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69-663: The power plant has four Francis turbines with a combined capacity of 120 MW. Each turbine weighs 60,000 pounds (27,000 kg). The head is 72 feet (21.9 m). It produces electricity at 97 percent efficiency. Half of the electricity the plant produces is used by the Metropolitan Water District to pump water along the Colorado River Aqueduct , and the rest is sold to utilities in California, Arizona and Nevada. The generation of power

138-459: A generator is a device that converts motion-based power ( potential and kinetic energy ) or fuel-based power ( chemical energy ) into electric power for use in an external circuit . Sources of mechanical energy include steam turbines , gas turbines , water turbines , internal combustion engines , wind turbines and even hand cranks . The first electromagnetic generator, the Faraday disk ,

207-653: A steam power plant . The first practical design was the AVCO Mk. 25, developed in 1965. The U.S. government funded substantial development, culminating in a 25 MW demonstration plant in 1987. In the Soviet Union from 1972 until the late 1980s, the MHD plant U 25 was in regular utility operation on the Moscow power system with a rating of 25 MW, the largest MHD plant rating in the world at that time. MHD generators operated as

276-698: A topping cycle are currently (2007) less efficient than combined cycle gas turbines . Induction AC motors may be used as generators, turning mechanical energy into electric current. Induction generators operate by mechanically turning their rotor faster than the simultaneous speed, giving negative slip. A regular AC non-simultaneous motor usually can be used as a generator, without any changes to its parts. Induction generators are useful in applications like minihydro power plants, wind turbines, or in reducing high-pressure gas streams to lower pressure, because they can recover energy with relatively simple controls. They do not require another circuit to start working because

345-559: A 1963 Supreme Court decision settled the issue. The court has had to adjust the agreement several times since, most recently in 2000. As recently as 2008 Arizona Senator John McCain called for a renegotiation of the plan. In 1935, when Arizona Governor Benjamin Baker Moeur sent 6 members of the Arizona National Guard to observe the dam's construction, they reported back that there was construction activity on

414-479: A British electrician, J. E. H. Gordon , in 1882. The first public demonstration of an "alternator system" was given by William Stanley Jr. , an employee of Westinghouse Electric in 1886. Sebastian Ziani de Ferranti established Ferranti, Thompson and Ince in 1882, to market his Ferranti-Thompson Alternator , invented with the help of renowned physicist Lord Kelvin . His early alternators produced frequencies between 100 and 300 Hz . Ferranti went on to design

483-436: A foot pump, such generators can be practically used to charge batteries, and in some cases are designed with an integral inverter. An average "healthy human" can produce a steady 75 watts (0.1 horsepower) for a full eight hour period, while a "first class athlete" can produce approximately 298 watts (0.4 horsepower) for a similar period, at the end of which an undetermined period of rest and recovery will be required. At 298 watts,

552-456: A generator and load is shown in the adjacent diagram. The generator is represented by an abstract generator consisting of an ideal voltage source and an internal impedance. The generator's V G {\displaystyle V_{\text{G}}} and R G {\displaystyle R_{\text{G}}} parameters can be determined by measuring the winding resistance (corrected to operating temperature ), and measuring

621-430: A generator consists of a rotating part and a stationary part which together form a magnetic circuit : One of these parts generates a magnetic field, the other has a wire winding in which the changing field induces an electric current: The armature can be on either the rotor or the stator, depending on the design, with the field coil or magnet on the other part. Before the connection between magnetism and electricity

690-449: A magnetic field produces a current which changes direction with each 180° rotation, an alternating current (AC). However many early uses of electricity required direct current (DC). In the first practical electric generators, called dynamos , the AC was converted into DC with a commutator , a set of rotating switch contacts on the armature shaft. The commutator reversed the connection of

759-403: A million amperes , because the homopolar generator can be made to have very low internal resistance. A magnetohydrodynamic generator directly extracts electric power from moving hot gases through a magnetic field, without the use of rotating electromagnetic machinery. MHD generators were originally developed because the output of a plasma MHD generator is a flame, well able to heat the boilers of

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828-534: A reservoir is filled by the turbine (acting as a pump) driven by the generator acting as a large electrical motor during periods of low power demand, and then reversed and used to generate power during peak demand. These pump storage reservoirs act as large energy storage sources to store "excess" electrical energy in the form of water in elevated reservoirs. This is one of a few methods that allow temporary excess electrical capacity to be stored for later utilization. Electric generator In electricity generation ,

897-488: A series of discoveries, the dynamo was succeeded by many later inventions, especially the AC alternator , which was capable of generating alternating current . It is commonly known to be the Synchronous Generators (SGs). The synchronous machines are directly connected to the grid and need to be properly synchronized during startup. Moreover, they are excited with special control to enhance the stability of

966-438: A sliding magnet moves back and forth through a solenoid , a copper wire or a coil. An alternating current is induced in the wire, or loops of wire, by Faraday's law of induction each time the magnet slides through. This type of generator is used in the Faraday flashlight . Larger linear electricity generators are used in wave power schemes. Grid-connected generators deliver power at a constant frequency. For generators of

1035-434: A small DC voltage . This design was inefficient, due to self-cancelling counterflows of current in regions of the disk that were not under the influence of the magnetic field. While current was induced directly underneath the magnet, the current would circulate backwards in regions that were outside the influence of the magnetic field. This counterflow limited the power output to the pickup wires and induced waste heating of

1104-450: A stable power supply. Electric scooters with regenerative braking have become popular all over the world. Engineers use kinetic energy recovery systems on the scooter to reduce energy consumption and increase its range up to 40-60% by simply recovering energy using the magnetic brake, which generates electric energy for further use. Modern vehicles reach speed up to 25–30 km/h and can run up to 35–40 km. An engine-generator

1173-417: A water- or wind-powered generator to trickle-charge the batteries. A small propeller , wind turbine or turbine is connected to a low-power generator to supply currents at typical wind or cruising speeds. Recreational vehicles need an extra power supply to power their onboard accessories, including air conditioning units, and refrigerators. An RV power plug is connected to the electric generator to obtain

1242-436: A wide range of heads and flows. This versatility, along with their high efficiency, has made them the most widely used turbine in the world. Francis type units cover a head range from 40 to 600 m (130 to 2,000 ft), and their connected generator output power varies from just a few kilowatts up to 1000 MW. Large Francis turbines are individually designed for each site to operate with the given water flow and water head at

1311-404: Is a type of reaction turbine, a category of turbine in which the working fluid comes to the turbine under immense pressure and the energy is extracted by the turbine blades from the working fluid. A part of the energy is given up by the fluid because of pressure changes occurring on the blades of the turbine, quantified by the expression of degree of reaction , while the remaining part of the energy

1380-562: Is an industrial facility that generates electricity . Most power stations contain one or more generators, or spinning machines converting mechanical power into three-phase electrical power . The relative motion between a magnetic field and a conductor creates an electric current . The energy source harnessed to turn the generator varies widely. Most power stations in the world burn fossil fuels such as coal , oil , and natural gas to generate electricity. Cleaner sources include nuclear power , and increasingly use renewables such as

1449-432: Is between 100–300 metres (330–980 ft). Penstock diameters are between 1 and 10 m (3.3 and 32.8 ft). The speeds of different turbine units range from 70 to 1000  rpm . A wicket gate around the outside of the turbine's rotating runner controls the rate of water flow through the turbine for different power production rates. Francis turbines are usually mounted with a vertical shaft, to isolate water from

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1518-476: Is equal to that at the inlet to the draft tube. Using the Euler turbine equation, E / m = e = V w1 U 1 , where e is the energy transfer to the rotor per unit mass of the fluid. From the inlet velocity triangle, and Therefore The loss of kinetic energy per unit mass at the outlet is V f2 /2 . Therefore, neglecting friction, the blade efficiency becomes i.e. Degree of reaction can be defined as

1587-445: Is extracted by the volute casing of the turbine. At the exit, water acts on the spinning cup-shaped runner features, leaving at low velocity and low swirl with very little kinetic or potential energy left. The turbine's exit tube is shaped to help decelerate the water flow and recover the pressure. Usually the flow velocity (velocity perpendicular to the tangential direction) remains constant throughout, i.e. V f1 = V f2 and

1656-668: Is limited by a requirement to keep the water level of Lake Havasu between 440 and 450 feet (134.1 and 137.2 meters) above sea level for proper operation of pumping plants for the Central Arizona Project and the Colorado River Aqueduct. Lake Havasu is the water source for the Colorado River Aqueduct . The aqueduct is operated by the Metropolitan Water District of Southern California , which supplies water to almost all cities in

1725-455: Is necessary, as these are major parameters affecting power production. Draft tube : The draft tube is a conduit that connects the runner exit to the tail race where the water is discharged from the turbine. Its primary function is to reduce the velocity of discharged water to minimize the loss of kinetic energy at the outlet. This permits the turbine to be set above the tail water without appreciable drop of available head. The Francis turbine

1794-497: Is provided by one or more electromagnets, which are usually called field coils. Large power generation dynamos are now rarely seen due to the now nearly universal use of alternating current for power distribution. Before the adoption of AC, very large direct-current dynamos were the only means of power generation and distribution. AC has come to dominate due to the ability of AC to be easily transformed to and from very high voltages to permit low losses over large distances. Through

1863-415: Is self- excited , i.e. its field electromagnets are powered by the machine's own output. Other types of DC generators use a separate source of direct current to energise their field magnets. A homopolar generator is a DC electrical generator comprising an electrically conductive disc or cylinder rotating in a plane perpendicular to a uniform static magnetic field. A potential difference is created between

1932-405: Is the ability to independently supply electricity, allowing the units to serve as backup power sources. A generator can also be driven by human muscle power (for instance, in field radio station equipment). Human powered electric generators are commercially available, and have been the project of some DIY enthusiasts. Typically operated by means of pedal power, a converted bicycle trainer, or

2001-485: Is the combination of an electrical generator and an engine ( prime mover ) mounted together to form a single piece of self-contained equipment. The engines used are usually piston engines, but gas turbines can also be used, and there are even hybrid diesel-gas units, called dual-fuel units. Many different versions of engine-generators are available – ranging from very small portable petrol powered sets to large turbine installations. The primary advantage of engine-generators

2070-805: The Deptford Power Station for the London Electric Supply Corporation in 1887 using an alternating current system. On its completion in 1891, it was the first truly modern power station, supplying high-voltage AC power that was then "stepped down" for consumer use on each street. This basic system remains in use today around the world. After 1891, polyphase alternators were introduced to supply currents of multiple differing phases. Later alternators were designed for varying alternating-current frequencies between sixteen and about one hundred hertz, for use with arc lighting, incandescent lighting and electric motors. As

2139-671: The Air ), medical and other needs in remote stations and towns. A tachogenerator is an electromechanical device which produces an output voltage proportional to its shaft speed. It may be used for a speed indicator or in a feedback speed control system. Tachogenerators are frequently used to power tachometers to measure the speeds of electric motors, engines, and the equipment they power. Generators generate voltage roughly proportional to shaft speed. With precise construction and design, generators can be built to produce very precise voltages for certain ranges of shaft speeds. An equivalent circuit of

Parker Dam - Misplaced Pages Continue

2208-531: The Arizona side of the river. Arizona Attorney General Arthur La Prade concluded that the Metropolitan Water District had no right to build on Arizona's territory, which prompted Governor Moeur to send a larger National Guard force to halt construction. The troops were recalled when Secretary of the Interior Harold L. Ickes halted construction until the issue had been settled. The Department of

2277-462: The Francis turbine around 1920, being named after British-American engineer James B. Francis who in 1848 created a new turbine design. Francis turbines are primarily used for producing electricity. The power output of the electric generators generally ranges from just a few kilowatts up to 1000 MW, though mini-hydro installations may be lower. The best performance is seen when the head height

2346-585: The Interior took Arizona to court over the issue hoping to end the state's interference. To the Department of the Interior's surprise, the Supreme Court sided with Arizona and dismissed the injunction. The court concluded that the dam had never been directly approved by Congress and that California was not entitled to build on Arizona's land without Arizona's consent. Arizona eventually agreed to allow

2415-478: The armature winding to the circuit every 180° rotation of the shaft, creating a pulsing DC current. One of the first dynamos was built by Hippolyte Pixii in 1832. The dynamo was the first electrical generator capable of delivering power for industry. The Woolrich Electrical Generator of 1844, now in Thinktank, Birmingham Science Museum , is the earliest electrical generator used in an industrial process. It

2484-436: The armature winding. When the generator first starts to turn, the small amount of remanent magnetism present in the iron core provides a magnetic field to get it started, generating a small current in the armature. This flows through the field coils, creating a larger magnetic field which generates a larger armature current. This "bootstrap" process continues until the magnetic field in the core levels off due to saturation and

2553-402: The assistance of power electronic devices, these can regulate the output frequency to a desired value over a wider range of generator shaft speeds. Alternatively, a standard generator can be used with no attempt to regulate frequency, and the resulting power converted to the desired output frequency with a rectifier and converter combination. Allowing a wider range of prime mover speeds can improve

2622-464: The average "healthy human" becomes exhausted within 10 minutes. The net electrical power that can be produced will be less, due to the efficiency of the generator. Portable radio receivers with a crank are made to reduce battery purchase requirements, see clockwork radio . During the mid 20th century, pedal powered radios were used throughout the Australian outback , to provide schooling ( School of

2691-409: The bicycle's tire on an as-needed basis, and hub dynamos which are directly attached to the bicycle's drive train. The name is conventional as they are small permanent-magnet alternators, not self-excited DC machines as are dynamos . Some electric bicycles are capable of regenerative braking , where the drive motor is used as a generator to recover some energy during braking. Sailing boats may use

2760-597: The center of the disc and the rim (or ends of the cylinder), the electrical polarity depending on the direction of rotation and the orientation of the field. It is also known as a unipolar generator , acyclic generator , disk dynamo , or Faraday disc . The voltage is typically low, on the order of a few volts in the case of small demonstration models, but large research generators can produce hundreds of volts, and some systems have multiple generators in series to produce an even larger voltage. They are unusual in that they can produce tremendous electric current, some more than

2829-436: The copper disc. Later homopolar generators would solve this problem by using an array of magnets arranged around the disc perimeter to maintain a steady field effect in one current-flow direction. Another disadvantage was that the output voltage was very low, due to the single current path through the magnetic flux. Experimenters found that using multiple turns of wire in a coil could produce higher, more useful voltages. Since

Parker Dam - Misplaced Pages Continue

2898-523: The dam in exchange for approval of the Gila River irrigation project. Francis turbine The Francis turbine is a type of water turbine . It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The process of arriving at the modern Francis runner design took from 1848 to approximately 1920. It became known as

2967-406: The design of high-efficiency turbines to precisely match a site's water flow and pressure ( water head ). A Francis turbine consists of the following main parts: Spiral casing : The spiral casing around the runner of the turbine is known as the volute casing or scroll case. Throughout its length, it has numerous openings at regular intervals to allow the working fluid to impinge on the blades of

3036-407: The difficulty of insulating machines that produced very high voltages, electrostatic generators had low power ratings, and were never used for generation of commercially significant quantities of electric power. Their only practical applications were to power early X-ray tubes , and later in some atomic particle accelerators . The operating principle of electromagnetic generators was discovered in

3105-413: The first major industrial uses of electricity. For example, in the 1870s Siemens used electromagnetic dynamos to power electric arc furnaces for the production of metals and other materials. The dynamo machine that was developed consisted of a stationary structure, which provides the magnetic field, and a set of rotating windings which turn within that field. On larger machines the constant magnetic field

3174-476: The generator reaches a steady state power output. Very large power station generators often utilize a separate smaller generator to excite the field coils of the larger. In the event of a severe widespread power outage where islanding of power stations has occurred, the stations may need to perform a black start to excite the fields of their largest generators, in order to restore customer power service. A dynamo uses commutators to produce direct current. It

3243-449: The generator. This also facilitates installation and maintenance. Water wheels of different types have been used for more than 1,000 years to power mills of all types, but they were relatively inefficient. Nineteenth-century efficiency improvements of water turbines allowed them to replace nearly all water wheel applications and compete with steam engines wherever water power was available. After electric generators were developed in

3312-505: The greater Los Angeles, San Bernardino, and San Diego areas. The district paid for nearly the entire cost of the dam, but it is owned and operated by the U.S. Bureau of Reclamation . Lake Havasu is also the water source for the Central Arizona Project Aqueduct (CAP). The project is designed to provide water for irrigated agricultural areas, as well as municipal water for several Arizona communities, including

3381-436: The guide and stay vanes is to convert the pressure energy of the fluid into kinetic energy. It also serves to direct the flow at design angles to the runner blades. Runner blades : Runner blades are the heart of any turbine. These are the centers where the fluid strikes and the tangential force of the impact produces torque causing the shaft of the turbine to rotate. Close attention to design of blade angles at inlet and outlet

3450-460: The highest possible efficiency, typically over 90% (to 99% ). In contrast to the Pelton turbine , the Francis turbine operates at its best completely filled with water at all times. The turbine and the outlet channel may be placed lower than the lake or sea level outside, reducing the tendency for cavitation . In addition to electrical production , they may also be used for pumped storage , where

3519-459: The late 1800s, turbines were a natural source of generator power where potential hydropower sources existed. In 1826 the French engineer Benoit Fourneyron developed a high-efficiency (80%) outward-flow water turbine. Water was directed tangentially through the turbine runner, causing it to spin. Another French engineer, Jean-Victor Poncelet , designed an inward-flow turbine in about 1820 that used

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3588-461: The metropolitan areas of Phoenix and Tucson . Construction of the dam was a contentious issue for Arizona. Built as part of the larger Colorado River Compact of 1922, several political groups, their members and privately owned utility companies in Arizona were not pleased with the plan in general and refused to sign it until 1944. Even then Arizona continued to dispute its water allotments until

3657-413: The output voltage is proportional to the number of turns, generators could be easily designed to produce any desired voltage by varying the number of turns. Wire windings became a basic feature of all subsequent generator designs. Independently of Faraday, Ányos Jedlik started experimenting in 1827 with the electromagnetic rotating devices which he called electromagnetic self-rotors . In the prototype of

3726-443: The overall energy production of an installation, at the cost of more complex generators and controls. For example, where a wind turbine operating at fixed frequency might be required to spill energy at high wind speeds, a variable speed system can allow recovery of energy contained during periods of high wind speed. A power station , also known as a power plant or powerhouse and sometimes generating station or generating plant ,

3795-472: The power system. Alternating current generating systems were known in simple forms from Michael Faraday 's original discovery of the magnetic induction of electric current . Faraday himself built an early alternator. His machine was a "rotating rectangle", whose operation was heteropolar : each active conductor passed successively through regions where the magnetic field was in opposite directions. Large two-phase alternating current generators were built by

3864-433: The ratio of pressure energy change in the blades to total energy change of the fluid. This means that it is a ratio indicating the fraction of total change in fluid pressure energy occurring in the blades of the turbine. The rest of the changes occur in the stator blades of the turbines and the volute casing as it has a varying cross-sectional area. For example, if the degree of reaction is given as 50%, that means that half of

3933-399: The requirements for larger scale power generation increased, a new limitation rose: the magnetic fields available from permanent magnets. Diverting a small amount of the power generated by the generator to an electromagnetic field coil allowed the generator to produce substantially more power. This concept was dubbed self-excitation . The field coils are connected in series or parallel with

4002-400: The runner. These openings convert the pressure energy of the fluid into kinetic energy just before the fluid impinges on the blades. This maintains a constant velocity despite the fact that numerous openings have been provided for the fluid to enter the blades, as the cross-sectional area of this casing decreases uniformly along the circumference. Guide and stay vanes : The primary function of

4071-606: The same principles. S. B. Howd obtained a US patent in 1838 for a similar design. In 1848 James B. Francis , while working as head engineer of the Locks and Canals company in the water wheel-powered textile factory city of Lowell, Massachusetts , improved on these designs to create more efficient turbines. He applied scientific principles and testing methods to produce a very efficient turbine design. More importantly, his mathematical and graphical calculation methods improved turbine design and engineering. His analytical methods allowed

4140-449: The single-pole electric starter (finished between 1852 and 1854) both the stationary and the revolving parts were electromagnetic. It was also the discovery of the principle of dynamo self-excitation , which replaced permanent magnet designs. He also may have formulated the concept of the dynamo in 1861 (before Siemens and Wheatstone ) but did not patent it as he thought he was not the first to realize this. A coil of wire rotating in

4209-521: The stator field. Wheatstone's design was similar to Siemens', with the difference that in the Siemens design the stator electromagnets were in series with the rotor, but in Wheatstone's design they were in parallel. The use of electromagnets rather than permanent magnets greatly increased the power output of a dynamo and enabled high power generation for the first time. This invention led directly to

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4278-611: The sun , wind , waves and running water . Motor vehicles require electrical energy to power their instrumentation, keep the engine itself operating, and recharge their batteries. Until about the 1960s motor vehicles tended to use DC generators (dynamos) with electromechanical regulators. Following the historical trend above and for many of the same reasons, these have now been replaced by alternators with built-in rectifier circuits. Bicycles require energy to power running lights and other equipment. There are two common kinds of generator in use on bicycles: bottle dynamos which engage

4347-476: The synchronous or induction type, the primer mover speed turning the generator shaft must be at a particular speed (or narrow range of speed) to deliver power at the required utility frequency. Mechanical speed-regulating devices may waste a significant fraction of the input energy to maintain a required fixed frequency. Where it is impractical or undesired to tightly regulate the speed of the prime mover, doubly fed electric machines may be used as generators. With

4416-883: The total energy change of the fluid is taking place in the rotor blades and the other half is occurring in the stator blades. If the degree of reaction is zero it means that the energy changes due to the rotor blades is zero, leading to a different turbine design called the Pelton Turbine . The second equality above holds, since discharge is radial in a Francis turbine. Now, putting in the value of 'e' from above and using V 1 2 − V f 2 2 = V f 1 2 cot ⁡ α 2 {\displaystyle V_{1}^{2}-V_{f2}^{2}=V_{f1}^{2}\cot \alpha _{2}} (as V f 2 = V f 1 {\displaystyle V_{f2}=V_{f1}} ) Francis turbines may be designed for

4485-421: The turning magnetic field is provided by induction from the one they have. They also do not require speed governor equipment as they inherently operate at the connected grid frequency. An induction generator must be powered with a leading voltage; this is usually done by connection to an electrical grid, or by powering themselves with phase correcting capacitors. In the simplest form of linear electric generator,

4554-409: The years of 1831–1832 by Michael Faraday . The principle, later called Faraday's law , is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux . Faraday also built the first electromagnetic generator, called the Faraday disk ; a type of homopolar generator , using a copper disc rotating between the poles of a horseshoe magnet . It produced

4623-429: Was discovered, electrostatic generators were invented. They operated on electrostatic principles, by using moving electrically charged belts, plates and disks that carried charge to a high potential electrode. The charge was generated using either of two mechanisms: electrostatic induction or the triboelectric effect . Such generators generated very high voltage and low current . Because of their inefficiency and

4692-635: Was invented in 1831 by British scientist Michael Faraday . Generators provide nearly all the power for electrical grids . In addition to electricity- and motion-based designs, photovoltaic and fuel cell powered generators use solar power and hydrogen-based fuels, respectively, to generate electrical output. The reverse conversion of electrical energy into mechanical energy is done by an electric motor , and motors and generators are very similar. Many motors can generate electricity from mechanical energy. Electromagnetic generators fall into one of two broad categories, dynamos and alternators. Mechanically,

4761-597: Was used by the firm of Elkingtons for commercial electroplating . The modern dynamo, fit for use in industrial applications, was invented independently by Sir Charles Wheatstone , Werner von Siemens and Samuel Alfred Varley . Varley took out a patent on 24 December 1866, while Siemens and Wheatstone both announced their discoveries on 17 January 1867 by delivering papers at the Royal Society . The "dynamo-electric machine" employed self-powering electromagnetic field coils rather than permanent magnets to create

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