Split (3)

train · 87.6k rows

id stringlengths 24 24	title stringclasses 442 values	context stringlengths 151 3.71k	question stringlengths 12 270	answers dict
572f3f3404bcaa1900d767c8	Railway_electrification_system	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 ...	Does energized segment of third rail pose the threat to pedestrians if uncovered?	{ "answer_start": [ 700 ], "text": [ "no danger" ] }
572f40f1b2c2fd1400567f9f	Railway_electrification_system	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 ...	What type of system does London Underground use?	{ "answer_start": [ 73 ], "text": [ "four-rail system" ] }
572f40f1b2c2fd1400567fa0	Railway_electrification_system	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 ...	What is the purpose of the forth rail?	{ "answer_start": [ 111 ], "text": [ "carries the electrical return" ] }
572f40f1b2c2fd1400567fa1	Railway_electrification_system	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 ...	What is the volatage surge of the third rail of London Underground system?	{ "answer_start": [ 304 ], "text": [ "+420v DC" ] }
572f40f1b2c2fd1400567fa2	Railway_electrification_system	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 ...	What is the voltage of the return rail?	{ "answer_start": [ 394 ], "text": [ "−210v DC" ] }
572f40f1b2c2fd1400567fa3	Railway_electrification_system	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 ...	Where was the system similar to London Underground used as well?	{ "answer_start": [ 772 ], "text": [ "Milan" ] }
572f42c2947a6a140053c81f	Railway_electrification_system	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 a...	What danger can return currents cause?	{ "answer_start": [ 290 ], "text": [ "electrolytic damage" ] }
572f42c2947a6a140053c821	Railway_electrification_system	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 a...	How are stray earth currents kept to a manageable levels?	{ "answer_start": [ 848 ], "text": [ "by using resistors" ] }
572f42c2947a6a140053c822	Railway_electrification_system	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 a...	What insures minimal current leak during power rails instalation?	{ "answer_start": [ 993 ], "text": [ "ceramic chairs" ] }
572f42c2947a6a140053c820	Railway_electrification_system	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 a...	How did return current effect water and gas in iron pipes?	{ "answer_start": [ 508 ], "text": [ "water and gas mains" ] }
572f42c2947a6a140053c81e	Railway_electrification_system	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 a...	What is the crucial advantage of four-rail system?	{ "answer_start": [ 58 ], "text": [ "running rail carries any current" ] }
572f447f947a6a140053c845	Railway_electrification_system	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 sp...	Why some sections of Bakerloo and District lines were rewired to three-rail system?	{ "answer_start": [ 568 ], "text": [ "to simplify rolling stock use" ] }
572f447f947a6a140053c844	Railway_electrification_system	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 sp...	What is the voltage shared two types of trains UK railroad system?	{ "answer_start": [ 254 ], "text": [ "660 V" ] }
572f447f947a6a140053c846	Railway_electrification_system	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 sp...	How did it become possible to share the voltage for different types of train?	{ "answer_start": [ 135 ], "text": [ "the centre rail is connected to the running rails" ] }
572f4794b2c2fd1400567fc7	Railway_electrification_system	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 co...	Why some lines of Paris Metro have to operate on a four-rail system?	{ "answer_start": [ 97 ], "text": [ "rubber tyres" ] }
572f4794b2c2fd1400567fc8	Railway_electrification_system	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 co...	What was the solution for the return current problem in Paris Metro?	{ "answer_start": [ 249 ], "text": [ "two guide rails" ] }
572f4794b2c2fd1400567fc9	Railway_electrification_system	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 co...	What is required in order for the guide rails to operate properly?	{ "answer_start": [ 491 ], "text": [ "a single polarity supply" ] }
572f4794b2c2fd1400567fca	Railway_electrification_system	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 co...	How train is able to turn around after each completed journey?	{ "answer_start": [ 619 ], "text": [ "reversing loops" ] }
572f4794b2c2fd1400567fcb	Railway_electrification_system	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 co...	Why was the reversing loop created?	{ "answer_start": [ 783 ], "text": [ "having to 'run around' the rest of the train" ] }
572f498104bcaa1900d76818	Railway_electrification_system	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,...	How can different range of voltages be supplied for AC locomotives?	{ "answer_start": [ 139 ], "text": [ "multiple taps on the transformer" ] }
572f498104bcaa1900d76817	Railway_electrification_system	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,...	What was a disadvantage of DC system?	{ "answer_start": [ 37 ], "text": [ "power-wasting resistors" ] }
572f498104bcaa1900d76819	Railway_electrification_system	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,...	What taps can provide lighting supply?	{ "answer_start": [ 213 ], "text": [ "low-voltage transformer windings" ] }
572f498104bcaa1900d7681a	Railway_electrification_system	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,...	What will AC/DC motor be replaced with?	{ "answer_start": [ 450 ], "text": [ "three-phase induction motor" ] }
572f498104bcaa1900d7681b	Railway_electrification_system	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,...	What is the main advantage of an induction motor?	{ "answer_start": [ 608 ], "text": [ "can run equally well on DC or AC of any frequency" ] }
572f4ab9b2c2fd1400567fef	Railway_electrification_system	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 ...	How can DC motor turn universal?	{ "answer_start": [ 32 ], "text": [ "if fitted with laminated pole pieces" ] }
572f4ab9b2c2fd1400567ff0	Railway_electrification_system	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 ...	What problems did AC distribution cause?	{ "answer_start": [ 296 ], "text": [ "inductive reactance and eddy current losses" ] }
572f4ab9b2c2fd1400567ff1	Railway_electrification_system	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 ...	How do railways try to solve the problem of inductive reactance of AC system?	{ "answer_start": [ 361 ], "text": [ "low AC frequencies" ] }
572f4ab9b2c2fd1400567ff2	Railway_electrification_system	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 ...	How can low frequencies be obtained?	{ "answer_start": [ 421 ], "text": [ "converted from utility power" ] }
572f4cdaa23a5019007fc501	Railway_electrification_system	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 Rh...	How did non-standard gauge trains start to operate with high-voltage AC?	{ "answer_start": [ 556 ], "text": [ "adopting the already proven RhB system." ] }
572f4cdaa23a5019007fc502	Railway_electrification_system	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 Rh...	When was the first trail of RhB system tested?	{ "answer_start": [ 360 ], "text": [ "1913" ] }
572f4ec3a23a5019007fc505	Railway_electrification_system	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...	What frequency was typically used on US Amtrak?	{ "answer_start": [ 22 ], "text": [ "25 Hz" ] }
572f4ec3a23a5019007fc506	Railway_electrification_system	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...	What voltage does SEPTA system use?	{ "answer_start": [ 326 ], "text": [ "12 kV voltage" ] }
572f4ec3a23a5019007fc507	Railway_electrification_system	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...	What specification is similar for both Amtrak and Septa systems?	{ "answer_start": [ 496 ], "text": [ "catenary voltage" ] }
572f4ec3a23a5019007fc508	Railway_electrification_system	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...	When was a 11kV system of NY, New Haven and Hartford was converted to 12.5 kV?	{ "answer_start": [ 1065 ], "text": [ "1987" ] }
572f506a04bcaa1900d76841	Railway_electrification_system	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. Fu...	When was overhead wires system being used for the first time in UK?	{ "answer_start": [ 177 ], "text": [ "1 December 1909" ] }
572f506a04bcaa1900d76842	Railway_electrification_system	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. Fu...	What line used the overhead wire system first Victoria to Crystal Palace or Peckham Rye to West Noorwood?	{ "answer_start": [ 194 ], "text": [ "Victoria to Crystal Palace" ] }
572f506a04bcaa1900d76843	Railway_electrification_system	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. Fu...	What was the cause of lines not being extended?	{ "answer_start": [ 360 ], "text": [ "the First World War" ] }
572f506a04bcaa1900d76844	Railway_electrification_system	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. Fu...	What voltage was used in the two lines opened in 1925 of Southern Railway?	{ "answer_start": [ 514 ], "text": [ "6.7 kV 25 Hz" ] }
572f52bc04bcaa1900d76849	Railway_electrification_system	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 Ferro...	What countries used three-phase AC system in the the beginning of 20th century?	{ "answer_start": [ 51 ], "text": [ "Italy, Switzerland and the United States" ] }
572f52bc04bcaa1900d7684a	Railway_electrification_system	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 Ferro...	What country was a bigger user compare to the three of them?	{ "answer_start": [ 124 ], "text": [ "Italy" ] }
572f52bc04bcaa1900d7684b	Railway_electrification_system	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 Ferro...	Where did Italy start using the AC system?	{ "answer_start": [ 160 ], "text": [ "in the mountainous regions of northern Italy" ] }
572f52bc04bcaa1900d7684c	Railway_electrification_system	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 Ferro...	How long did the AC system last in northern Italy?	{ "answer_start": [ 210 ], "text": [ "1901 until 1976" ] }
572f52bc04bcaa1900d7684d	Railway_electrification_system	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 Ferro...	How long did three-phase system operate in Cascade Tunnel?	{ "answer_start": [ 615 ], "text": [ "1909 to 1927" ] }
572f54f7b2c2fd140056802b	Railway_electrification_system	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 inductio...	What country has first tried to use single-phase AC?	{ "answer_start": [ 74 ], "text": [ "Hungary" ] }
572f54f7b2c2fd140056802c	Railway_electrification_system	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 inductio...	What frequency did the line of Hungarian rail system used in 1923?	{ "answer_start": [ 186 ], "text": [ "16 kV at 50 Hz" ] }
572f54f7b2c2fd140056802d	Railway_electrification_system	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 inductio...	What type of the converter was used in hungarian locomotives of that time?	{ "answer_start": [ 228 ], "text": [ "four-pole rotating phase converter" ] }
572f54f7b2c2fd140056802e	Railway_electrification_system	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 inductio...	How could the locomotives run on four speed levels?	{ "answer_start": [ 382 ], "text": [ "motor could be changed using slip rings" ] }
572f54f7b2c2fd140056802f	Railway_electrification_system	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 inductio...	What system was adopted in Hungary after WWII?	{ "answer_start": [ 680 ], "text": [ "Russian" ] }
572f575504bcaa1900d76863	Railway_electrification_system	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, t...	What was the main requirement for electric feeder stations?	{ "answer_start": [ 65 ], "text": [ "line fed from different feeder stations must be kept strictly isolated" ] }
572f575504bcaa1900d76864	Railway_electrification_system	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, t...	What invention prevented lines from getting mixed?	{ "answer_start": [ 189 ], "text": [ "Phase Breaks" ] }
572f575504bcaa1900d76865	Railway_electrification_system	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, t...	What was the part of wire in Phase Break sections an arc being drawn from one wire to another?	{ "answer_start": [ 684 ], "text": [ "The earthed section" ] }
572f575504bcaa1900d76866	Railway_electrification_system	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, t...	How were the drivers warned to start coasting the train?	{ "answer_start": [ 1259 ], "text": [ "warning board" ] }
572f575504bcaa1900d76867	Railway_electrification_system	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, t...	What should the driver do in order to open and close the circuit breaker?	{ "answer_start": [ 1828 ], "text": [ "to shut off power and coast" ] }
572f591404bcaa1900d76889	Railway_electrification_system	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 ...	What nowdays electrification systems can use?	{ "answer_start": [ 187 ], "text": [ "DC motors which directly use the DC or they may be 3-phase AC motors" ] }
572f591404bcaa1900d7688a	Railway_electrification_system	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 ...	What is the main action AC and DC systems have to deal with?	{ "answer_start": [ 388 ], "text": [ "converting and transporting" ] }
572f591404bcaa1900d7688b	Railway_electrification_system	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 ...	What type of losses happen during conversion and transmission in wires and electronics?	{ "answer_start": [ 736 ], "text": [ "ohmic losses" ] }
572f591404bcaa1900d7688c	Railway_electrification_system	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 ...	What kind of losses take place in transformers and inductors during conversion/transmission process?	{ "answer_start": [ 781 ], "text": [ "magnetic field losses" ] }
572f5a7c947a6a140053c8ac	Railway_electrification_system	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 ac...	What two systems were compare in the Soviet Union in 1970?	{ "answer_start": [ 88 ], "text": [ "3 kV DC and 25 kV AC (50 Hz" ] }
572f5a7c947a6a140053c8ad	Railway_electrification_system	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 ac...	Which system had higher losses in overhead wires?	{ "answer_start": [ 240 ], "text": [ "3 kV DC" ] }
572f5a7c947a6a140053c8ae	Railway_electrification_system	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 ac...	Which system was used in Soviet Union after all calculations?	{ "answer_start": [ 457 ], "text": [ "3 kV DC" ] }
572f5a7c947a6a140053c8af	Railway_electrification_system	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 ac...	What came with lesser lesser cost mobile conversion hardware or stationary hardware?	{ "answer_start": [ 1109 ], "text": [ "stationary hardware" ] }
572f5bb3b2c2fd140056807b	Railway_electrification_system	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 h...	What can be seen in the newly electrified lines?	{ "answer_start": [ 37 ], "text": [ "\"sparks effect\"" ] }
572f5bb3b2c2fd140056807c	Railway_electrification_system	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 h...	What can electrification of modern trains effect?	{ "answer_start": [ 134 ], "text": [ "patronage / revenue" ] }
572f5bb3b2c2fd140056807d	Railway_electrification_system	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 h...	How can better service quality be achieved?	{ "answer_start": [ 366 ], "text": [ "rolling stock overhaul / replacement" ] }
572f618b04bcaa1900d768a3	Railway_electrification_system	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 ...	What is a major factor whn it comes to electrification?	{ "answer_start": [ 0 ], "text": [ "Network effects" ] }
572f618b04bcaa1900d768a4	Railway_electrification_system	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 ...	What was the reason some electrifications were removed after a while?	{ "answer_start": [ 213 ], "text": [ "through traffic to non-electrified lines" ] }
572f618b04bcaa1900d768a6	Railway_electrification_system	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 ...	What can be a drawback of electrification of long distance freight trains?	{ "answer_start": [ 718 ], "text": [ "electrification to isolated areas" ] }
572f618b04bcaa1900d768a5	Railway_electrification_system	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 ...	Where can the issue of through traffic benefits occur?	{ "answer_start": [ 438 ], "text": [ "long distance trips" ] }
572f618b04bcaa1900d768a7	Railway_electrification_system	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 ...	What does the increasing demand for container traffic make companies use more often?	{ "answer_start": [ 853 ], "text": [ "diesel trains" ] }
572f63e6b2c2fd14005680a7	Railway_electrification_system	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 bec...	What is the other issue that comes to sight when using electrification system?	{ "answer_start": [ 34 ], "text": [ "connections between different electrical services" ] }
572f63e6b2c2fd14005680a8	Railway_electrification_system	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 bec...	Why the commuter lines built to different standards can cause be complicated?	{ "answer_start": [ 328 ], "text": [ "the implications on the sections it is connecting" ] }
572f63e6b2c2fd14005680a9	Railway_electrification_system	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 bec...	What is the solution many lines came up with in order to avoid replacing present rolling stock?	{ "answer_start": [ 400 ], "text": [ "to be overlaid with multiple electrification standards" ] }
572f63e6b2c2fd14005680aa	Railway_electrification_system	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 bec...	Why are disel trains still used on electrified routes?	{ "answer_start": [ 804 ], "text": [ "due to incompatibility of electrification standards" ] }
572f65c704bcaa1900d768d3	Railway_electrification_system	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 elec...	Which of two can be more efficiently electricified?	{ "answer_start": [ 0 ], "text": [ "Central station" ] }
572f65c704bcaa1900d768d4	Railway_electrification_system	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 elec...	How can electric power plant become more power efficient?	{ "answer_start": [ 366 ], "text": [ "it will shut down its least efficient generators" ] }
572f65c704bcaa1900d768d5	Railway_electrification_system	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 elec...	How can electric train be more energy efficient?	{ "answer_start": [ 506 ], "text": [ "by regenerative braking" ] }
572f65c704bcaa1900d768d6	Railway_electrification_system	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 elec...	Which type of train continues to use energy while coasting or being stopped?	{ "answer_start": [ 580 ], "text": [ "diesel" ] }
572f65c704bcaa1900d768d7	Railway_electrification_system	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 elec...	What causes electric trains to waste energy?	{ "answer_start": [ 668 ], "text": [ "cooling blowers" ] }
572f688cb2c2fd14005680e5	Railway_electrification_system	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 r...	Can renewable source of electricity be used in mobile power plants?	{ "answer_start": [ 15 ], "text": [ "unsuitable" ] }
572f688cb2c2fd14005680e7	Railway_electrification_system	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 r...	What is the recent incentive in order to overcome oil scarcity?	{ "answer_start": [ 569 ], "text": [ "to substitute other fuels" ] }
572f688cb2c2fd14005680e6	Railway_electrification_system	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 r...	What type of natural resources is more scarce?	{ "answer_start": [ 208 ], "text": [ "liquid fuel" ] }
572f688cb2c2fd14005680e8	Railway_electrification_system	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 r...	What research can be used in the future if translated?	{ "answer_start": [ 856 ], "text": [ "Soviet studies from the 1980s" ] }
572f6abab2c2fd14005680ed	Railway_electrification_system	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 term...	What type of trains became more energy-efficient in the former Soviet Union?	{ "answer_start": [ 28 ], "text": [ "electric" ] }
572f6abab2c2fd14005680ee	Railway_electrification_system	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 term...	What year could be marked as year when electric railways more efficient than diesel ones?	{ "answer_start": [ 461 ], "text": [ "1965" ] }
572f6abab2c2fd14005680ef	Railway_electrification_system	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 term...	How much fuel did electric train used less than diesel in the middle of 1970 in USSR?	{ "answer_start": [ 560 ], "text": [ "25% less fuel per ton-km" ] }
572f6abab2c2fd14005680f0	Railway_electrification_system	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 term...	What could be a factor of lower energy consumption for electric trains?	{ "answer_start": [ 742 ], "text": [ "better operating conditions on electrified lines" ] }
572f6abab2c2fd14005680f1	Railway_electrification_system	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 term...	How much more expensive was diesel compare to electricity per unit?	{ "answer_start": [ 905 ], "text": [ "1.5 times more (per unit of heat energy content" ] }
572f6d47a23a5019007fc60d	Railway_electrification_system	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...	What caused the energy efficiency to go up?	{ "answer_start": [ 158 ], "text": [ "energy-intensity dropping" ] }
572f6d47a23a5019007fc60f	Railway_electrification_system	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...	What type of locomotives got improved during 1950-1973 in Soviet Union?	{ "answer_start": [ 719 ], "text": [ "electric" ] }
572f6d47a23a5019007fc610	Railway_electrification_system	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...	How much of energy was saved and re-used due to regenerative braking in 1989?	{ "answer_start": [ 980 ], "text": [ "2.65%" ] }
572f6d47a23a5019007fc611	Railway_electrification_system	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...	Was there an energy efficiency improvement in the period 1974 through 1980?	{ "answer_start": [ 1328 ], "text": [ "no improvement" ] }
572f6d47a23a5019007fc60e	Railway_electrification_system	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...	Elimination of what helped the efficiency of diesel traction to go up?	{ "answer_start": [ 641 ], "text": [ "2-axle freight cars" ] }
572e867adfa6aa1500f8d09f	Spanish_language_in_the_United_States	The Spanish language is the second most spoken language in the United States. There are 45 million Hispanophones who speak Spanish as a first or second language in the United States, as well as six million Spanish language students. Together, this makes the United States of America the second largest Hispanophone count...	How many people speak Spanish as a first or second language in the United States?	{ "answer_start": [ 78 ], "text": [ "There are 45 million Hispanophones who speak Spanish as a first or second language in the United States," ] }
572e867adfa6aa1500f8d0a0	Spanish_language_in_the_United_States	The Spanish language is the second most spoken language in the United States. There are 45 million Hispanophones who speak Spanish as a first or second language in the United States, as well as six million Spanish language students. Together, this makes the United States of America the second largest Hispanophone count...	How many Hispanics speak English too?	{ "answer_start": [ 587 ], "text": [ "Roughly half of all American Spanish-speakers also speak English \"very well,\" based on their self-assessment in the U.S. Census." ] }
572e867adfa6aa1500f8d0a2	Spanish_language_in_the_United_States	The Spanish language is the second most spoken language in the United States. There are 45 million Hispanophones who speak Spanish as a first or second language in the United States, as well as six million Spanish language students. Together, this makes the United States of America the second largest Hispanophone count...	What type of language id Spanish?	{ "answer_start": [ 467 ], "text": [ "Spanish is the Romance language and the Indo-European language with the largest number of native speakers in the world." ] }
572e867adfa6aa1500f8d0a1	Spanish_language_in_the_United_States	The Spanish language is the second most spoken language in the United States. There are 45 million Hispanophones who speak Spanish as a first or second language in the United States, as well as six million Spanish language students. Together, this makes the United States of America the second largest Hispanophone count...	What other language is often spoken in the United states?	{ "answer_start": [ 0 ], "text": [ "The Spanish language is the second most spoken language in the United States." ] }
572e867adfa6aa1500f8d0a3	Spanish_language_in_the_United_States	The Spanish language is the second most spoken language in the United States. There are 45 million Hispanophones who speak Spanish as a first or second language in the United States, as well as six million Spanish language students. Together, this makes the United States of America the second largest Hispanophone count...	How many Spanish speaking students are there in the United States?	{ "answer_start": [ 194 ], "text": [ "six million Spanish language students." ] }
572e8a7bc246551400ce430c	Spanish_language_in_the_United_States	The Spanish language has been present in what is now the United States since the 16th and 17th centuries, with the arrival of Spanish colonization in North America that would later become the states of Florida, Texas, Colorado, New Mexico, Arizona, Nevada, Utah, and California. The Spanish explorers explored areas of 4...	How old is the Spanish language in the United States?	{ "answer_start": [ 0 ], "text": [ "The Spanish language has been present in what is now the United States since the 16th and 17th centuries" ] }
572e8a7bc246551400ce430e	Spanish_language_in_the_United_States	The Spanish language has been present in what is now the United States since the 16th and 17th centuries, with the arrival of Spanish colonization in North America that would later become the states of Florida, Texas, Colorado, New Mexico, Arizona, Nevada, Utah, and California. The Spanish explorers explored areas of 4...	Where in the United States did the Spanish explore?	{ "answer_start": [ 279 ], "text": [ "The Spanish explorers explored areas of 42 future U.S. states" ] }
572e8a7bc246551400ce430f	Spanish_language_in_the_United_States	The Spanish language has been present in what is now the United States since the 16th and 17th centuries, with the arrival of Spanish colonization in North America that would later become the states of Florida, Texas, Colorado, New Mexico, Arizona, Nevada, Utah, and California. The Spanish explorers explored areas of 4...	Were there states ruled by the Spanish?	{ "answer_start": [ 438 ], "text": [ "western regions of the Louisiana Territory were under Spanish rule between 1763 to 1800," ] }

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