In Indian Railways , A MEMU is an electric multiple unit (EMU) train that serves short and medium-distance routes in India, as compared to normal EMU trains that connect urban and suburban areas. The acronym stands for Mainline Electric Multiple Unit .
88-502: Indian Railways (IR) started MEMU service on Asansol – Adra section on 15 July 1995 and on Kharagpur – Tata section on 22 July 1995. Delhi-Panipat MEMU service started on 27 September 1995. Raipur–Durg–Bhatapara–Raipur–Bilaspur MEMU service started on 17 October 1995. Arakkonam-Jolarpettai MEMU service on 22 May 2000. Bankura-Midnapore MEMU started on 30 June 2000. The first 20 coach MEMU ran between Surat to Virar in 2017. Since 2019, 3-phase MEMUs have started replacing existing MEMU rakes. IR
176-399: A ferromagnetic core. Electric current passing through the wire causes the magnetic field to exert a force ( Lorentz force ) on it, turning the rotor. Windings are coiled wires, wrapped around a laminated, soft, iron, ferromagnetic core so as to form magnetic poles when energized with current. Electric machines come in salient- and nonsalient-pole configurations. In a salient-pole motor
264-430: A magnetic field that passes through the rotor armature, exerting force on the rotor windings. The stator core is made up of many thin metal sheets that are insulated from each other, called laminations. These laminations are made of electrical steel , which has a specified magnetic permeability, hysteresis, and saturation. Laminations reduce losses that would result from induced circulating eddy currents that would flow if
352-1433: A wire winding to generate force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric motor, but operates in reverse, converting mechanical energy into electrical energy. Electric motors can be powered by direct current (DC) sources, such as from batteries or rectifiers , or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. Electric motors may be classified by considerations such as power source type, construction, application and type of motion output. They can be brushed or brushless , single-phase , two-phase , or three-phase , axial or radial flux , and may be air-cooled or liquid-cooled. Standardized motors provide power for industrial use. The largest are used for ship propulsion, pipeline compression and pumped-storage applications, with output exceeding 100 megawatts . Applications include industrial fans, blowers and pumps, machine tools, household appliances, power tools, vehicles, and disk drives. Small motors may be found in electric watches. In certain applications, such as in regenerative braking with traction motors , electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction. Electric motors produce linear or rotary force ( torque ) intended to propel some external mechanism. This makes them
440-404: A 100- horsepower induction motor currently has the same mounting dimensions as a 7.5-horsepower motor in 1897. In 2022, electric motor sales were estimated to be 800 million units, increasing by 10% annually. Electric motors consume ≈50% of the world's electricity. Since the 1980s, the market share of DC motors has declined in favor of AC motors. An electric motor has two mechanical parts:
528-431: A 20-hp squirrel cage and a 100-hp wound rotor with a starting rheostat. These were the first three-phase asynchronous motors suitable for practical operation. Since 1889, similar developments of three-phase machinery were started Wenström. At the 1891 Frankfurt International Electrotechnical Exhibition, the first long distance three-phase system was successfully presented. It was rated 15 kV and extended over 175 km from
616-464: A commutator-type direct-current electric motor was built by American inventors Thomas Davenport and Emily Davenport , which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools and a printing press. Due to the high cost of primary battery power , the motors were commercially unsuccessful and bankrupted the Davenports. Several inventors followed Sturgeon in
704-463: A comparatively small air gap. The St. Louis motor, long used in classrooms to illustrate motor principles, is inefficient for the same reason, as well as appearing nothing like a modern motor. Electric motors revolutionized industry. Industrial processes were no longer limited by power transmission using line shafts, belts, compressed air or hydraulic pressure. Instead, every machine could be equipped with its own power source, providing easy control at
792-607: A cost-effective solution for a water reservoir in a micro-pumped hydro energy storage. Such plants provide distributed energy storage and distributed flexible electricity production and can contribute to the decentralized integration of intermittent renewable energy technologies, such as wind power and solar power . Reservoirs that can be used for small pumped-storage hydropower plants could include natural or artificial lakes, reservoirs within other structures such as irrigation, or unused portions of mines or underground military installations. In Switzerland one study suggested that
880-436: A four-week test of a pumped storage underwater reservoir. In this configuration, a hollow sphere submerged and anchored at great depth acts as the lower reservoir, while the upper reservoir is the enclosing body of water. Electricity is created when water is let in via a reversible turbine integrated into the sphere. During off-peak hours, the turbine changes direction and pumps the water out again, using "surplus" electricity from
968-422: A generator and the other as motor. The drum rotor was introduced by Friedrich von Hefner-Alteneck of Siemens & Halske to replace Pacinotti's ring armature in 1872, thus improving the machine efficiency. The laminated rotor was introduced by Siemens & Halske the following year, achieving reduced iron losses and increased induced voltages. In 1880, Jonas Wenström provided the rotor with slots for housing
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#17328844584601056-479: A hybrid system that both generates power from water naturally flowing into the reservoir as well as storing water pumped back to the reservoir from below the dam. The Grand Coulee Dam in the United States was expanded with a pump-back system in 1973. Existing dams may be repowered with reversing turbines thereby extending the length of time the plant can operate at capacity. Optionally a pump back powerhouse such as
1144-462: A maximum permitted speed of 105 km/h (65 mph) on broad-gauge tracks. The motorcoaches use DC traction motors. These rakes use asynchronous traction motors and have a maximum designed speed of 110 km/h. These use a stainless steel body. Two of them operate on South Central Railways . ICF launched new MEMUs capable to operate at 110–130 km/h. The construction cost is ₹ 26 crore per unit and can carry 2,618 passengers. This train has
1232-437: A model electric vehicle that same year. A major turning point came in 1864, when Antonio Pacinotti first described the ring armature (although initially conceived in a DC generator, i.e. a dynamo). This featured symmetrically grouped coils closed upon themselves and connected to the bars of a commutator, the brushes of which delivered practically non-fluctuating current. The first commercially successful DC motors followed
1320-404: A pump and as a turbine generator (usually Francis turbine designs). Variable speed operation further optimizes the round trip efficiency in pumped hydro storage plants. In micro-PSH applications, a group of pumps and Pump As Turbine (PAT) could be implemented respectively for pumping and generating phases. The same pump could be used in both modes by changing rotational direction and speed:
1408-585: A reservoir. The largest one, Saurdal, which is part of the Ulla-Førre complex, has four 160 MW Francis turbines , but only two are reversible. The lower reservoir is at a higher elevation than the station itself, and thus the water pumped up can only be used once before it has to flow to the next station, Kvilldal, further down the tunnel system. And in addition to the lower reservoir, it will receive water that can be pumped up from 23 river/stream and small reservoir intakes. Some of which will have already gone through
1496-425: A rotating bar winding rotor. Steadfast in his promotion of three-phase development, Mikhail Dolivo-Dobrovolsky invented the three-phase induction motor in 1889, of both types cage-rotor and wound rotor with a starting rheostat, and the three-limb transformer in 1890. After an agreement between AEG and Maschinenfabrik Oerlikon , Doliwo-Dobrowolski and Charles Eugene Lancelot Brown developed larger models, namely
1584-473: A significant amount of energy is by having a large body of water located relatively near, but as high as possible above, a second body of water. In some places this occurs naturally, in others one or both bodies of water were man-made. Projects in which both reservoirs are artificial and in which no natural inflows are involved with either reservoir are referred to as "closed loop" systems. These systems may be economical because they flatten out load variations on
1672-641: A similar role in the electrical grid as pumped storage if appropriately equipped. Taking into account conversion losses and evaporation losses from the exposed water surface, energy recovery of 70–80% or more can be achieved. This technique is currently the most cost-effective means of storing large amounts of electrical energy, but capital costs and the necessity of appropriate geography are critical decision factors in selecting pumped-storage plant sites. The relatively low energy density of pumped storage systems requires either large flows and/or large differences in height between reservoirs. The only way to store
1760-437: A smaller power station on its way. In 2010, the United States had 21.5 GW of pumped storage generating capacity (20.6% of world capacity). PSH contributed 21,073 GWh of energy in 2020 in the United States, but −5,321 GWh (net) because more energy is consumed in pumping than is generated. Nameplate pumped storage capacity had grown to 21.6 GW by 2014, with pumped storage comprising 97% of grid-scale energy storage in
1848-398: A solid core were used. Mains powered AC motors typically immobilize the wires within the windings by impregnating them with varnish in a vacuum. This prevents the wires in the winding from vibrating against each other which would abrade the wire insulation and cause premature failures. Resin-packed motors, used in deep well submersible pumps, washing machines, and air conditioners, encapsulate
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#17328844584601936-703: A three phase traction motor and operates on 25 kV current which saves 35% energy. It offers GPS -based passenger information systems and announcement in coaches. It has double leaf sliding doors, gangways, CCTV cameras and aluminium luggage racks. The driver's cabin has AC and the coach has an emergency communication facility. It is designed to operate between cities 200–300 km (120–190 mi) away in Uttar Pradesh . The train may start in February 2019. MEMUs are manufactured at Rail Coach Factory, Kapurthala , and Integral Coach Factory , Chennai . Rakes are maintained in
2024-525: A total installed capacity of 1344 MW and an average annual production of 2247 GWh. The pumped storage hydropower in Norway is built a bit differently from the rest of the world. They are designed for seasonal pumping. Most of them can also not cycle the water endlessly, but only pump and reuse once. The reason for this is the design of the tunnels and the elevation of lower and upper reservoirs. Some, like Nygard power station, pump water from several river intakes up to
2112-518: A total installed storage capacity of over 1.6 TWh . A pumped-storage hydroelectricity generally consists of two water reservoirs at different heights, connected with each other. At times of low electrical demand, excess generation capacity is used to pump water into the upper reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine , generating electricity. Pumped storage plants usually use reversible turbine/generator assemblies, which can act both as
2200-579: A type of actuator . They are generally designed for continuous rotation, or for linear movement over a significant distance compared to its size. Solenoids also convert electrical power to mechanical motion, but over only a limited distance. Before modern electromagnetic motors, experimental motors that worked by electrostatic force were investigated. The first electric motors were simple electrostatic devices described in experiments by Scottish monk Andrew Gordon and American experimenter Benjamin Franklin in
2288-488: A world record, which Jacobi improved four years later in September 1838. His second motor was powerful enough to drive a boat with 14 people across a wide river. It was also in 1839/40 that other developers managed to build motors with similar and then higher performance. In 1827–1828, Jedlik built a device using similar principles to those used in his electromagnetic self-rotors that was capable of useful work. He built
2376-592: A wound rotor forming a self-starting induction motor , and the third a true synchronous motor with separately excited DC supply to rotor winding. One of the patents Tesla filed in 1887, however, also described a shorted-winding-rotor induction motor. George Westinghouse , who had already acquired rights from Ferraris (US$ 1,000), promptly bought Tesla's patents (US$ 60,000 plus US$ 2.50 per sold hp, paid until 1897), employed Tesla to develop his motors, and assigned C.F. Scott to help Tesla; however, Tesla left for other pursuits in 1889. The constant speed AC induction motor
2464-776: Is a type of hydroelectric energy storage used by electric power systems for load balancing . A PSH system stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost surplus off-peak electric power is typically used to run the pumps. During periods of high electrical demand, the stored water is released through turbines to produce electric power. Pumped-storage hydroelectricity allows energy from intermittent sources (such as solar , wind , and other renewables) or excess electricity from continuous base-load sources (such as coal or nuclear) to be saved for periods of higher demand. The reservoirs used with pumped storage can be quite small, when contrasted with
2552-441: Is much smaller than the land occupied by the solar and windfarms that the storage might support. Closed loop (off-river) pumped hydro storage has the smallest carbon emissions per unit of storage of all candidates for large-scale energy storage. Pumped storage plants can operate with seawater, although there are additional challenges compared to using fresh water, such as saltwater corrosion and barnacle growth. Inaugurated in 1966,
2640-531: Is necessary. Smaller pumped storage plants cannot achieve the same economies of scale as larger ones, but some do exist, including a recent 13 MW project in Germany. Shell Energy has proposed a 5 MW project in Washington State. Some have proposed small pumped storage plants in buildings, although these are not yet economical. Also, it is difficult to fit large reservoirs into the urban landscape (and
2728-428: Is progressively replacing all locomotive-hauled slow and fast passenger and intercity trains with EMUs. The upgraded trains are re-branded as MEMUs. The system uses multiple electrical units operating on 25 kV AC drawn from overhead lines . The trailer coaches have two toilets for passengers and one for the crew. The train can run up to 200 km (120 mi) between Eastern Ghat and Western Ghat. The rakes have
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2816-640: Is rarely due to wind or solar power alone, increased use of such generation will increase the likelihood of those occurrences. It is particularly likely that pumped storage will become especially important as a balance for very large-scale photovoltaic and wind generation. Increased long-distance transmission capacity combined with significant amounts of energy storage will be a crucial part of regulating any large-scale deployment of intermittent renewable power sources. The high non-firm renewable electricity penetration in some regions supplies 40% of annual output, but 60% may be reached before additional storage
2904-940: Is somewhat mitigated by their proven long service life of decades - and in some cases over a century, which is three to five times longer than utility-scale batteries. When electricity prices become negative , pumped hydro operators may earn twice - when "buying" the electricity to pump the water to the upper reservoir at negative spot prices and again when selling the electricity at a later time when prices are high. Along with energy management, pumped storage systems help stabilize electrical network frequency and provide reserve generation. Thermal plants are much less able to respond to sudden changes in electrical demand that potentially cause frequency and voltage instability. Pumped storage plants, like other hydroelectric plants, can respond to load changes within seconds. The most important use for pumped storage has traditionally been to balance baseload powerplants, but they may also be used to abate
2992-477: Is variable speed machines for greater efficiency. These machines operate in synchronization with the network frequency when generating, but operate asynchronously (independent of the network frequency) when pumping. The first use of pumped-storage in the United States was in 1930 by the Connecticut Electric and Power Company, using a large reservoir located near New Milford, Connecticut, pumping water from
3080-471: The South Side Elevated Railroad , where it became popularly known as the " L ". Sprague's motor and related inventions led to an explosion of interest and use in electric motors for industry. The development of electric motors of acceptable efficiency was delayed for several decades by failure to recognize the extreme importance of an air gap between the rotor and stator. Efficient designs have
3168-529: The Titlagarh coach maintenance shops. Marathwada Rail Coach Factory, Latur is currently trying to ramp up production capacity of 250 MEMU coaches per annum. MEMU Car Sheds are functioning for the maintenance of MEMU rakes in most of the states where the services are operated. MEMU Car Sheds are operational in Avadi, Bangalore, Kollam , Palakkad, Tambaram, Trichy and Vijayawada under Southern Railway. New 3rd generation
3256-439: The armature . Two or more electrical contacts called brushes made of a soft conductive material like carbon press against the commutator. The brushes make sliding contact with successive commutator segments as the rotator turns, supplying current to the rotor. The windings on the rotor are connected to the commutator segments. The commutator reverses the current direction in the rotor windings with each half turn (180°), so
3344-416: The 1740s. The theoretical principle behind them, Coulomb's law , was discovered but not published, by Henry Cavendish in 1771. This law was discovered independently by Charles-Augustin de Coulomb in 1785, who published it so that it is now known by his name. Due to the difficulty of generating the high voltages they required, electrostatic motors were never used for practical purposes. The invention of
3432-614: The 240 MW Rance tidal power station in France can partially work as a pumped-storage station. When high tides occur at off-peak hours, the turbines can be used to pump more seawater into the reservoir than the high tide would have naturally brought in. It is the only large-scale power plant of its kind. In 1999, the 30 MW Yanbaru project in Okinawa was the first demonstration of seawater pumped storage. It has since been decommissioned. A 300 MW seawater-based Lanai Pumped Storage Project
3520-488: The 3 million abandoned wells in the US. Using hydraulic fracturing pressure can be stored underground in impermeable strata such as shale. The shale used contains no hydrocarbons. Small (or micro) applications for pumped storage could be built on streams and within infrastructures, such as drinking water networks and artificial snow-making infrastructures. In this regard, a storm-water basin has been concretely implemented as
3608-606: The EU. Japan had 25.5 GW net capacity (24.5% of world capacity). The six largest operational pumped-storage plants are listed below (for a detailed list see List of pumped-storage hydroelectric power stations ) : Australia has 15GW of pumped storage under construction or in development. Examples include: In June 2018 the Australian federal government announced that 14 sites had been identified in Tasmania for pumped storage hydro, with
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3696-503: The Housatonic River to the storage reservoir 70 metres (230 ft) above. In 2009, world pumped storage generating capacity was 104 GW , while other sources claim 127 GW, which comprises the vast majority of all types of utility grade electric storage. The European Union had 38.3 GW net capacity (36.8% of world capacity) out of a total of 140 GW of hydropower and representing 5% of total net electrical capacity in
3784-557: The Kidston project under construction in Australia. Water requirements for PSH are small: about 1 gigalitre of initial fill water per gigawatt-hour of storage. This water is recycled uphill and back downhill between the two reservoirs for many decades, but evaporation losses (beyond what rainfall and any inflow from local waterways provide) must be replaced. Land requirements are also small: about 10 hectares per gigawatt-hour of storage, which
3872-573: The Lauffen waterfall on the Neckar river. The Lauffen power station included a 240 kW 86 V 40 Hz alternator and a step-up transformer while at the exhibition a step-down transformer fed a 100-hp three-phase induction motor that powered an artificial waterfall, representing the transfer of the original power source. The three-phase induction is now used for the vast majority of commercial applications. Mikhail Dolivo-Dobrovolsky claimed that Tesla's motor
3960-449: The United States. As of late 2014, there were 51 active project proposals with a total of 39 GW of new nameplate capacity across all stages of the FERC licensing process for new pumped storage hydroelectric plants in the United States, but no new plants were currently under construction in the United States at the time. Conventional hydroelectric dams may also make use of pumped storage in
4048-520: The development of DC motors, but all encountered the same battery cost issues. As no electricity distribution system was available at the time, no practical commercial market emerged for these motors. After many other more or less successful attempts with relatively weak rotating and reciprocating apparatus Prussian/Russian Moritz von Jacobi created the first real rotating electric motor in May 1834. It developed remarkable mechanical output power. His motor set
4136-478: The developments by Zénobe Gramme who, in 1871, reinvented Pacinotti's design and adopted some solutions by Werner Siemens . A benefit to DC machines came from the discovery of the reversibility of the electric machine, which was announced by Siemens in 1867 and observed by Pacinotti in 1869. Gramme accidentally demonstrated it on the occasion of the 1873 Vienna World's Fair , when he connected two such DC devices up to 2 km from each other, using one of them as
4224-573: The effective storage in about 2 trillion electric vehicle batteries), which is about 100 times more than needed to support 100% renewable electricity. Most are closed-loop systems away from rivers. Areas of natural beauty and new dams on rivers can be avoided because of the very large number of potential sites. Some projects utilise existing reservoirs (dubbed "bluefield") such as the 350 Gigawatt-hour Snowy 2.0 scheme under construction in Australia. Some recently proposed projects propose to take advantage of "brownfield" locations such as disused mines such as
4312-640: The efficiency of pumped storage by using fluid 2.5x denser than water ("a fine-milled suspended solid in water" ), such that "projects can be 2.5x smaller for the same power." The first use of pumped storage was in 1907 in Switzerland , at the Engeweiher pumped storage facility near Schaffhausen, Switzerland. In the 1930s reversible hydroelectric turbines became available. This apparatus could operate both as turbine generators and in reverse as electric motor-driven pumps. The latest in large-scale engineering technology
4400-460: The electric energy produced in the US. In 1824, French physicist François Arago formulated the existence of rotating magnetic fields , termed Arago's rotations , which, by manually turning switches on and off, Walter Baily demonstrated in 1879 as in effect the first primitive induction motor . In the 1880s many inventors were trying to develop workable AC motors because AC's advantages in long-distance high-voltage transmission were offset by
4488-566: The electric grid, provided for electric distribution to trolleys via overhead wires and the trolley pole, and provided control systems for electric operations. This allowed Sprague to use electric motors to invent the first electric trolley system in 1887–88 in Richmond, Virginia , the electric elevator and control system in 1892, and the electric subway with independently powered centrally-controlled cars. The latter were first installed in 1892 in Chicago by
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#17328844584604576-470: The electrochemical battery by Alessandro Volta in 1799 made possible the production of persistent electric currents. Hans Christian Ørsted discovered in 1820 that an electric current creates a magnetic field, which can exert a force on a magnet. It only took a few weeks for André-Marie Ampère to develop the first formulation of the electromagnetic interaction and present the Ampère's force law , that described
4664-472: The first device to contain the three main components of practical DC motors: the stator , rotor and commutator. The device employed no permanent magnets, as the magnetic fields of both the stationary and revolving components were produced solely by the currents flowing through their windings. The first commutator DC electric motor capable of turning machinery was invented by English scientist William Sturgeon in 1832. Following Sturgeon's work,
4752-418: The fluctuating output of intermittent energy sources . Pumped storage provides a load at times of high electricity output and low electricity demand, enabling additional system peak capacity. In certain jurisdictions, electricity prices may be close to zero or occasionally negative on occasions that there is more electrical generation available than there is load available to absorb it. Although at present this
4840-402: The fluctuating water level may make them unsuitable for recreational use). Nevertheless, some authors defend the technological simplicity and security of water supply as important externalities . The main requirement for PSH is hilly country. The global greenfield pumped hydro atlas lists more than 800,000 potential sites around the world with combined storage of 86 million GWh (equivalent to
4928-435: The grid. The quantity of power created when water is let in, grows proportionally to the height of the column of water above the sphere. In other words: the deeper the sphere is located, the more densely it can store energy. As such, the energy storage capacity of the submerged reservoir is not governed by the gravitational energy in the traditional sense, but by the vertical pressure variation . RheEnergise aim to improve
5016-579: The inability to operate motors on AC. The first alternating-current commutatorless induction motor was invented by Galileo Ferraris in 1885. Ferraris was able to improve his first design by producing more advanced setups in 1886. In 1888, the Royal Academy of Science of Turin published Ferraris's research detailing the foundations of motor operation, while concluding at that time that "the apparatus based on that principle could not be of any commercial importance as motor." Possible industrial development
5104-415: The lakes of conventional hydroelectric plants of similar power capacity, and generating periods are often less than half a day. The round-trip efficiency of PSH varies between 70% and 80%. Although the losses of the pumping process make the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand , when electricity prices are highest. If
5192-689: The largest PHES in the world at 5 GW. China has the largest capacity of pumped-storage hydroelectricity in the world. In January 2019, the State Grid Corporation of China announced plans to invest US$ 5.7 billion in five pumped hydro storage plants with a total 6 GW capacity, to be located in Hebei, Jilin, Zhejiang, Shandong provinces, and in Xinjiang Autonomous Region. China is seeking to build 40 GW of pumped hydro capacity installed by 2020. There are 9 power stations capable of pumping with
5280-644: The load are exerted beyond the outermost bearing, the load is said to be overhung. The rotor is supported by bearings , which allow the rotor to turn on its axis by transferring the force of axial and radial loads from the shaft to the motor housing. A DC motor is usually supplied through a split ring commutator as described above. AC motors' commutation can be achieved using either a slip ring commutator or external commutation. It can be fixed-speed or variable-speed control type, and can be synchronous or asynchronous. Universal motors can run on either AC or DC. DC motors can be operated at variable speeds by adjusting
5368-538: The magnet, showing that the current gave rise to a close circular magnetic field around the wire. Faraday published the results of his discovery in the Quarterly Journal of Science , and sent copies of his paper along with pocket-sized models of his device to colleagues around the world so they could also witness the phenomenon of electromagnetic rotations. This motor is often demonstrated in physics experiments, substituting brine for (toxic) mercury. Barlow's wheel
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#17328844584605456-477: The number of underground pumped storage opportunities may increase if abandoned coal mines prove suitable. In Bendigo , Victoria, Australia, the Bendigo Sustainability Group has proposed the use of the old gold mines under Bendigo for Pumped Hydro Energy Storage. Bendigo has the greatest concentration of deep shaft hard rock mines anywhere in the world with over 5,000 shafts sunk under Bendigo in
5544-625: The operation point in pumping usually differs from the operation point in PAT mode. In closed-loop systems, pure pumped-storage plants store water in an upper reservoir with no natural inflows, while pump-back plants utilize a combination of pumped storage and conventional hydroelectric plants with an upper reservoir that is replenished in part by natural inflows from a stream or river. Plants that do not use pumped storage are referred to as conventional hydroelectric plants; conventional hydroelectric plants that have significant storage capacity may be able to play
5632-485: The point of use, and improving power transmission efficiency. Electric motors applied in agriculture eliminated human and animal muscle power from such tasks as handling grain or pumping water. Household uses (like in washing machines, dishwashers, fans, air conditioners and refrigerators (replacing ice boxes ) of electric motors reduced heavy labor in the home and made higher standards of convenience, comfort and safety possible. Today, electric motors consume more than half of
5720-476: The potential of adding 4.8GW to the national grid if a second interconnector beneath Bass Strait was constructed. The Snowy 2.0 project will link two existing dams in the New South Wales' Snowy Mountains to provide 2,000 MW of capacity and 350,000 MWh of storage. In September 2022, a pumped hydroelectric storage (PHES) scheme was announced at Pioneer-Burdekin in central Queensland that has the potential to be
5808-554: The power grid, permitting thermal power stations such as coal-fired plants and nuclear power plants that provide base-load electricity to continue operating at peak efficiency, while reducing the need for "peaking" power plants that use the same fuels as many base-load thermal plants, gas and oil, but have been designed for flexibility rather than maximal efficiency. Hence pumped storage systems are crucial when coordinating large groups of heterogeneous generators . Capital costs for pumped-storage plants are relatively high, although this
5896-477: The production of mechanical force by the interaction of an electric current and a magnetic field. Michael Faraday gave the first demonstration of the effect with a rotary motion on 3 September 1821 in the basement of the Royal Institution . A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet (PM) was placed. When a current was passed through the wire, the wire rotated around
5984-1041: The proposed Summit project in Norton, Ohio , the proposed Maysville project in Kentucky (underground limestone mine), and the Mount Hope project in New Jersey , which was to have used a former iron mine as the lower reservoir. The proposed energy storage at the Callio site in Pyhäjärvi ( Finland ) would utilize the deepest base metal mine in Europe, with 1,450 metres (4,760 ft) elevation difference. Several new underground pumped storage projects have been proposed. Cost-per-kilowatt estimates for these projects can be lower than for surface projects if they use existing underground mine space. There are limited opportunities involving suitable underground space, but
6072-428: The rotor and stator ferromagnetic cores have projections called poles that face each other. Wire is wound around each pole below the pole face, which become north or south poles when current flows through the wire. In a nonsalient-pole (distributed field or round-rotor) motor, the ferromagnetic core is a smooth cylinder, with the windings distributed evenly in slots around the circumference. Supplying alternating current in
6160-465: The rotor and the stator. The product between these two fields gives rise to a force and thus a torque on the motor shaft. One or both of these fields changes as the rotor turns. This is done by switching the poles on and off at the right time, or varying the strength of the pole. Motors can be designed to operate on DC current, on AC current, or some types can work on either. AC motors can be either asynchronous or synchronous. Synchronous motors require
6248-577: The rotor to turn at the same speed as the stator's rotating field. Asynchronous rotors relax this constraint. A fractional-horsepower motor either has a rating below about 1 horsepower (0.746 kW), or is manufactured with a frame size smaller than a standard 1 HP motor. Many household and industrial motors are in the fractional-horsepower class. excited: PM Ferromagnetic rotor: Two-phase (condenser) Single-phase: Pumped-storage hydroelectricity Pumped-storage hydroelectricity ( PSH ), or pumped hydroelectric energy storage ( PHES ),
6336-402: The rotor, which moves, and the stator, which does not. Electrically, the motor consists of two parts, the field magnets and the armature, one of which is attached to the rotor and the other to the stator. Together they form a magnetic circuit . The magnets create a magnetic field that passes through the armature. These can be electromagnets or permanent magnets . The field magnet is usually on
6424-619: The sea area replacing seawater by constructing coastal reservoirs . The stored river water is pumped to uplands by constructing a series of embankment canals and pumped storage hydroelectric stations for the purpose of energy storage, irrigation, industrial, municipal, rejuvenation of over exploited rivers, etc. These multipurpose coastal reservoir projects offer massive pumped-storage hydroelectric potential to utilize variable and intermittent solar and wind power that are carbon-neutral, clean, and renewable energy sources. The use of underground reservoirs has been investigated. Recent examples include
6512-430: The second half of the 19th Century. The deepest shaft extends 1,406 metres vertically underground. A recent pre-feasibility study has shown the concept to be viable with a generation capacity of 30 MW and a run time of 6 hours using a water head of over 750 metres. US-based start-up Quidnet Energy is exploring using abandoned oil and gas wells for pumped storage. If successful they hope to scale up, utilizing some of
6600-454: The stator and the armature on the rotor, but these may be reversed. The rotor is the moving part that delivers the mechanical power. The rotor typically holds conductors that carry currents, on which the magnetic field of the stator exerts force to turn the shaft. The stator surrounds the rotor, and usually holds field magnets, which are either electromagnets (wire windings around a ferromagnetic iron core) or permanent magnets . These create
6688-435: The stator in plastic resin to prevent corrosion and/or reduce conducted noise. An air gap between the stator and rotor allows it to turn. The width of the gap has a significant effect on the motor's electrical characteristics. It is generally made as small as possible, as a large gap weakens performance. Conversely, gaps that are too small may create friction in addition to noise. The armature consists of wire windings on
6776-406: The torque applied to the rotor is always in the same direction. Without this reversal, the direction of torque on each rotor winding would reverse with each half turn, stopping the rotor. Commutated motors have been mostly replaced by brushless motors , permanent magnet motors , and induction motors . The motor shaft extends outside of the motor, where it satisfies the load. Because the forces of
6864-424: The total installed capacity of small pumped-storage hydropower plants in 2011 could be increased by 3 to 9 times by providing adequate policy instruments . Using a pumped-storage system of cisterns and small generators, pico hydro may also be effective for "closed loop" home energy generation systems. In March 2017, the research project StEnSea (Storing Energy at Sea) announced their successful completion of
6952-421: The upper lake collects significant rainfall, or is fed by a river, then the plant may be a net energy producer in the manner of a traditional hydroelectric plant. Pumped storage is by far the largest-capacity form of grid energy storage available, and, as of 2020 , accounts for around 95% of all active storage installations worldwide, with a total installed throughput capacity of over 181 GW and as of 2020
7040-663: The voltage applied to the terminals or by using pulse-width modulation (PWM). AC motors operated at a fixed speed are generally powered directly from the grid or through motor soft starters . AC motors operated at variable speeds are powered with various power inverter , variable-frequency drive or electronic commutator technologies. The term electronic commutator is usually associated with self-commutated brushless DC motor and switched reluctance motor applications. Electric motors operate on one of three physical principles: magnetism , electrostatics and piezoelectricity . In magnetic motors, magnetic fields are formed in both
7128-406: The winding, further increasing the efficiency. In 1886, Frank Julian Sprague invented the first practical DC motor, a non-sparking device that maintained relatively constant speed under variable loads. Other Sprague electric inventions about this time greatly improved grid electric distribution (prior work done while employed by Thomas Edison ), allowed power from electric motors to be returned to
7216-431: The windings creates poles in the core that rotate continuously. A shaded-pole motor has a winding around part of the pole that delays the phase of the magnetic field for that pole. A commutator is a rotary electrical switch that supplies current to the rotor. It periodically reverses the flow of current in the rotor windings as the shaft rotates. It consists of a cylinder composed of multiple metal contact segments on
7304-508: Was an early refinement to this Faraday demonstration, although these and similar homopolar motors remained unsuited to practical application until late in the century. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils . After Jedlik solved the technical problems of continuous rotation with the invention of the commutator , he called his early devices "electromagnetic self-rotors". Although they were used only for teaching, in 1828 Jedlik demonstrated
7392-512: Was considered for Lanai, Hawaii, and seawater-based projects have been proposed in Ireland. A pair of proposed projects in the Atacama Desert in northern Chile would use 600 MW of photovoltaic solar (Skies of Tarapacá) together with 300 MW of pumped storage (Mirror of Tarapacá) lifting seawater 600 metres (2,000 ft) up a coastal cliff. Freshwater from the river floods is stored in
7480-445: Was envisioned by Nikola Tesla , who invented independently his induction motor in 1887 and obtained a patent in May 1888. In the same year, Tesla presented his paper A New System of Alternate Current Motors and Transformers to the AIEE that described three patented two-phase four-stator-pole motor types: one with a four-pole rotor forming a non-self-starting reluctance motor , another with
7568-453: Was found not to be suitable for street cars, but Westinghouse engineers successfully adapted it to power a mining operation in Telluride, Colorado in 1891. Westinghouse achieved its first practical induction motor in 1892 and developed a line of polyphase 60 hertz induction motors in 1893, but these early Westinghouse motors were two-phase motors with wound rotors. B.G. Lamme later developed
7656-438: Was not practical because of two-phase pulsations, which prompted him to persist in his three-phase work. 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 . Induction motor improvements flowing from these inventions and innovations were such that
7744-451: Was rolled out from RCF Kapurthala with following features: MEMU uses 8,12 and 14 car coaches. The trailer coaches have two toilets for passengers and one for the crew. This train can go either fast or slow. Electric motor An electric motor is a machine that converts electrical energy into mechanical energy . Most electric motors operate through the interaction between the motor's magnetic field and electric current in
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