praj-17/QA-MCQ-Open-ended huggingface dataset:
Title: Railway_electrification_system
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.

question: How can DC motor turn universal? 

answer: if fitted with laminated pole pieces

question: What problems did AC distribution cause? 

answer: inductive reactance and eddy current losses

question: How do railways try to solve the problem of inductive reactance of AC system? 

answer: low AC frequencies

question: How can low frequencies be obtained? 

answer: converted from utility power
Title: Railway_electrification_system
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.

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

answer: adopting the already proven RhB system.

question: When was the first trail of RhB system tested? 

answer: 1913
Title: Railway_electrification_system
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.

question: What frequency was typically used on US Amtrak? 

answer: 25 Hz

question: What voltage does SEPTA system use? 

answer: 12 kV voltage

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

answer: catenary voltage

question: When was a 11kV system of NY, New Haven and Hartford was converted to 12.5 kV? 

answer: 1987
Title: Railway_electrification_system
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.

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

answer: 1 December 1909

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

answer: Victoria to Crystal Palace

question: What was the cause of lines not being extended? 

answer: the First World War

question: What voltage was used in the two lines opened in 1925 of Southern Railway? 

answer: 6.7 kV 25 Hz
Title: Railway_electrification_system
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.

question: What countries  used three-phase AC system in the the beginning of 20th century? 

answer: Italy, Switzerland and the United States

question: What country was a bigger user compare to the three of them? 

answer: Italy

question: Where did Italy start using the AC system? 

answer: in the mountainous regions of northern Italy

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

answer: 1901 until 1976

question: How long did three-phase system operate in Cascade Tunnel? 

answer: 1909 to 1927
Title: Railway_electrification_system
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.

question: What country has first tried to use single-phase AC? 

answer: Hungary

question: What frequency did the line of Hungarian rail system used in 1923? 

answer: 16 kV at 50 Hz

question: What type of the converter was used in hungarian locomotives of that time? 

answer: four-pole rotating phase converter

question: How could the locomotives run on four speed levels? 

answer: motor could be changed using slip rings

question: What system was adopted in Hungary after WWII? 

answer: Russian
Title: Railway_electrification_system
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.

question: What was the main requirement for electric feeder stations? 

answer: line fed from different feeder stations must be kept strictly isolated

question: What invention prevented lines from getting mixed? 

answer: Phase Breaks

question: What was the part of wire in Phase Break sections an arc being drawn from one wire to another? 

answer: The earthed section

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

answer: warning board

question: What should the driver do in order to open and close the circuit breaker? 

answer: to shut off power and coast
Title: Railway_electrification_system
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.

question: What nowdays electrification systems can use? 

answer: DC motors which directly use the DC or they may be 3-phase AC motors

question: What is the main action AC and DC systems have to deal with? 

answer: converting and transporting

question: What type of losses happen during conversion and transmission in wires and electronics? 

answer: ohmic losses

question: What kind of losses take place in transformers and inductors during conversion/transmission process? 

answer: magnetic field losses
Title: Railway_electrification_system
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.

question: What two systems were compare in the Soviet Union in 1970? 

answer: 3 kV DC and 25 kV AC (50 Hz

question: Which system had higher losses in overhead wires? 

answer: 3 kV DC

question: Which system was used in Soviet Union after all calculations? 

answer: 3 kV DC

question: What came with lesser lesser cost mobile conversion hardware or stationary hardware? 

answer: stationary hardware
Title: Railway_electrification_system
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.

question: What can be seen in the newly electrified lines? 

answer: "sparks effect"

question: What can electrification of modern trains effect?  

answer: patronage / revenue

question: How can better service quality be achieved? 

answer: rolling stock overhaul / replacement
Title: Railway_electrification_system
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.

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

answer: Network effects

question: What was the reason some electrifications were removed after a while? 

answer: through traffic to non-electrified lines

question: What can be a drawback of electrification of long distance freight trains? 

answer: electrification to isolated areas

question: Where can the issue of through traffic benefits occur? 

answer: long distance trips

question: What does the increasing demand for container traffic make companies use more often? 

answer: diesel trains
Title: Railway_electrification_system
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.

question: What is the other issue that comes to sight when using electrification system? 

answer: connections between different electrical services

question: Why the commuter lines built to different standards can cause be complicated? 

answer: the implications on the sections it is connecting

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

answer: to be overlaid with multiple electrification standards

question: Why are disel trains  still used on electrified routes? 

answer: due to incompatibility of electrification standards
Title: Railway_electrification_system
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.

question: Which of two can be more efficiently electricified? 

answer: Central station

question: How can electric power plant become more power efficient? 

answer: it will shut down its least efficient generators

question: How can electric train be more energy efficient? 

answer: by regenerative braking

question: Which type of train continues to use energy while coasting or being stopped? 

answer: diesel

question: What causes electric trains to waste energy? 

answer: cooling blowers
Title: Railway_electrification_system
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.

question: Can renewable source of electricity be used in mobile power plants? 

answer: unsuitable

question: What is the recent incentive in  order to overcome oil scarcity? 

answer: to substitute other fuels

question: What type of natural resources is more scarce? 

answer: liquid fuel

question: What research can be used in the future if translated? 

answer: Soviet studies from the 1980s
Title: Railway_electrification_system
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.

question: What type of trains became more energy-efficient in the former Soviet Union? 

answer: electric

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

answer: 1965

question: How much fuel did electric train used less than diesel in the middle of 1970 in USSR? 

answer: 25% less fuel per ton-km

question: What could be a factor of lower energy consumption for electric trains? 

answer: better operating conditions on electrified lines

question: How much more expensive was diesel compare to electricity per unit? 

answer: 1.5 times more (per unit of heat energy content
Title: Railway_electrification_system
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.

question: What caused the energy efficiency to go up? 

answer: energy-intensity dropping

question: What type of locomotives got improved during 1950-1973 in Soviet Union? 

answer: electric

question: How much of energy was saved and re-used due to regenerative braking in 1989? 

answer: 2.65%

question: Was there an energy efficiency improvement in the period 1974 through 1980? 

answer: no improvement

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

answer: 2-axle freight cars