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AC Motor
An AC motor is an electric motor driven by an alternating current (AC). The AC motor commonly consists of two basic parts, an outside stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft producing a second rotating magnetic field. The rotor magnetic field may be produced by permanent magnets, reluctance saliency, or DC or AC electrical windings. Less common, AC linear motors operate on similar principles as rotating motors but have their stationary and moving parts arranged in a straight line configuration, producing linear motion instead of rotation. Operating principles The two main types of AC motors are induction motors and synchronous motors. The induction motor (or asynchronous motor) always relies on a small difference in speed between the stator rotating magnetic field and the rotor shaft speed called slip to induce rotor current in the rotor AC winding. As a result, the induction mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, and are created by electric currents such as those used in electromagnets, and by electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function assigning a vector to each point of space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Life Of Nikola Tesla
''The'' () is a grammatical article in English, denoting persons or things already mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The'' is the most frequently used word in the English language; studies and analyses of texts have found it to account for seven percent of all printed English-language words. It is derived from gendered articles in Old English which combined in Middle English and now has a single form used with pronouns of any gender. The word can be used with both singular and plural nouns, and with a noun that starts with any letter. This is different from many other languages, which have different forms of the definite article for different genders or numbers. Pronunciation In most dialects, "the" is pronounced as (with the voiced dental fricative followed by a schwa) when followed by a consonant sound, and as (homophone of pronoun ''thee'') when followed by a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galileo Ferraris
Galileo Ferraris (31 October 1847 – 7 February 1897) was an Italian university professor, physicist and electrical engineer, one of the pioneers of AC power system and inventor of the induction motor although he never patented his work. Many newspapers touted that his work on the induction motor and power transmission systems were some of the greatest inventions of all ages. He published an extensive and complete monograph on the experimental results obtained with open-circuit transformers of the type designed by the power engineers Lucien Gaulard and John Dixon Gibbs. Biography Born at Livorno Vercellese (Kingdom of Sardinia), Ferraris gained a master's degree in engineering and became an assistant of technical physics near the Regal Italian Industrial Museum. Ferraris independently researched the rotary magnetic field in 1885. Ferraris experimented with different types of asynchronous electric motors. The research and his studies resulted in the development of an alt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wattmeter
The wattmeter is an instrument for measuring the electric active power (or the average of the rate of flow of electrical energy) in watts of any given circuit. Electromagnetic wattmeters are used for measurement of utility frequency and audio frequency power; other types are required for radio frequency measurements. A wattmeter reads the average value of the product ''v(t)i(t) = p(t)'', where ''v(t)'' is the voltage with positive reference polarity at the ± terminal with respect to the other terminal of the potential coil, and ''i(t)'' is the current with reference direction flowing into the ± terminal of the current coil. The wattmeter reads ''P = (1/T) ∫0T v(t)i(t) dt'', which in sinusoidal steady-state reduces to ''V''rms ''I''rms cos(φ), where ''T'' is the period of ''p(t)'' and φ is the angle by which the current lags the voltage. History On 14 August 1888, Oliver B. Shallenberge patented a watt-hour meter. The Hungarian Ottó Bláthy patented his AC wattmeter. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elihu Thomson
Elihu Thomson (March 29, 1853 – March 13, 1937) was an English-born American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France. Early life He was born in Manchester, England, on March 29, 1853, but his family moved to Philadelphia in the United States in 1858. and Thomson attended Central High School in Philadelphia and graduated in 1870. Thomson took a teaching position at Central, and in 1876, at the age of twenty-three, held the chair of Chemistry. In 1880, he left Central to pursue research in the emerging field of electrical engineering. Electrical innovations With Edwin J. Houston, a former teacher and later colleague of Thomson's at Central High School, Thomson founded the Thomson-Houston Electric Company. Notable inventions created by Thomson during this period include an arc-lighting system, an automatically regulated three-coil dynamo, a magnetic lightning arrester, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marcel Deprez
Marcel Deprez (12 December 1843 – 13 October 1918) was a French electrical engineer. He was born in Aillant-sur-Milleron. He died in Vincennes. Biography Deprez was born in Aillant-sur-Milleron in rural France and attended the School of Mines in Paris. He was not able to complete the course; however, he must have made a good impression, as he was employed as a secretary to the Director of the school, Charles Combes.The Engine Indicator , John Walters, Chapter 8, p.8-20 At , from 1876 to 1886, Deprez conducted the first experiments to transmit over long distances. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commutator (electric)
A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine. Two or more electrical contacts called "brushes" made of a soft conductive material like carbon press against the commutator, making sliding contact with successive segments of the commutator as it rotates. The windings (coils of wire) on the armature are connected to the commutator segments. Commutators are used in direct current (DC) machines: dynamos (DC generators) and many DC motors as well as universal motors. In a motor the commutator applies electric current to the windings. By reversing the current direction in the rotating windings each half turn, a steady rotating force (torque) is produced. In a generator the commutator picks off the current generated in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphase System
A polyphase system is a means of distributing alternating-current (AC) electrical power where the power transfer is constant during each electrical cycle. AC phase refers to the phase offset value (in degrees) between AC in multiple conducting wires; ''phases'' may also refer to the corresponding terminals and conductors, as in color codes. Polyphase systems have three or more energized electrical conductors carrying alternating currents with a defined phase between the voltage waves in each conductor; for three-phase voltage, the phase angle is 120° or 2π/3 radians (although early systems used 4 wire two-phase). Polyphase systems are particularly useful for transmitting power to electric motors which rely on alternating current to rotate. The most common example is the three-phase power system used for industrial applications and for power transmission. Compared to a single-phase, two-wire system, a three-phase three-wire system transmits three times as much power for t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Voltage
High voltage electricity refers to electrical potential large enough to cause injury or damage. In certain industries, ''high voltage'' refers to voltage above a certain threshold. Equipment and conductors that carry high voltage warrant special safety requirements and procedures. High voltage is used in electrical power distribution, in cathode ray tubes, to generate X-rays and particle beams, to produce electrical arcs, for ignition, in photomultiplier tubes, and in high-power amplifier vacuum tubes, as well as other industrial, military and scientific applications. Definition The numerical definition of depends on context. Two factors considered in classifying a voltage as high voltage are the possibility of causing a spark in air, and the danger of electric shock by contact or proximity. The International Electrotechnical Commission and its national counterparts ( IET, IEEE, VDE, etc.) define ''high voltage'' as above 1000 V for alternating current, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternator
An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.Gordon R. Selmon, ''Magnetoelectric Devices'', John Wiley and Sons, 1966 no ISBN pp. 391-393 Occasionally, a linear alternator or a rotating armature with a stationary magnetic field is used. In principle, any AC electrical generator can be called an alternator, but usually the term refers to small rotating machines driven by automotive and other internal combustion engines. An alternator that uses a permanent magnet for its magnetic field is called a magneto. Alternators in power stations driven by steam turbines are called turbo-alternators. Large 50 or 60 Hz three-phase alternators in power plants generate most of the world's electric power, which is distributed by electric power grids. History Alternating current generating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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