossible: no

question: How many narrow-gauge lines in Slovakia?
answers: text: two
is_impossible: no

question: What railway line is DC being used in Portugal?
answers: text: the Cascais Line
is_impossible: no

question: Where in India line has been converted to AC?
answers: text: Mumbai area
is_impossible: no

question: In Romania, there are two narrow-gauge lines where?
is_impossible: yes

question: There is a hog railway located where?
is_impossible: yes

question: The Cascade Line is located where?
is_impossible: yes

question: 1,500 V DC is used in what district in Connecticut?
is_impossible: yes

question: The South Shore Line suburb line uses what?
is_impossible: yes

question: The diesel train can save energy by regenerative what?
is_impossible: yes

question: Why DC system can effect the speed of trains?
is_impossible: yes

question: What can not limit the size and speed of trains?
is_impossible: yes
context: 1,500 V DC is used in the Netherlands, Japan, Republic Of Indonesia, Hong Kong (parts), Republic of Ireland, Australia (parts), India (around the Mumbai area alone, has been converted to 25 kV AC like the rest of India), France (also using 25 kV 50 Hz AC), New Zealand (Wellington) and the United States (Chicago area on the Metra Electric district and the South Shore Line interurban line). In Slovakia, there are two narrow-gauge lines in the High Tatras (one a cog railway). In Portugal, it is used in the Cascais Line and in Denmark on the suburban S-train system.

qas: question: What voltage is being used in railway system of South Africa and Chile?
answers: text: 3 kV DC
is_impossible: no

question: Besides using 3kV DC what other power type is used in the former Soviet Union countries?
answers: text: 25 kV 50 Hz AC
is_impossible: no

question: What was New Jersey Transit called before?
answers: text: Western Railroad
is_impossible: no

question: What does the railway system of US use DC or AC?
answers: text: AC
is_impossible: no

question: What was formally used by the Mississippi Road?
is_impossible: yes

question: What is used by the current Soviet Union countries?
is_impossible: yes

question: New York transit in the United States uses what?
is_impossible: yes

question: The Kukuburra suburban railway is located where?
is_impossible: yes

question: The Kolkata suburban railway in India converted from what?
is_impossible: yes

question: How long did the AC system last in northern Italy?
is_impossible: yes

question: What can often be generated with a lower efficiency?
is_impossible: yes

question: What type is mostly used third rail or overhead wires?
is_impossible: yes
context: 3 kV DC is used in Belgium, Italy, Spain, Poland, the northern Czech Republic, Slovakia, Slovenia, South Africa, Chile, and former Soviet Union countries (also using 25 kV 50 Hz AC). It was formerly used by the Milwaukee Road from Harlowton, Montana to Seattle-Tacoma, across the Continental Divide and including extensive branch and loop lines in Montana, and by the Delaware, Lackawanna & Western Railroad (now New Jersey Transit, converted to 25 kV AC) in the United States, and the Kolkata suburban railway (Bardhaman Main Line) in India, before it was converted to 25 kV 50 Hz AC.

qas: question: What type is mostly used third rail or overhead wires?
answers: text: overhead wires
is_impossible: no

question: Is trird rail system being used exclusively with AC or DC ?
answers: text: DC distribution
is_impossible: no

question: What depth does the alternating current penetrate in a steel rail?
answers: text: skin depth
is_impossible: no

question: What is physically more compact tird rail or overhead wires?
answers: text: Third rail
is_impossible: no

question: What is more prefferable for subway lines?
answers: text: Third rail
is_impossible: no

question: All electrical systems use what kind of wires?
is_impossible: yes

question: The third rail operates over what voltage?
is_impossible: yes

question: Overhead wires are more compact than third rail and can be used for what?
is_impossible: yes

question: What is considered an unimportant factor for subway systems?
is_impossible: yes

question: Overhead wires are considered physically very what?
is_impossible: yes

question: What can not limit the size and speed of trains?
is_impossible: yes

question: Which system is now upgrading their fifth rail system to 750v DC?
is_impossible: yes

question: What was formally used by the Mississippi Road?
is_impossible: yes
context: Most electrification systems use overhead wires, but third rail is an option up to about 1,200 V. Third rail systems exclusively use DC distribution. The use of AC is not feasible because the dimensions of a third rail are physically very large compared with the skin depth that the alternating current penetrates to (0.3 millimetres or 0.012 inches) in a steel rail). This effect makes the resistance per unit length unacceptably high compared with the use of DC. Third rail is more compact than overhead wires and can be used in smaller-diameter tunnels, an important factor for subway systems.

qas: question: Why DC system can effect the speed of trains?
answers: text: low voltages
is_impossible: no

question: Can DC systems use low-level platform?
answers: text: cannot
is_impossible: no

question: Besides speed and size what else the low voltage of DC system can effect?
answers: text: air-conditioning
is_impossible: no

question: What is the speed limit for third rail system trains?
answers: text: 160 km/h
is_impossible: no

question: What can become unreliable if the speed exceeds the limit of 100 mph for DC system trains?
answers: text: contact between the shoe and the rail
is_impossible: no

question: DC systems are limited to relatively high what?
is_impossible: yes

question: The lowest speed of trains on third-rail systems is limited to what?
is_impossible: yes

question: Above what speed can reliable contact between the shoe and the rail be maintained?
is_impossible: yes

question: What can not limit the size and speed of trains?
is_impossible: yes

question: What is not a factor favoring overhead wires and high-voltage AC?
is_impossible: yes

question: A railway electrification system supplies power to trains and trams with an on-board what?
is_impossible: yes

question: Power conversion for an AC system takes place mainly in a what?
is_impossible: yes

question: Low-voltage AC overhead systems are not only for what?
is_impossible: yes
context: DC systems (especially third-rail systems) are limited to relatively low voltages and this can limit the size and speed of trains and cannot use low-level platform and also limit the amount of air-conditioning that the trains can provide. This may be a factor favouring overhead wires and high-voltage AC, even for urban usage. In practice, the top speed of trains on third-rail systems is limited to 100 mph (160 km/h) because above that speed reliable contact between the shoe and the rail cannot be maintained.

qas: question: What is the other name for the street trams?
answers: text: streetcars
is_impossible: no

question: Where is third rail situated in the street trams system?
answers: text: below street level
is_impossible: no

question: What area in US discontinued using overhead wires for streetcars in 1962?
answers: text: Washington, D.C.
is_impossible: no

question: What external and weather factors can effect conduit slot?
answers: text: leaves and snow
is_impossible: no

question: What are the main reasons the conduit lines were converted to overhead  wire system?
answers: text: cost and operating efficiency
is_impossible: no

question: All street trams use conduit what?
is_impossible: yes

question: What is accessed through a wide slot in the road?
is_impossible: yes

question: In what neighborhood in New York have the abandoned tracks not been paved over?
is_impossible: yes

question: An advantage of conduit collection is much high what?
is_impossible: yes

question: Cars on all lines have been converted to overhead wire in what city?
is_impossible: yes

question: During the Second World War, the 16 kV was changed to what?
is_impossible: yes

question: What year could be marked as year when electric railways more efficient than diesel ones?
is_impossible: yes

question: Low-voltage AC overhead systems are not only for what?
is_impossible: yes
context: Some street trams (streetcars) used conduit third-rail current collection. The third rail was below street level. The tram picked up the current through a plough (U.S. "plow") accessed through a narrow slot in the road. In the United States, much (though not all) of the former streetcar system in Washington, D.C. (discontinued in 1962) was operated in this manner to avoid the unsightly wires and poles associated with electric traction. The same was true with Manhattan's former streetcar system. The evidence of this mode of running can still be seen on the track down the slope on the northern access to the abandoned Kingsway Tramway Subway in central London, United Kingdom, where the slot between the running rails is clearly visible, and on P and Q Streets west of Wisconsin Avenue in the Georgetown neighborhood of Washington DC, where the abandoned tracks have not been paved over. The slot can easily be confused with the similar looking slot for cable trams/cars (in some cases, the conduit slot was originally a cable slot). The disadvantage of conduit collection included much higher initial installation costs, higher maintenance costs, and problems with leaves and snow getting in the slot. For this reason, in Washington, D.C. cars on some lines converted to overhead wire on leaving the city center, a worker in a "plough pit" disconnecting the plough while another raised the trolley pole (hitherto hooked down to the roof) to the overhead wire. In New York City for the same reasons of cost and operating efficiency outside of Manhattan overhead wire was used. A similar system of changeover from conduit to overhead wire was also used on the London tramways, notably on the southern side; a typical changeover point was at Norwood, where the conduit snaked sideways from between the running rails, to provide a park for detached shoes or ploughs.

qas: question: What year the "second generation" of tram system began to operate in France?
answers: text: 2003
is_impossible: no

question: When was the original system discontinued?
answers: text: 1958
is_impossible: no

question: How is the circuit of the third rail divided?
answers: text: energized segment
is_impossible: no

question: Does energized segment of third rail pose the threat to pedestrians if uncovered?
answers: text: no danger
is_impossible: no

question: An old approach to avoiding overhead wires is taken by what system?
is_impossible: yes

question: What system has been adopted in all sections of the new tram systems in Reims, France?
is_impossible: yes

question: When did the new tram system in Paris, France open?
is_impossible: yes

question: When did the new trans system in Achnor, France open?
is_impossible: yes

question: The circuit is left undivided in what system?
is_impossible: yes

question: Why some sections of Bakerloo and District lines were rewired to three-rail system?
is_impossible: yes

question: The third rail operates over what voltage?
is_impossible: yes

question: How can better service quality be achieved?
is_impossible: yes
context: A new approach to avoiding overhead wires is taken by the "second generation" tram/streetcar system in Bordeaux, France (entry into service of the first line in December 2003; original system discontinued in 1958) with its APS (alimentation par sol – ground current feed). This involves a third rail which is flush with the surface like the tops of the running rails. The circuit is divided into segments with each segment energized in turn by sensors from the car as it passes over it, the remainder of the third rail remaining "dead". Since each energized segment is completely covered by the lengthy articulated cars, and goes dead before being "uncovered" by the passage of the vehicle, there is no danger to pedestrians. This system has also been adopted in some sections of the new tram systems in Reims, France (opened 2011) and Angers, France (also opened 2011). Proposals are in place for a number of other new services including Dubai, UAE; Barcelona, Spain; Florence, Italy; Marseille, France; Gold Coast, Australia; Washington, D.C., U.S.A.; Brasília, Brazil and Tours, France.

qas: question: What type of system does London Underground use?
answers: text: four-rail system
is_impossible: no

question: What is the purpose of the forth rail?
answers: text: carries the electrical return
is_impossible: no

question: What is the volatage surge of the third rail of London Underground system?
answers: text: +420v DC
is_impossible: no

question: What is the voltage of the return rail?
answers: text: −210v DC
is_impossible: no

question: Where was the system similar to London Underground used as well?
answers: text: Milan
is_impossible: no

question: Which system in England is one of the few to use a five-rail system?
is_impossible: yes

question: On the London Underground, a bottom-contact rail is located where?
is_impossible: yes

question: A bottom-contact fourth rail is located where?
is_impossible: yes

question: Which system is now upgrading their fifth rail system to 750v DC?
is_impossible: yes

question: Many newer sections in tunnels are energised to what voltage?
is_impossible: yes

question: The Northeast Corridor connects Harrisburg, Pennsylvania and what city?
is_impossible: yes

question: How many narrow-gauge lines in Slovakia?
is_impossible: yes

question: Why the commuter lines built to different standards can cause be complicated?
is_impossible: yes
context: The London Underground in England is one of the few networks that uses a four-rail system. The additional rail carries the electrical return that, on third rail and overhead networks, is provided by the running rails. On the London Underground, a top-contact third rail is beside the track, energized at +420v DC, and a top-contact fourth rail is located centrally between the running rails at −210v DC, which combine to provide a traction voltage of 630v DC. London Underground is now upgrading its fourth rail system to 750v DC with a positive conductor rail energised to +500v DC and a negative conductor rail energised to -250v DC. However, many older sections in tunnels are still energised to 630v DC. The same system was used for Milan's earliest underground line, Milan Metro's line 1, whose more recent lines use an overhead catenary or a third rail.

qas: question: What is the crucial advantage of four-rail system?
answers: text: running rail carries any current
is_impossible: no

question: What danger can return currents cause?
answers: text: electrolytic damage
is_impossible: no

question: How did return current effect water and gas in iron pipes?
answers: text: water and gas mains
is_impossible: no

question: How are stray earth currents kept to a manageable levels? 
answers: text: by using resistors
is_impossible: no

question: What insures minimal current leak during power rails instalation?
answers: text: ceramic chairs
is_impossible: no

question: What is a key advantage to the fifth rail system?
is_impossible: yes

question: What can happen if the tunnel segments are electrically bonded together?
is_impossible: yes

question: What has a tendency to flow past nearby iron pipes forming the water and gas mains?
is_impossible: yes

question: What has a naturally created earth point?
is_impossible: yes

question: What does not have to be seated on stronger metal chairs?
is_impossible: yes

question: All regions use the same supply voltages and?
is_impossible: yes

question: Peckham Rye to Victoria opened when?
is_impossible: yes

question: What is the purpose of the forth rail?
is_impossible: yes
context: The key advantage of the four-rail system is that neither running rail carries any current. This scheme was introduced because of the problems of return currents, intended to be carried by the earthed (grounded) running rail, flowing through the iron tunnel linings instead. This can cause electrolytic damage and even arcing if the tunnel segments are not electrically bonded together. The problem was exacerbated because the return current also had a tendency to flow through nearby iron pipes forming the water and gas mains. Some of these, particularly Victorian mains that predated London's underground railways, were not constructed to carry currents and had no adequate electrical bonding between pipe segments. The four-rail system solves the problem. Although the supply has an artificially created earth point, this connection is derived by using resistors which ensures that stray earth currents are kept to manageable levels. Power-only rails can be mounted on strongly insulating ceramic chairs to minimise current leak, but this is not possible for running rails which have to be seated on stronger metal chairs to carry the weight of trains. However, elastomeric rubber pads placed between the rails and chairs can now solve part of the problem by insulating the running rails from the current return should there be a leakage through the running rails.

qas: question: What is the voltage shared two types of trains UK railroad system?
answers: text: 660 V
is_impossible: no

question: Why some sections of Bakerloo and District lines were rewired to three-rail system?
answers: text: to simplify rolling stock use
is_impossible: no

question: How did it become possible to share the voltage for different types of train?
answers: text: the centre rail is connected to the running rails
is_impossible: no

question: What joins the two types of supply?
is_impossible: yes

question: What was rewired to the standard four-rail system?
is_impossible: yes

question: What is the maximum voltage of the two UK rail systems?
is_impossible: yes

question: Above ground trains pass from one section to the other at what?
is_impossible: yes

question: The London Underground does not share tracks with whom?
is_impossible: yes

question: What is mostly an issue for short distance trips?
is_impossible: yes

question: How were the drivers warned to start coasting the train?
is_impossible: yes

question: Why the commuter lines built to different standards can cause be complicated?
is_impossible: yes
context: On tracks that London Underground share with National Rail third-rail stock (the Bakerloo and District lines both have such sections), the centre rail is connected to the running rails, allowing both types of train to operate, at a compromise voltage of 660 V. Underground trains pass from one section to the other at speed; lineside electrical connections and resistances separate the two types of supply. These routes were originally solely electrified on the four-rail system by the LNWR before National Rail trains were rewired to their standard three-rail system to simplify rolling stock use.

qas: question: Why some lines of Paris Metro have to operate on a four-rail system?
answers: text: rubber tyres
is_impossible: no

question: What was the solution for the return current problem in Paris Metro?
answers: text: two guide rails
is_impossible: no

question: What is required in order for the guide rails to operate properly?
answers: text: a single polarity supply
is_impossible: no

question: How train is able to turn around after each completed journey?
answers: text: reversing loops
is_impossible: no

question: Why was the reversing loop created?
answers: text: having to 'run around' the rest of the train
is_impossible: no

question: All lines of the Paris Metro in France operate on what?
is_impossible: yes

question: What runs on metal tyres?
is_impossible: yes

question: Why were many of the original loops kept?
is_impossible: yes

question: What type of tyres conduct the return current?
is_impossible: yes

question: What runs on a pair of wide roadways made of steel?
is_impossible: yes

question: Which system is now upgrading their fifth rail system to 750v DC?
is_impossible: yes

question: What is the main advantage of an induction motor?
is_impossible: yes

question: Above what speed can reliable contact between the shoe and the rail be maintained?
is_impossible: yes
context: A few lines of the Paris Métro in France operate on a four-rail power scheme because they run on rubber tyres which run on a pair of narrow roadways made of steel and, in some places, concrete. Since the tyres do not conduct the return current, the two guide rails provided outside the running 'roadways' double up as conductor rails, so at least electrically it is a four-rail scheme. One of the guide rails is bonded to the return conventional running rails situated inside the roadway so a single polarity supply is required. The trains are designed to operate from either polarity of supply, because some lines use reversing loops at one end, causing the train to be reversed during every complete journey. The loop was originally provided to save the original steam locomotives having to 'run around' the rest of the train saving much time. Today, the driver does not have to change ends at termini provided with such a loop, but the time saving is not so significant as it takes almost as long to drive round the loop as it does to change ends. Many of the original loops have been lost as lines were extended.

qas: question: What was a disadvantage of DC system?
answers: text: power-wasting resistors
is_impossible: no

question: How can different range of voltages be supplied for AC locomotives?
answers: text: multiple taps on the transformer
is_impossible: no

question: What taps can provide lighting supply?
answers: text: low-voltage transformer windings
is_impossible: no

question: What will AC/DC motor be replaced with?
answers: text: three-phase induction motor
is_impossible: no

question: What is the main advantage of an induction motor?
answers: text: can run equally well on DC or AC of any frequency
is_impossible: no

question: What was an early disadvantage of AC?
is_impossible: yes

question: One taps on the transformer can supply what?
is_impossible: yes

question: The development of low power semiconductors caused what?
is_impossible: yes

question: No modern electric locomotives are designed to handle what?
is_impossible: yes

question: Combined low-voltage transformer windings supply what?
is_impossible: yes

question: Due to the inefficient generation of electricity in the US, diesel traction was twice as energy efficient in what year?
is_impossible: yes

question: What type of system does London Underground use?
is_impossible: yes

question: Who started trials of the 111kV system?
is_impossible: yes
context: An early advantage of AC is that the power-wasting resistors used in DC locomotives for speed control were not needed in an AC locomotive: multiple taps on the transformer can supply a range of voltages. Separate low-voltage transformer windings supply lighting and the motors driving auxiliary machinery. More recently, the development of very high power semiconductors has caused the classic "universal" AC/DC motor to be largely replaced with the three-phase induction motor fed by a variable frequency drive, a special inverter that varies both frequency and voltage to control motor speed. These drives can run equally well on DC or AC of any frequency, and many modern electric locomotives are designed to handle different supply voltages and frequencies to simplify cross-border operation.

qas: question: How can DC motor turn universal?
answers: text: if fitted with laminated pole pieces
is_impossible: no

question: What problems did AC distribution cause?
answers: text: inductive reactance and eddy current losses
is_impossible: no

question: How do railways try to solve the problem of inductive reactance of AC system?
answers: text: low AC frequencies
is_impossible: no

question: How can low frequencies be obtained?
answers: text: converted from utility power
is_impossible: no

question: Reversing the current in both stator and rotor also reverses what?
is_impossible: yes

question: Many railways choose high AC frequencies to overcome what?
is_impossible: yes

question: The now-standard DC frequencies are what?
is_impossible: yes

question: The distribution frequencies of 60 and 70 Hz caused what?
is_impossible: yes

question: Many railways choose low DC what?
is_impossible: yes

question: What line used the overhead wire system first Victoria to Crystal Palace or Peckham Rye to West Noorwood?
is_impossible: yes

question: What is the maximum voltage of the two UK rail systems?
is_impossible: yes

question: A "sparks effect" is often seen on old lines which are what?
is_impossible: yes
context: DC commutating electric motors, if fitted with laminated pole pieces, become universal motors because they can also operate on AC; reversing the current in both stator and rotor does not reverse the motor. But the now-standard AC distribution frequencies of 50 and 60 Hz caused difficulties with inductive reactance and eddy current losses. Many railways chose low AC frequencies to overcome these problems. They must be converted from utility power by motor-generators or static inverters at the feeding substations or generated at dedicated traction powerstations.

qas: question: How did non-standard gauge trains start to operate with high-voltage AC?
answers: text: adopting the already proven RhB system.
is_impossible: no

question: When was the first trail of RhB system tested?
answers: text: 1913
is_impossible: no

question: Low-voltage AC overhead systems are not only for what?
is_impossible: yes

question: Which European trains can operate under high voltages?
is_impossible: yes

question: The MAB consisted of whom?
is_impossible: yes

question: Who started trials of the 111kV system?
is_impossible: yes

question: When did the RhB start trials of the 11 kV system on the Rhaetian line?
is_impossible: yes

question: What must be considered when converting lines from electric?
is_impossible: yes

question: The distribution frequencies of 60 and 70 Hz caused what?
is_impossible: yes

question: What line used the overhead wire system first Victoria to Crystal Palace or Peckham Rye to West Noorwood?
is_impossible: yes
context: High-voltage AC overhead systems are not only for standard gauge national networks. The meter gauge Rhaetian Railway (RhB) and the neighbouring Matterhorn Gotthard Bahn (MGB) operate on 11 kV at 16.7 Hz frequency. Practice has proven that both Swiss and German 15 kV trains can operate under these lower voltages. The RhB started trials of the 11 kV system 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 electric services in 1941 and 1929 respectively, adopting the already proven RhB system.

qas: question: What frequency was typically used on US Amtrak?
answers: text: 25 Hz
is_impossible: no

question: What voltage does SEPTA system use?
answers: text: 12 kV voltage
is_impossible: no

question: What specification is similar for both Amtrak and Septa systems?
answers: text: catenary voltage
is_impossible: no

question: When was a 11kV system of NY, New Haven and Hartford was converted to 12.5 kV?
answers: text: 1987
is_impossible: no

question: The Northeast Corridor connects Harrisburg, Pennsylvania and what city?
is_impossible: yes

question: The Keystone Corridor connects Washington, D.C. and what city?
is_impossible: yes

question: What uses a 1:2 ratio autotransformer?
is_impossible: yes

question: When was the New York, New Haven and Hartford railroad converted to a 11 kV system?
is_impossible: yes

question: What uses a catenary fed at 24 kV?
is_impossible: yes

question: How can electric train be more energy efficient?
is_impossible: yes

question: What is the purpose of the forth rail?
is_impossible: yes

question: Electricity is generated from many sources that do produce carbon what?
is_impossible: yes
context: In the United States, 25 Hz, a once-common industrial power frequency is used on Amtrak's 25 Hz traction power system at 12 kV on the Northeast Corridor between Washington, D.C. and New York City and on the Keystone Corridor between Harrisburg, Pennsylvania and Philadelphia. SEPTA's 25 Hz traction power system uses the same 12 kV voltage on the catenary in Northeast Philadelphia. This allows for the trains to operate on both the Amtrak and SEPTA power systems. Apart from having an identical catenary voltage, the power distribution systems of Amtrak and SEPTA are very different. The Amtrak power distribution system has a 138 kV transmission network that provides power to substations which then transform the voltage to 12 kV to feed the catenary system. The SEPTA power distribution system uses a 2:1 ratio autotransformer system, with the catenary fed at 12 kV and a return feeder wire fed at 24 kV. The New York, New Haven and Hartford Railroad used an 11 kV system between New York City and New Haven, Connecticut which was converted to 12.5 kV 60 Hz in 1987.

qas: question: When was overhead wires system being used for the first time in UK?
answers: text: 1 December 1909
is_impossible: no

question: What line used the overhead wire system first Victoria to Crystal Palace or Peckham Rye to West Noorwood?
answers: text: Victoria to Crystal Palace
is_impossible: no

question: What was the cause of lines not being extended?
answers: text: the First World War
is_impossible: no

question: What voltage was used in the two lines opened in 1925 of Southern Railway?
answers: text: 6.7 kV 25 Hz
is_impossible: no

question: When did the UK pioneer overhead electrification of its urban lines?
is_impossible: yes

question: Peckham Rye to Victoria opened when?
is_impossible: yes

question: Because of the Second World War, what was not completed?
is_impossible: yes

question: Three lines under the Southern Railway opened in what year?
is_impossible: yes

question: All lines were converted to DC fourth rail in what year?
is_impossible: yes

question: What must operate at constant speeds?
is_impossible: yes

question: Who started trials of the 111kV system?
is_impossible: yes

question: All early electrified motors used what type of motor?
is_impossible: yes
context: In the UK, the London, Brighton and South Coast Railway pioneered overhead electrification of its suburban lines in London, London Bridge to Victoria being opened to traffic on 1 December 1909. Victoria to Crystal Palace via Balham and West Norwood opened in May 1911. Peckham Rye to West Norwood opened in June 1912. Further extensions were not made owing to the First World War. Two lines opened in 1925 under the Southern Railway serving Coulsdon North and Sutton railway station. The lines were electrified at 6.7 kV 25 Hz. It was announced in 1926 that all lines were to be converted to DC third rail and the last overhead electric service ran in September 1929.

qas: question: What countries  used three-phase AC system in the the beginning of 20th century?
answers: text: Italy, Switzerland and the United States
is_impossible: no

question: What country was a bigger user compare to the three of them?
answers: text: Italy
is_impossible: no

question: Where did Italy start using the AC system?
answers: text: in the mountainous regions of northern Italy
is_impossible: no

question: How long did the AC system last in northern Italy?
answers: text: 1901 until 1976
is_impossible: no

question: How long did three-phase system operate in Cascade Tunnel?
answers: text: 1909 to 1927
is_impossible: no

question: Who was the major user of railway electrification in the nineteenth century?
is_impossible: yes

question: The four-phase system was used in what tunnel in Switzerland?
is_impossible: yes

question: The four-phase system was used in what tunnel in the US?
is_impossible: yes

question: The first four-way lines were in what country?
is_impossible: yes

question: The first four-way lines were created in what year?
is_impossible: yes

question: Elimination of what helped the efficiency of diesel traction to go up?
is_impossible: yes

question: What causes electric trains to waste energy?
is_impossible: yes

question: Where was an experimental 6kV DC railway built?
is_impossible: yes
context: Three-phase AC railway electrification was used in Italy, Switzerland and the United States in the early twentieth century. Italy was the major user, for lines in the mountainous regions of northern Italy from 1901 until 1976. The first lines were the Burgdorf-Thun line in Switzerland (1899), and the lines of the Ferrovia Alta Valtellina from Colico to Chiavenna and Tirano in Italy, which were electrified in 1901 and 1902. Other lines where the three-phase system were used were the Simplon Tunnel in Switzerland from 1906 to 1930, and the Cascade Tunnel of the Great Northern Railway in the United States from 1909 to 1927.

qas: question: What country has first tried to use single-phase AC?
answers: text: Hungary
is_impossible: no

question: What frequency did the line of Hungarian rail system used in 1923?
answers: text: 16 kV at 50 Hz
is_impossible: no

question: What type of the converter was used in hungarian locomotives of that time?
answers: text: four-pole rotating phase converter
is_impossible: no

question: How could the locomotives run on four speed levels?
answers: text: motor could be changed using slip rings
is_impossible: no

question: What system was adopted in Hungary after WWII?
answers: text: Russian
is_impossible: no

question: The number of poles on the 5,000 hp motor could be changed using what?
is_impossible: yes

question: The first attempt to use standard-frequency double-phase AC were made in what country? 
is_impossible: yes

question: The locomotives carrying a three-pole rotating phase converter could feed what?
is_impossible: yes

question: The first attempt to use standard-frequency double-phase AC were made in what year? 
is_impossible: yes

question: During the Second World War, the 16 kV was changed to what?
is_impossible: yes

question: What year the "second generation" of tram system began to operate in France?
is_impossible: yes

question: What is the purpose of the forth rail?
is_impossible: yes

question: Where is third rail situated in the street trams system?
is_impossible: yes
context: The first attempts to use standard-frequency single-phase AC were made in Hungary as far back as 1923, by the Hungarian Kálmán Kandó on the line between Budapest-Nyugati and Alag, using 16 kV at 50 Hz. The locomotives carried a four-pole rotating phase converter feeding a single traction motor of the polyphase induction type at 600 to 1,100 V. The number of poles on the 2,500 hp motor could be changed using slip rings to run at one of four synchronous speeds. The tests were a success so, from 1932 until the 1960s, trains on the Budapest-Hegyeshalom line (towards Vienna) regularly used the same system. A few decades after the Second World War, the 16 kV was changed to the Russian and later French 25 kV system.

qas: question: What was the main requirement for electric feeder stations?
answers: text: line fed from different feeder stations must be kept strictly isolated
is_impossible: no

question: What invention prevented lines from getting mixed?
answers: text: Phase Breaks
is_impossible: no

question: What was the part of wire in Phase Break sections an arc being drawn from one wire to another?
answers: text: The earthed section
is_impossible: no

question: How were the drivers warned to start coasting the train?
answers: text: warning board
is_impossible: no

question: What should the driver do in order to open and close the circuit breaker?
answers: text: to shut off power and coast
is_impossible: no

question: Charged Sections consist of an earthed section of what?
is_impossible: yes

question: In the US, a system known as Automatic Power Control does what?
is_impossible: yes

question: Typically what are in use all the time?
is_impossible: yes

question: The earthed section allows for what?
is_impossible: yes

question: What must not be coasting to prevent the risk of an arc being drawn?
is_impossible: yes

question: Where was the system similar to London Underground used as well?
is_impossible: yes

question: What is of the factors the capital cost of electrification system depends on?
is_impossible: yes

question: Which type of supply for electric motors creates electromagnetic radiation?
is_impossible: yes
context: To prevent the risk of out-of-phase supplies mixing, sections of line fed from different feeder stations must be kept strictly isolated. This is achieved by Neutral Sections (also known as Phase Breaks), usually provided at feeder stations and midway between them although, typically, only half are in use at any time, the others being provided to allow a feeder station to be shut down and power provided from adjacent feeder stations. Neutral Sections usually consist of an earthed section of wire which is separated from the live wires on either side by insulating material, typically ceramic beads, designed so that the pantograph will smoothly run from one section to the other. The earthed section prevents an arc being drawn from one live section to the other, as the voltage difference may be higher than the normal system voltage if the live sections are on different phases and the protective circuit breakers may not be able to safely interrupt the considerable current that would flow. To prevent the risk of an arc being drawn across from one section of wire to earth, when passing through the neutral section, the train must be coasting and the circuit breakers must be open. In many cases, this is done manually by the drivers. To help them, a warning board is provided just before both the neutral section and an advance warning some distance before. A further board is then provided after the neutral section to tell drivers to re-close the circuit breaker, although drivers must not do this until the rear pantograph has passed this board. In the UK, a system known as Automatic Power Control (APC) automatically opens and closes the circuit breaker, this being achieved by using sets of permanent magnets alongside the track communicating with a detector on the train. The only action needed by the driver is to shut off power and coast and therefore warning boards are still provided at and on the approach to neutral sections.

qas: question: What nowdays electrification systems can use?
answers: text: DC motors which directly use the DC or they may be 3-phase AC motors
is_impossible: no

question: What is the main action AC and DC systems have to deal with?
answers: text: converting and transporting
is_impossible: no

question: What type of losses happen during conversion and transmission in wires and electronics?
answers: text: ohmic losses
is_impossible: no

question: What kind of losses take place in transformers and inductors during conversion/transmission process?
answers: text: magnetic field losses
is_impossible: no

question: Modern electrification systems take DC energy from what?
is_impossible: yes

question: 4-phase AC motors require further what?
is_impossible: yes

question: What doesn't involve losses?
is_impossible: yes

question: Power conversion for an AC system takes place mainly in a what?
is_impossible: yes

question: The energy used to blow air to heat transformers must be what?
is_impossible: yes

question: What was rewired to the standard four-rail system?
is_impossible: yes

question: How can electric train be more energy efficient?
is_impossible: yes

question: What insures minimal current leak during power rails instalation?
is_impossible: yes
context: Modern electrification systems take AC energy from a power grid which is delivered to a locomotive and converted to a DC voltage to be used by traction motors. These motors may either be DC motors which directly use the DC or they may be 3-phase AC motors which require further conversion of the DC to 3-phase AC (using power electronics). Thus both systems are faced with the same task: converting and transporting high-voltage AC from the power grid to low-voltage DC in the locomotive. Where should this conversion take place and at what voltage and current (AC or DC) should the power flow to the locomotive? And how does all this relate to energy-efficiency? Both the transmission and conversion of electric energy involve losses: ohmic losses in wires and power electronics, magnetic field losses in transformers and smoothing reactors (inductors). Power conversion for a DC system takes place mainly in a railway substation where large, heavy, and more efficient hardware can be used as compared to an AC system where conversion takes place aboard the locomotive 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.

qas: question: What two systems were compare in the Soviet Union in 1970?
answers: text: 3 kV DC and 25 kV AC (50 Hz
is_impossible: no

question: Which system had higher losses in overhead wires?
answers: text: 3 kV DC
is_impossible: no

question: Which system was used in Soviet Union after all calculations?
answers: text: 3 kV DC
is_impossible: no

question: What came with lesser lesser cost mobile conversion hardware or stationary hardware?
answers: text: stationary hardware
is_impossible: no

question: It takes energy to move mobile conversion software where?
is_impossible: yes

question: Which hardware in the railway substation incurs energy costs?
is_impossible: yes

question: What was less energy efficient in than AC in providing energy?
is_impossible: yes

question: The conversion for what system took place in the railway station?
is_impossible: yes

question: Most of the conversion for the DC program took place inside what?
is_impossible: yes

question: The circuit is left undivided in what system?
is_impossible: yes

question: What locomotives are usually more reliable?
is_impossible: yes

question: What line used the overhead wire system first Victoria to Crystal Palace or Peckham Rye to West Noorwood?
is_impossible: yes
context: In the Soviet Union, in the 1970s, a comparison was made between systems electrified at 3 kV DC and 25 kV AC (50 Hz). The results showed that percentage losses in the overhead wires (catenary and contact wires) was over 3 times greater for 3 kV DC than for 25 kV AC. But when the conversion losses were all taken into account and added to overhead wire losses (including cooling blower energy) the 25 kV AC lost a somewhat higher percent of energy than for 3 kV DC. Thus in spite of the much higher losses in the catenary, the 3 kV DC was a little more energy efficient than AC in providing energy from the USSR power grid to the terminals of the traction motors (all DC at that time). While both systems use energy in converting higher voltage AC from the USSR's power grid to lower voltage DC, the conversions for the DC system all took place (at higher efficiency) in the railway substation, while most of the conversion for the AC system took place inside the locomotive (at lower efficiency). Consider also that it takes energy to constantly move this mobile conversion hardware over the rails while the stationary hardware in the railway substation doesn't incur this energy cost. For more details see: Wiki: Soviet Union DC vs. AC.

qas: question: What can be seen in the newly electrified lines?
answers: text: "sparks effect"
is_impossible: no

question: What can electrification of modern trains effect? 
answers: text: patronage / revenue
is_impossible: no

question: How can better service quality be achieved?
answers: text: rolling stock overhaul / replacement
is_impossible: no

question: Electrification in passenger rail systems leads to insignificant jumps in what?
is_impossible: yes

question: What leads to decreasing service quality?
is_impossible: yes

question: A "sparks effect" is often seen on old lines which are what?
is_impossible: yes

question: Electric trains are often seen as less modern and what?
is_impossible: yes

question: What is well established for routes that have been electrified for days?
is_impossible: yes

question: Is "low" voltage used by trains safe for people?
is_impossible: yes

question: A brush-type BC motor operated at what speeds?
is_impossible: yes

question: What came with lesser lesser cost mobile conversion hardware or stationary hardware?
is_impossible: yes
context: Newly electrified lines often show a "sparks effect", whereby electrification in passenger rail systems leads to significant jumps in patronage / revenue. The reasons may include electric trains being seen as more modern and attractive to ride, faster and smoother service, and the fact that electrification often goes hand in hand with a general infrastructure and rolling stock overhaul / replacement, which leads to better service quality (in a way that theoretically could also be achieved by doing similar upgrades yet without electrification). Whatever the causes of the sparks effect, it is well established for numerous routes that have electrified over decades.

qas: question: What is a major factor whn it comes to electrification?
answers: text: Network effects
is_impossible: no

question: What was the reason some electrifications were removed after a while?
answers: text: through traffic to non-electrified lines
is_impossible: no

question: Where can the issue of through traffic benefits occur?
answers: text: long distance trips
is_impossible: no

question: What can be a drawback of electrification of long distance freight trains?
answers: text: electrification to isolated areas
is_impossible: no

question: What does the increasing demand for container traffic make companies use more often?
answers: text: diesel trains
is_impossible: no

question: What is a small factor with electrification?
is_impossible: yes

question: What must be considered when converting lines from electric?
is_impossible: yes

question: What has been removed because of the through traffic to electrified lines?
is_impossible: yes

question: What is mostly an issue for short distance trips?
is_impossible: yes

question: Companies often find they need to use what trains to heavily populated areas?
is_impossible: yes

question: What depth does the alternating current penetrate in a steel rail?
is_impossible: yes

question: All early electrified motors used what type of motor?
is_impossible: yes

question: What is the other name for the street trams?
is_impossible: yes
context: Network effects are a large factor with electrification. When converting lines to electric, the connections with other lines must be considered. Some electrifications have subsequently been removed because of the through traffic to non-electrified lines. If through traffic is to have any benefit, time consuming engine switches must occur to make such connections or expensive dual mode engines must be used. This is mostly an issue for long distance trips, but many lines come to be dominated by through traffic from long-haul freight trains (usually running coal, ore, or containers to or from ports). In theory, these trains could enjoy dramatic savings through electrification, but it can be too costly to extend electrification to isolated areas, and unless an entire network is electrified, companies often find that they need to continue use of diesel trains even if sections are electrified. The increasing demand for container traffic which is more efficient when utilizing the double-stack car also has network effect issues with existing electrifications due to insufficient clearance of overhead electrical lines for these trains, but electrification can be built or modified to have sufficient clearance, at additional cost.

qas: question: What is the other issue that comes to sight when using electrification system?
answers: text: connections between different electrical services
is_impossible: no

question: Why the commuter lines built to different standards can cause be complicated?
answers: text: the implications on the sections it is connecting
is_impossible: no

question: What is the solution many lines came up with in order to avoid replacing present rolling stock?
answers: text: to be overlaid with multiple electrification standards
is_impossible: no

question: Why are disel trains  still used on electrified routes?
answers: text: due to incompatibility of electrification standards
is_impossible: no

question: What can be very inexpensive?
is_impossible: yes

question: What is often built to the same standards?
is_impossible: yes

question: What trains run along partially electrified routes?
is_impossible: yes

question: What is compatible along the route?
is_impossible: yes

question: How many lines have come to be overlaid with single electrification standards?
is_impossible: yes

question: How many narrow-gauge lines in Slovakia?
is_impossible: yes

question: What can electromagnetic radiation interfere with?
is_impossible: yes

question: What can often be generated with a lower efficiency?
is_impossible: yes
context: Additionally, there are issues of connections between different electrical services, particularly connecting intercity lines with sections electrified for commuter traffic, but also between commuter lines built to different standards. This can cause electrification of certain connections to be very expensive simply because of the implications on the sections it is connecting. Many lines have come to be overlaid with multiple electrification standards for different trains to avoid having to replace the existing rolling stock on those lines. Obviously, this requires that the economics of a particular connection must be more compelling and this has prevented complete electrification of many lines. In a few cases, there are diesel trains running along completely electrified routes and this can be due to incompatibility of electrification standards along the route.

qas: question: Which of two can be more efficiently electricified?
answers: text: Central station
is_impossible: no

question: How can electric power plant become more power efficient?
answers: text: it will shut down its least efficient generators
is_impossible: no

question: How can electric train be more energy efficient?
answers: text: by regenerative braking
is_impossible: no

question: Which type of train continues to use energy while coasting or being stopped?
answers: text: diesel
is_impossible: no

question: What causes electric trains to waste energy?
answers: text: cooling blowers
is_impossible: no

question: Diesel motors increase in efficiency where?
is_impossible: yes

question: Electric rolling stock may use heating blowers when?
is_impossible: yes

question: What can often be generated with a lower efficiency?
is_impossible: yes

question: If an electric power plant needs to generate more power it shuts down what?
is_impossible: yes

question: The diesel train can save energy by regenerative what?
is_impossible: yes

question: The first four-way lines were created in what year?
is_impossible: yes

question: What was formally used by the Mississippi Road?
is_impossible: yes

question: What is more prefferable for subway lines?
is_impossible: yes
context: Central station electricity can often be generated with higher efficiency than a mobile engine/generator. While the efficiency of power plant generation and diesel locomotive generation are roughly the same in the nominal regime, diesel motors decrease in efficiency in non-nominal regimes at low power  while if an electric power plant needs to generate less power it will shut down its least efficient generators, thereby increasing efficiency. The electric train can save energy (as compared to diesel) by regenerative braking and by not needing to consume energy by idling as diesel locomotives do when stopped or coasting. However, electric rolling stock may run cooling blowers when stopped or coasting, thus consuming energy.

qas: question: Can renewable source of electricity be used in mobile power plants?
answers: text: unsuitable
is_impossible: no

question: What type of natural resources is more scarce?
answers: text: liquid fuel
is_impossible: no

question: What is the recent incentive in  order to overcome oil scarcity?
answers: text: to substitute other fuels
is_impossible: no

question: What research can be used in the future if translated?
answers: text: Soviet studies from the 1980s
is_impossible: no

question: Energy sources suitable for mobile power plants include what?
is_impossible: yes

question: The reserves of nuclear fuel are what?
is_impossible: yes

question: Most countries with small rail networks do not have what?
is_impossible: yes

question: What is considered an insignificant route towards consumption pattern reform?
is_impossible: yes

question: Translated Soviet studies are available from what decade?
is_impossible: yes

question: What depth does the alternating current penetrate in a steel rail?
is_impossible: yes

question: How did non-standard gauge trains start to operate with high-voltage AC?
is_impossible: yes

question: What runs on a pair of wide roadways made of steel?
is_impossible: yes
context: Energy sources unsuitable for mobile power plants, such as nuclear power, renewable hydroelectricity, or wind power can be used. According to widely accepted global energy reserve statistics, the reserves of liquid fuel are much less than gas and coal (at 42, 167 and 416 years respectively). Most countries with large rail networks do not have significant oil reserves and those that did, like the United States and Britain, have exhausted much of their reserves and have suffered declining oil output for decades. Therefore, there is also a strong economic incentive to substitute other fuels for oil. Rail electrification is often considered an important route towards consumption pattern reform. However, there are no reliable, peer-reviewed studies available to assist in rational public debate on this critical issue, although there are untranslated Soviet studies from the 1980s.

qas: question: What type of trains became more energy-efficient in the former Soviet Union?
answers: text: electric
is_impossible: no

question: What year could be marked as year when electric railways more efficient than diesel ones?
answers: text: 1965
is_impossible: no

question: How much fuel did electric train used less than diesel in the middle of 1970 in USSR?
answers: text: 25% less fuel per ton-km
is_impossible: no

question: What could be a factor of lower energy consumption for electric trains?
answers: text: better operating conditions on electrified lines
is_impossible: no

question: How much more expensive was diesel compare to electricity per unit?
answers: text: 1.5 times more (per unit of heat energy content
is_impossible: no

question: In the US, electric traction became more energy-efficient than what?
is_impossible: yes

question: When was diesel traction three times as efficient as electric traction?
is_impossible: yes

question: In what decade did electrics use about 35% less fuel per ton-km.
is_impossible: yes

question: The cost of diesel was 2.5 times more than what? 
is_impossible: yes

question: Due to the inefficient generation of electricity in the US, diesel traction was twice as energy efficient in what year?
is_impossible: yes

question: All regions use the same supply voltages and?
is_impossible: yes

question: What must operate at constant speeds?
is_impossible: yes

question: 4-phase AC motors require further what?
is_impossible: yes
context: In the former Soviet Union, electric traction eventually became somewhat more energy-efficient than diesel. Partly due to inefficient generation of electricity in the USSR (only 20.8% thermal efficiency in 1950 vs. 36.2% in 1975), in 1950 diesel traction was about twice as energy efficient as electric traction (in terms of net tonne-km of freight per kg of fuel). But as efficiency of electricity generation (and thus of electric traction) improved, by about 1965 electric railways became more efficient than diesel. After the mid 1970s electrics used about 25% less fuel per ton-km. However diesels were mainly used on single track lines with a fair amount of traffic  so that the lower fuel consumption of electrics may be in part due to better operating conditions on electrified lines (such as double tracking) rather than inherent energy efficiency. Nevertheless, the cost of diesel fuel was about 1.5 times more (per unit of heat energy content) than that of the fuel used in electric power plants (that generated electricity), thus making electric railways even more energy-cost effective.

qas: question: What caused the energy efficiency to go up?
answers: text: energy-intensity dropping
is_impossible: no

question: Elimination of what helped the efficiency of diesel traction to go up?
answers: text: 2-axle freight cars
is_impossible: no

question: What type of locomotives got improved during 1950-1973 in Soviet Union?
answers: text: electric
is_impossible: no

question: How much of energy was saved and re-used due to regenerative braking in 1989?
answers: text: 2.65%
is_impossible: no

question: Was there an energy efficiency improvement in the period 1974 through 1980?
answers: text: no improvement
is_impossible: no

question: There was a decreased use of what type of braking?
is_impossible: yes

question: The overall efficiency of electric traction tripled during what years?
is_impossible: yes

question: The overall efficiency of electric traction tripled in what country?
is_impossible: yes

question: There were massive improvements in energy-intensity after what year?
is_impossible: yes

question: Energy-efficiency increases as what goes up?
is_impossible: yes

question: What is a major factor whn it comes to electrification?
is_impossible: yes

question: Because of the Second World War, what was not completed?
is_impossible: yes

question: In what decade did electrics use about 35% less fuel per ton-km.
is_impossible: yes
context: Besides increased efficiency of power plants, there was an increase in efficiency (between 1950 and 1973) of the railway utilization of this electricity with energy-intensity dropping from 218 to 124 kwh/10,000 gross tonne-km (of both passenger and freight trains) or a 43% drop. Since energy-intensity is the inverse of energy-efficiency it drops as efficiency goes up. But most of this 43% decrease in energy-intensity also benefited diesel traction. The conversion of wheel bearings from plain to roller, increase of train weight, converting single track lines to double track (or partially double track), and the elimination of obsolete 2-axle freight cars increased the energy-efficiency of all types of traction: electric, diesel, and steam. However, there remained a 12–15% reduction of energy-intensity that only benefited electric traction (and not diesel). This was due to improvements in locomotives, more widespread use of regenerative braking (which in 1989 recycled 2.65% of the electric energy used for traction,) remote control of substations, better handling of the locomotive by the locomotive crew, and improvements in automation. Thus the overall efficiency of electric traction as compared to diesel more than doubled between 1950 and the mid-1970s in the Soviet Union. But after 1974 (thru 1980) there was no improvement in energy-intensity (wh/tonne-km) in part due to increasing speeds of passenger and freight trains.