1.
Hyundai Rotem
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Hyundai Rotem is a South Korean company manufacturing rolling stock, defense products and plant equipment. It is part of the Hyundai Motor Group and its name was changed to the current one from Rotem on December 2007 to reflect its parent company. The company subsequently changed its name to Railroading Technology System, or Rotem and it adopted its current name in December 2007 to reflect its current owner. Hyundai Rotem currently employs 3,800 and exported to 29 countries worldwide, notable projects include supplying most of South Koreas rolling stock, which include Korails KTX high speed trains, Electric multiple units, and Electric locomotives. Other products in South Korea includes supplying all of Seoul Metro, Seoul Metropolitan Rapid Transit and they are also to supply the Silverliner V commuter trains for SEPTA Regional Rail in the Philadelphia, Pennsylvania area. A. On 31 December 2014, Hyderabad Metro created a new record by successfully running a train in Automatic Train Operation mode for the first time on Indian soil between Nagole and Mettuguda. Hyundai Rotem announced on November 11,2008, that it had signed a contract to supply the rolling stock for the Marmaray cross-Bosporus tunnel project in Istanbul. The 22 m long stainless steel cars will be formed into 10, some production will be carried out locally by Eurotem, Hyundai Rotems joint venture with Turkish rolling stock manufacturer TÜVASAŞ. The cars will arrive in three batches, the first 160 cars by 2011, the last by June 2014, Hyundai Rotem won its first contract in Turkey in 1996, and has now completed seven orders for a total of 804 vehicles worth US$1·6bn. In July it signed a contract to provide 84 DMUs in conjunction with Tüvasas, Hyundai Rotem has earned the trust of Turkey by providing high quality products and technology, said Executive Vice-Chairman Yeo-Sung Lee. We believe this brightens the outlook for future opportunities in Turkey such as the Istanbul line. Hyundai Rotem was awarded a contract with Bostons MBTA in early 2008 for the construction of 75 cars, the contract entails the delivery of the first 4 cars by October 2010 while the remaining 71 cars were scheduled to be delivered by the end of 2012. However, due to delays, shoddy workmanship, material shortage. Lee, in November 2012, only four cars have been delivered by the end of 2012. On December 21,2012, the MBTA sent a letter to Hyundai Rotem threatening to cancel the contract if a solution is not soon reached, since then, the new cars have continued to experience various mechanical problems resulting in car shortages and delays. Economy of South Korea CRRC Corporation Bombardier Transportation Siemens Mobility Hyundai Rotem web site
2.
South Philadelphia
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South Philadelphia, nicknamed South Philly, is the section of Philadelphia bounded by South Street to the north, the Delaware River to the east and south, and the Schuylkill River to the west. A diverse community, South Philadelphia is known for its large Italian American population, South Philadelphia also contains large Irish American and African American populations as well. South Philadelphia began as a town of Philadelphia, with small townships such as Moyamensing. Towards the end of the Industrial Revolution, the area saw rapid growth in population, South Philadelphias urbanized border eventually expanded to reach that of Philadelphia proper, or what is today known as Center City Philadelphia. The immigrants and migrants became the basis of South Philadelphias unique, the later immigrant populations of Italians and Poles were also Catholic. Initially, these populations attended existing Catholic churches but built their own ethno-national churches when possible, a smaller but significant Greek immigrant community also flourished around this time, leading to the establishment of Greek Orthodox parishes in South Philadelphia. Despite this dramatic growth in population, the low funding of education by the city resulted in the first public high school not being formed in South Philadelphia until 1934. Attracted to the jobs, the new residents of South Philadelphia created communities that continued many of their Old World traditions. While many of the new arrivals were Catholic, neighborhood parishes reflected their ethnic, monsignor James F. Today, many of South Philadelphias communities are largely Italian American. In addition, South Philadelphia continues to be home to many ethnic Irish American communities, the neighborhood of Pennsport remains primarily a working class Irish-American neighborhood and the cultural center of Irish-American South Philadelphia. In addition, there has been an increase in recent years of immigrants from Russia, Mexico, and Central American nations such as Honduras, Guatemala, portions of South Philadelphia are within Philadelphia City Council Districts 1 and 2. As of 2014 Councilman Mark Squilla and Councilman Kenyatta Johnson represent the two districts, the Philadelphia Fire Department operates nine fire stations serving South Philadelphia. Most of South Philadelphia resides in Fire Battalion 1, headquartered at 711 South Broad Street, portions of South Philadelphia reside in Battalion 4, headquartered at North 4th Street and Arch Street, and Battalion 11, headquartered at 43rd Street and Market Street. The Philadelphia Police Department patrols three districts located within South Philadelphia, the three patrol districts serving South Philadelphia are the 1st, 3rd, and 17th districts. According to the United States Census Bureau, South Philadelphia has an area of 9.7 sq. miles, in 2010, the areas population was 168,782. In addition, the area contains smaller but historically significant Greek American, many residents have lived in the neighborhood for decades. Many family-owned businesses are found in South Philadelphia, on January 22,2010 the Associated Press said South Philadelphia has been growing more diverse for decades, but the last 20 years have seen the greatest influx of Asian and Hispanic families. David Elesh, a Temple University urban sociologist, said that of the almost 60,000 Philadelphia residents who reported being born in China, as of the 2010 Census, there are 168,782 people in 78,440 housing units
3.
Pennsylvania
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Pennsylvania /ˌpɛnsᵻlˈveɪnjə/, officially the Commonwealth of Pennsylvania, is a state located in the northeastern and Mid-Atlantic regions of the United States. The Appalachian Mountains run through its middle, Pennsylvania is the 33rd largest, the 5th most populous, and the 9th most densely populated of the 50 United States. The states five most populous cities are Philadelphia, Pittsburgh, Allentown, Erie, the state capital, and its ninth-largest city, is Harrisburg. Pennsylvania has 140 miles of shoreline along Lake Erie and the Delaware Estuary. The state is one of the 13 original founding states of the United States, it came into being in 1681 as a result of a land grant to William Penn. Part of Pennsylvania, together with the present State of Delaware, had earlier been organized as the Colony of New Sweden and it was the second state to ratify the United States Constitution, on December 12,1787. Independence Hall, where the United States Declaration of Independence and United States Constitution were drafted, is located in the states largest city of Philadelphia, during the American Civil War, the Battle of Gettysburg, was fought in the south central region of the state. Valley Forge near Philadelphia was General Washingtons headquarters during the winter of 1777–78. Pennsylvania is 170 miles north to south and 283 miles east to west, of a total 46,055 square miles,44,817 square miles are land,490 square miles are inland waters, and 749 square miles are waters in Lake Erie. It is the 33rd largest state in the United States, Pennsylvania has 51 miles of coastline along Lake Erie and 57 miles of shoreline along the Delaware Estuary. Cities include Philadelphia, Reading, Lebanon and Lancaster in the southeast, Pittsburgh in the southwest, the tri-cities of Allentown, Bethlehem, the northeast includes the former anthracite coal mining communities of Scranton, Wilkes-Barre, Pittston City, and Hazleton. Erie is located in the northwest, the state has 5 regions, namely the Allegheny Plateau, Ridge and Valley, Atlantic Coastal Plain, Piedmont, and the Erie Plain. Straddling two major zones, the majority of the state, with the exception of the corner, has a humid continental climate. The largest city, Philadelphia, has characteristics of the humid subtropical climate that covers much of Delaware. Moving toward the interior of the state, the winter climate becomes colder, the number of cloudy days increase. Western areas of the state, particularly locations near Lake Erie, can receive over 100 inches of snowfall annually, the state may be subject to severe weather from spring through summer into fall. Tornadoes occur annually in the state, sometimes in large numbers, the Tuscarora Nation took up temporary residence in the central portion of Pennsylvania ca. Both the Dutch and the English claimed both sides of the Delaware River as part of their lands in America
4.
Silverliner
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Silverliner is the name given to a series of electric multiple unit railcars in commuter rail service in the Philadelphia area since 1958. As of the introduction of the Silverliner V in 2009-2010, there have been 5 generations of Silverliner cars, what came to be known as the Silverliner Is were a set of 6 pilot EMUs making use of Budds prototype Pioneer III railcar design. The 6 Pioneer III cars were purchased in response to the age of the PRRs MP54 fleet. As other railroads adopted new technology MUs like the New York Central ACMU, in 1958 the PRR placed an order with the Philadelphia-based Budd Company for 6 Pioneer III MU cars in two subclasses to test out various options. Numbered 150 to 155 the even-numbered cars had fabricated truck frames and disc brakes, while the cars had cast steel truck frames. The PRR initially had hopes to MU cars such as the Pioneer IIIs in intercity service along its electrified routes, however as testing went on they were soon limited to suburban service in the Philadelphia area when a full-scale production order of 38 PRR Silverliner cars were delivered in 1963. The 6th car, which would have been #249, had already written off in an accident by that time. While the other Silverliner models all came with similar GE propulsion gear, they could not MU with the earlier Silverliner I cars, until 2000, the cars were kept in storage near Wayne Junction. In 1963 the financial condition of the Pennsylvania and Reading Railroads was such that neither was able to upgrade their money losing commuter operations on their own. The new cars would be an order based on 61958 Pioneer III type cars with improvements based on the lessons learned from the earlier design. A total of 38 cars were purchased for the PRR with the remaining 17 going to the Reading, while some referred to the new vehicles as PSIC Cars, the modern stainless steel body shells quickly defined the fleet and the name Silverliner was soon adopted. Like the Pioneer IIIs before them, the Silverliners offered their riders air cushion suspension, air conditioning, electric train heat and a nearly silent ride. The 38 PRR cars were numbered in two series, 201-219 and 251-269 and given PRR classification MP85B, while the 17 Reading cars were numbered 9001-9017 and given Reading classification REB-13. With the delivery of the set of Silverliners in 1967. After 1976 the service continued to be operated under Conrail, but was branded as SEPTA. In 1989 the entire fleet was sent to the Morrison-Knudsen plant in Hornell, however a prolonged procurement process as well as delays in delivering the replacement Silverliner V cars resulted in the Budds lasting in service well into 2012, a run of nearly 50 years. The final run took place on June 29,2012 with former Reading car #9010 running with Silverliner III #235 on the Cynwyd Line. Numbered T-1 through T-4, the cars were modified for operation up to speeds of 150 mph and were outfitted with instrumentation to document the effects of rail travel at such speeds
5.
SEPTA
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SEPTA also manages construction projects that maintain, replace, and expand infrastructure and rolling stock. SEPTA is the transit provider for Philadelphia and its suburbs in Delaware, Montgomery, Bucks. SEPTA is a state created authority and the majority of its board is appointed by the five Pennsylvania counties it serves. SEPTA has the 6th-largest U. S. rapid transit system by ridership, and it controls 290 active stations, over 450 miles of track,2,295 revenue vehicles, and 196 routes. SEPTA also manages Shared-Ride services in Philadelphia and ADA services across the region and these services are operated by third-party contractors. SEPTA is one of only two U. S. SEPTAs headquarters are located at 1234 Market Street in Center City, SEPTA was created by the Pennsylvania legislature on August 17,1963, to coordinate government subsidies to various transit and railroad companies in southeastern Pennsylvania. It commenced on February 18,1964, by 1966, the Reading Company and Pennsylvania Railroad commuter railroad lines were operated under contract to SEPTA. On February 1,1968, the Pennsylvania Railroad merged with the New York Central railroad to become Penn Central, Penn Central continued to operate in bankruptcy until 1976, when Conrail took over its assets along with those of several other bankrupt railroads, including the Reading Company. Conrail operated commuter services under contract to SEPTA until January 1,1983, when SEPTA took over operations and acquired track, rolling stock, and other assets to form the Railroad Division. Since 1913, a long proposed Roosevelt Boulevard Subway had a similar fate as New Yorks Second Avenue Subway where many proposals were made, many acquisitions had been made, but only amounted to continuous service cuts through consolidations of competing services of the Reading Railroad and Pennsylvania Railroad. It wasnt until the early 2000s that there was any talk of expansion, the PTC had been created in 1940 with the merger of the Philadelphia Rapid Transit Company and a group of smaller, then independent transit companies operating within the city and its environs. Today, this is the Victory Division, though it is referred to as the Red Arrow Division. On March 1,1976, SEPTA acquired the operations of Schuylkill Valley Lines. Future expansion of SEPTAs commuter rail lines has been discussed since the mid-1980s when the system suffered severe cutbacks, proposals have been made to restore service to Allentown, Bethlehem, West Chester and Newtown, with support from commuters, local officials and pro-train advocates. The Schuylkill Valley Metro and other plans that would re-establish service to Phoenixville, Pottsville, SEPTA has also considered the possibility of a cross-county metro that would provide service between the suburban counties without requiring the rider to go into Philadelphia. However, many derelict lines under SEPTA ownership have been converted to rail trails, additionally, some, such as Senator Bob Casey, have proposed expanding the Broad Street Line to the Philadelphia Naval Shipyard. Proposals have also made for increased service on existing lines, including later evenings and Sundays to Wilmington. Marylands MARC commuter rail system is considering extending its service as far as Newark Rail Station, as of 2014, an expansion of the Norristown High Speed Line is under consideration to extend service to the King of Prussia area
6.
Regional Transportation District
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It operates over a 2, 340-square-mile area, serving 2.87 million people. RTD is governed by a 15-member, publicly elected Board of Directors, Directors are elected to a four-year term and represent a specific district of about 180,000 constituents. RTD currently operates a bus and rail system that has an area of 2,337 square miles. It employed 2,734 people and reported 103 million boardings in 2016 and it had a $466.7 million operating budget for the year of 2015. Google has RTD schedules attached to its trip planner, and 3rd party mobile applications are now available for the iPhone,1969, RTD was created in the 47th session of the Colorado General Assembly to provide public transportation to five additional counties in the metropolitan area. 1969–1971, The Denver Tramway Company continues service under sponsorship of the City and County of Denver, October 1970, RTD found it needed to establish a Northern Operations Group to provide service to Boulder and Longmont. RTD also acquired the privately owned Denver-Boulder Bus Company, which ran airport buses,1971, Denver Metro Transit took over the privately owned Denver Tramway Company. Denver Metro Transit was an entity created by the City and County of Denver, suburban service only continued for those suburbs willing to contribute a subsidy. 1972, RTD created a plan for a rapid transit system in the area. This plan included 98 miles of PRT and extensive bus service throughout the areas served by RTD, later that year, the Urban Mass Transportation Administration selected RTD to develop PRT as a demonstration project. The PRT project was eventually scrapped, the tax became effective January 1,1974. July 1974, Denver Metro Transit became part of RTD, 1975–1977, RTD consolidated, expanded, and improved service frequency. Service was expanded to routes that commercial carriers previously operated, february 1978, Inflation caused RTD to implement a new fare structure. For instances, the new Colorado Blvd route was number 40,1979, Federal approval was granted for the 16th Street Mall in downtown Denver, originally known as Transitway. The project allowed express bus productivity to double and was intersected by RTDs first light rail line. 1980, RTD reached a number of weekday passengers. It also acquired 216 new buses,89 of which were articulated, construction began on the 16th Street Mall. Work was also completed to make RTDs service more accessible to elderly,1983, On May 1,1983, the tax was increased to 0. 6%
7.
SEPTA Regional Rail
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The SEPTA Regional Rail system consists of commuter rail service on 13 branches to more than 150 active stations in Philadelphia, Pennsylvania, and its suburbs and satellite cities. Service on most lines operates from 5,30 a. m. to midnight and it is the fifth-busiest commuter railroad in the United States and busiest outside of the New York and Chicago metropolitan areas. In 2016, Regional Rail had an average of 132,000 daily riders, All trains stop at these Center City stations, most also stop at Temple University station on the campus of Temple University in North Philadelphia. Operations are handled by the SEPTA Railroad Division, of the 13 branches, seven were originally owned and operated by the Pennsylvania Railroad, and six by the Reading Company. The PRR lines terminated at Suburban Station, the Reading lines at Reading Terminal, in November 1984, the Center City Commuter Connection united the two systems, turning the two terminal stations into through-stations. Most inbound trains from one line continue on as outbound trains on another line. Each PRR line was paired with a Reading branch and numbered from R1 to R8. Former Pennsylvania Railroad lines Airport Line, terminates at the Philadelphia International Airport, Chestnut Hill West Line, terminates in the Chestnut Hill section of Philadelphia. Cynwyd Line, terminates in Cynwyd and operates weekdays only, until 1986, trains continued on to Ivy Ridge station in northwestern Philadelphia. Until 1986, trains continued on to West Chester, SEPTA is in the process of restoring service to Wawa, approximately three miles west of Elwyn by 2020. Paoli/Thorndale Line, trains terminate at Malvern or Thorndale, additional rush hour trains terminate at Bryn Mawr, Trenton Line, terminates in Trenton, New Jersey. This line uses Amtraks Northeast Corridor, and offers a connection at Trenton to New Jersey Transits Northeast Corridor Line for continued service to New York City, wilmington/Newark Line, terminates in Wilmington, Delaware, with some weekday trains continuing to Newark, Delaware. The Delaware Department of Transportation subsidizes Delaware service and this line runs entirely on Amtraks Northeast Corridor. Former Reading Company lines Chestnut Hill East Line, terminates in the Chestnut Hill section of Philadelphia, Fox Chase Line, terminates in the Fox Chase section of Philadelphia. Until 1983, connecting diesel trains continued to Newtown, Pennsylvania, on weekdays, approximately half of the local trains terminate at Lansdale while the remainder of the local trains, and some expresses, continue on to Doylestown. Manayunk/Norristown Line, terminates at Elm Street in Norristown, West Trenton Line, terminates at the West Trenton station in Ewing, New Jersey. In 2003, passengers boarding in Philadelphia accounted for 61% of trips on a typical weekday, SEPTA uses a mixed fleet of General Electric and Hyundai Rotem Silverliner electric multiple unit cars, used on all Regional Rail lines. SEPTAs railroad reporting mark SEPA is the mark for their revenue equipment
8.
Stainless steel
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In metallurgy, stainless steel, also known as inox steel or inox from French inoxydable, is a steel alloy with a minimum of 10. 5% chromium content by mass. Stainless steel is notable for its resistance, and it is widely used for food handling. Stainless steel does not readily corrode, rust or stain with water as ordinary steel does, however, it is not fully stain-proof in low-oxygen, high-salinity, or poor air-circulation environments. There are various grades and surface finishes of stainless steel to suit the environment the alloy must endure, Stainless steel is used where both the properties of steel and corrosion resistance are required. Stainless steel differs from carbon steel by the amount of chromium present, unprotected carbon steel rusts readily when exposed to air and moisture. This iron oxide film is active and accelerates corrosion by making it easier for more iron oxide to form, since iron oxide has lower density than steel, the film expands and tends to flake and fall away. In comparison, stainless steels contain sufficient chromium to undergo passivation and this layer prevents further corrosion by blocking oxygen diffusion to the steel surface and stops corrosion from spreading into the bulk of the metal. Passivation occurs only if the proportion of chromium is high enough, Stainless steel’s resistance to corrosion and staining, low maintenance, and familiar lustre make it an ideal material for many applications. Storage tanks and tankers used to transport orange juice and other food are made of stainless steel. This also influences its use in kitchens and food processing plants, as it can be steam-cleaned and sterilized. High oxidation resistance in air at ambient temperature is achieved with addition of a minimum of 13% chromium. The chromium forms a layer of chromium oxide when exposed to oxygen. The layer is too thin to be visible, and the metal remains lustrous, the layer is impervious to water and air, protecting the metal beneath, and this layer quickly reforms when the surface is scratched. This phenomenon is called passivation and is seen in other metals, corrosion resistance can be adversely affected if the component is used in a non-oxygenated environment, a typical example being underwater keel bolts buried in timber. When stainless steel parts such as nuts and bolts are forced together, when forcibly disassembled, the welded material may be torn and pitted, a destructive effect known as galling. Galling can be avoided by the use of materials for the parts forced together, for example bronze and stainless steel. However, two different alloys electrically connected in a humid, even mildly acidic environment may act as a voltaic pile, nitronic alloys, made by selective alloying with manganese and nitrogen, may have a reduced tendency to gall. Additionally, threaded joints may be lubricated to provide a film between the two parts and prevent galling, low-temperature carburizing is another option that virtually eliminates galling and allows the use of similar materials without the risk of corrosion and the need for lubrication
9.
Induction motor
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An induction motor can therefore be made without electrical connections to the rotor. An induction motors rotor can be either wound type or squirrel-cage type, three-phase squirrel-cage induction motors are widely used in industrial drives because they are rugged, reliable and economical. Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans, although traditionally used in fixed-speed service, induction motors are increasingly being used with variable-frequency drives in variable-speed service. VFDs offer especially important energy savings opportunities for existing and prospective induction motors in variable-torque centrifugal fan, pump, squirrel cage induction motors are very widely used in both fixed-speed and variable-frequency drive applications. Tesla applied for U. S. patents in October and November 1887 and was granted some of these patents in May 1888, in April 1888, the Royal Academy of Science of Turin published Ferrariss research on his AC polyphase motor detailing the foundations of motor operation. George Westinghouse, who was developing an alternating current power system at time, licensed Tesla’s patents in 1888. Tesla was also employed for one year as a consultant, Westinghouse employee C. F. Scott was assigned to assist Tesla and later took over development of the induction motor at Westinghouse. Steadfast in his promotion of development, Mikhail Dolivo-Dobrovolsky invented the cage-rotor induction motor in 1889. Furthermore, he claimed that Teslas motor was not practical because of two-phase pulsations, G. Lamme developed a rotating bar winding rotor. The General Electric Company began developing three-phase induction motors in 1891, by 1896, General Electric and Westinghouse signed a cross-licensing agreement for the bar-winding-rotor design, later called the squirrel-cage rotor. Arthur E. Kennelly was the first to bring out full significance of the i to designate the 90-degree rotation operator in complex number analysis of AC problems. GEs Charles Proteus Steinmetz greatly developed application of AC complex quantities including in terms now commonly known as the induction motors Steinmetz equivalent circuit. Induction motor improvements flowing from these inventions and innovations were such that a 100-horsepower induction motor currently has the same mounting dimensions as a 7. 5-horsepower motor in 1897. In both induction and synchronous motors, the AC power supplied to the motors stator creates a field that rotates in time with the AC oscillations. Whereas a synchronous motors rotor turns at the rate as the stator field. The induction motor stators magnetic field is changing or rotating relative to the rotor. This induces a current in the induction motors rotor, in effect the motors secondary winding. The rotating magnetic flux induces currents in the windings of the rotor, the currents in the rotor windings in turn create magnetic fields in the rotor that react against the stator field
10.
Variable-frequency drive
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A variable-frequency drive is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage. VFDs are used in applications ranging from small appliances to the largest of mine mill drives and that lack of penetration highlights significant energy efficiency improvement opportunities for retrofitted and new VFD installations. VFDs are available in a number of different low- and medium-voltage AC-AC and DC-AC topologies, a variable-frequency drive is a device used in a drive system consisting of the following three main sub-systems, AC motor, main drive controller assembly, and drive/operator interface. The AC electric motor used in a VFD system is usually three-phase induction motor, motors that are designed for fixed-speed operation are often used. The VFD controller is a power electronics conversion system consisting of three distinct sub-systems, a rectifier bridge converter, a direct current link, and an inverter. Voltage-source inverter drives are by far the most common type of drives, most drives are AC-AC drives in that they convert AC line input to AC inverter output. However, in applications such as common DC bus or solar applications. The most basic rectifier converter for the VSI drive is configured as a three-phase, six-pulse, in a VSI drive, the DC link consists of a capacitor which smooths out the converters DC output ripple and provides a stiff input to the inverter. This filtered DC voltage is converted to quasi-sinusoidal AC voltage output using the active switching elements. VSI drives provide higher power factor and lower distortion than phase-controlled current-source inverter. The drive controller can also be configured as a phase converter having single-phase converter input, controller advances have exploited dramatic increases in the voltage and current ratings and switching frequency of solid-state power devices over the past six decades. Introduced in 1983, the bipolar transistor has in the past two decades come to dominate VFDs as an inverter switching device. For example, for 460 V,60 Hz motors, this linear V/Hz relationship is 460/60 =7.67 V/Hz, some V/Hz control drives can also operate in quadratic V/Hz mode or can even be programmed to suit special multi-point V/Hz paths. Although space vector pulse-width modulation is becoming popular, sinusoidal PWM is the most straightforward method used to vary drives motor voltage. Operation of the motors above rated nameplate speed is possible, but is limited to conditions that do not require more power than the rating of the motor. This is sometimes called field weakening and, for AC motors, means operating at less than rated V/Hz, permanent magnet synchronous motors have quite limited field-weakening speed range due to the constant magnet flux linkage. Wound-rotor synchronous motors and induction motors have much wider speed range, for example, a 100 HP,460 V,60 Hz,1775 RPM induction motor supplied with 460 V,75 Hz, would be limited to 60/75 = 80% torque at 125% speed = 100% power. At higher speeds, the motor torque has to be limited further due to the lowering of the breakaway torque of the motor
11.
Railway electrification system
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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, 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, 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 lines, switches and transformers. Power is supplied to moving trains with a continuous conductor running along the track usually takes one of two forms. The first is a line or catenary wire suspended from poles or towers along the track or from structure or tunnel ceilings. Locomotives or multiple units pick up power from the wire with pantographs on their roofs that press a conductive strip against it with a spring or air pressure. Examples are described later in this article, the second is a third rail mounted at track level and contacted by a sliding pickup shoe. Both overhead wire and third-rail systems usually use the rails as the return conductor. In comparison to the alternative, the diesel engine, electric railways offer substantially better energy efficiency, lower emissions. Electric locomotives are usually quieter, more powerful, and more responsive and they have no local emissions, an important advantage in tunnels and urban areas. 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. Possible lethal electric current due to risk of contact with high-voltage contact wires, overhead wires are safer than third rails, but they are often considered unsightly. These are independent of the system used, so that. The permissible range of voltages allowed for the voltages is as stated in standards BS EN50163. These take into account the number of trains drawing current and their distance from the substation, railways must operate at variable speeds. Until the mid 1980s this was only practical with the brush-type DC motor, 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 and trams
12.
Volt
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The volt is the derived unit for electric potential, electric potential difference, and electromotive force. One volt is defined as the difference in potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. It is also equal to the difference between two parallel, infinite planes spaced 1 meter apart that create an electric field of 1 newton per coulomb. Additionally, it is the difference between two points that will impart one joule of energy per coulomb of charge that passes through it. It can also be expressed as amperes times ohms, watts per ampere, or joules per coulomb, for the Josephson constant, KJ = 2e/h, the conventional value KJ-90 is used, K J-90 =0.4835979 GHz μ V. This standard is typically realized using an array of several thousand or tens of thousands of junctions. Empirically, several experiments have shown that the method is independent of device design, material, measurement setup, etc. in the water-flow analogy sometimes used to explain electric circuits by comparing them with water-filled pipes, voltage is likened to difference in water pressure. Current is proportional to the diameter of the pipe or the amount of water flowing at that pressure. A resistor would be a reduced diameter somewhere in the piping, the relationship between voltage and current is defined by Ohms Law. Ohms Law is analogous to the Hagen–Poiseuille equation, as both are linear models relating flux and potential in their respective systems, the voltage produced by each electrochemical cell in a battery is determined by the chemistry of that cell. Cells can be combined in series for multiples of that voltage, mechanical generators can usually be constructed to any voltage in a range of feasibility. High-voltage electric power lines,110 kV and up Lightning, Varies greatly. Volta had determined that the most effective pair of metals to produce electricity was zinc. In 1861, Latimer Clark and Sir Charles Bright coined the name volt for the unit of resistance, by 1873, the British Association for the Advancement of Science had defined the volt, ohm, and farad. In 1881, the International Electrical Congress, now the International Electrotechnical Commission and they made the volt equal to 108 cgs units of voltage, the cgs system at the time being the customary system of units in science. At that time, the volt was defined as the difference across a conductor when a current of one ampere dissipates one watt of power. The international volt was defined in 1893 as 1/1.434 of the emf of a Clark cell and this definition was abandoned in 1908 in favor of a definition based on the international ohm and international ampere until the entire set of reproducible units was abandoned in 1948. Prior to the development of the Josephson junction voltage standard, the volt was maintained in laboratories using specially constructed batteries called standard cells
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