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Synchronization (alternating Current)
In an alternating current (AC) electric power system, synchronization is the process of matching the frequency, phase and voltage of a generator or other source to an electrical grid in order to transfer power. If two unconnected segments of a grid are to be connected to each other, they cannot safely exchange AC power until they are synchronized. A direct current (DC) generator can be connected to a power network simply by adjusting its open-circuit terminal voltage to match the network's voltage, by either adjusting its speed or its field excitation. The exact engine speed is not critical. However, an AC generator must additionally match its timing (frequency and phase) to the network voltage, which requires both speed and excitation to be systematically controlled for synchronization. This extra complexity was one of the arguments against AC operation during the war of currents in the 1880s. In modern grids, synchronization of generators is carried out by automatic systems. C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternating Current
Alternating current (AC) is an electric current that periodically reverses direction and changes its magnitude continuously with time, in contrast to direct current (DC), which flows only in one direction. Alternating current is the form in which electric power is delivered to businesses and residences, and it is the form of electrical energy that consumers typically use when they plug kitchen appliances, televisions, Fan (machine), fans and electric lamps into a wall socket. The abbreviations ''AC'' and ''DC'' are often used to mean simply ''alternating'' and ''direct'', respectively, as when they modify ''Electric current, current'' or ''voltage''. The usual waveform of alternating current in most electric power circuits is a sine wave, whose positive half-period corresponds with positive direction of the current and vice versa (the full period is called a ''wave cycle, cycle''). "Alternating current" most commonly refers to power distribution, but a wide range of other appl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steam Turbine
A steam turbine or steam turbine engine is a machine or heat engine that extracts thermal energy from pressurized steam and uses it to do mechanical work utilising a rotating output shaft. Its modern manifestation was invented by Sir Charles Parsons in 1884. It revolutionized marine propulsion and navigation to a significant extent. Fabrication of a modern steam turbine involves advanced metalwork to form high-grade steel alloys into precision parts using technologies that first became available in the 20th century; continued advances in durability and efficiency of steam turbines remains central to the energy economics of the 21st century. The largest steam turbine ever built is the 1,770 MW Arabelle steam turbine built by Arabelle Solutions (previously GE Steam Power), two units of which will be installed at Hinkley Point C Nuclear Power Station, England. The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase Synchronization
{{no footnotes, date=June 2017 Phase synchronization is the process by which two or more cyclic signals tend to oscillate with a repeating sequence of relative phase angles. Phase synchronisation is usually applied to two waveforms of the same frequency with identical phase angles with each cycle. However it can be applied if there is an integer relationship of frequency, such that the cyclic signals share a repeating sequence of phase angles over consecutive cycles. These integer relationships are called Arnold tongues which follow from bifurcation of the circle map. One example of phase synchronization of multiple oscillators can be seen in the behavior of Southeast Asian fireflies. At dusk, the flies begin to flash periodically with random phases and a gaussian distribution of native frequencies. As night falls, the flies, sensitive to one another's behavior, begin to synchronize their flashing. After some time all the fireflies within a given tree (or even larger area) will ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base units is 1/s or sā1, meaning that one hertz is one per second or the Inverse second, reciprocal of one second. It is used only in the case of periodic events. It is named after Heinrich Hertz, Heinrich Rudolf Hertz (1857ā1894), the first person to provide conclusive proof of the existence of electromagnetic waves. For high frequencies, the unit is commonly expressed in metric prefix, multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relay
A relay Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts An automotive-style miniature relay with the dust cover taken off A relay is an electrically operated switch. It has a set of input terminals for one or more control signals, and a set of operating contact terminals. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof. Relays are used to control a circuit by an independent low-power signal and to control several circuits by one signal. They were first used in long-distance telegraph circuits as signal repeaters that transmit a refreshed copy of the incoming signal onto another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations. The traditional electromechanical relay uses an electromagnet to close or open the contacts, but relays using other operati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchroscope
In AC electrical power systems, a synchroscope is a device that indicates the degree to which two systems ( generators or power networks) are synchronized with each other.Terrell Croft, Wilford Summers (ed.), ''American Electricians' Handbook Eleventh Edition'', Mc Graw Hill, 1987 pp. 7-46 - 7-48 For two electrical systems to be synchronized, both systems must operate at the same frequency, and the phase angle between the systems must be zero (and two polyphase systems must have the same phase sequence). Synchroscopes measure and display the frequency difference and phase angle between two power systems. Only when these two quantities are zero is it safe to connect the two systems together. Connecting two unsynchronized AC power systems together is likely to cause high currents to flow, which will severely damage any equipment not protected by fuses or circuit breakers. Operating principles The simplest aid to synchronizing a generator to another system uses lamps wired betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circuit Breaker
A circuit breaker is an electrical safety device designed to protect an Electrical network, electrical circuit from damage caused by current in excess of that which the equipment can safely carry (overcurrent). Its basic function is to interrupt current flow to protect equipment and to prevent fire. Unlike a fuse (electrical), fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are commonly installed in distribution boards. Apart from its safety purpose, a circuit breaker is also often used as a main switch to manually disconnect ("rack out") and connect ("rack in") electrical power to a whole electrical sub-network. Circuit breakers are made in varying current ratings, from devices that protect low-current circuits or individual household appliances, to switchgear designed to protect high voltage, high-voltage circuits feeding an entire city. Any device which pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beat Frequency
In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, ''perceived'' as a periodic variation in volume whose rate is the difference of the two frequencies. With tuning instruments that can produce sustained tones, beats can be readily recognized. Tuning two tones to a unison will present a peculiar effect: when the two tones are close in pitch but not identical, the difference in frequency generates the beating. The volume varies as in a tremolo as the sounds alternately interfere constructively and destructively. As the two tones gradually approach unison, the beating slows down and may become so slow as to be imperceptible. As the two tones get further apart, their beat frequency starts to approach the range of human pitch perception, the beating starts to sound like a note, and a combination tone is produced. Mathematics and physics of beat tones This phenomenon is best known in acoustics or music, though it can be found in any ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transformer
In electrical engineering, a transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple Electrical network, circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer's core, which induces a varying electromotive force, electromotive force (EMF) across any other coils wound around the same core. Electrical energy can be transferred between separate coils without a metallic (conductive) connection between the two circuits. Faraday's law of induction, discovered in 1831, describes the induced voltage effect in any coil due to a changing magnetic flux encircled by the coil. Transformers are used to change Alternating current, AC voltage levels, such transformers being termed step-up or step-down type to increase or decrease voltage level, respectively. Transformers can also be used to provide galvanic isolation between circuits as well as to couple stages of signa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incandescent Light Bulb
An incandescent light bulb, also known as an incandescent lamp or incandescent light globe, is an electric light that produces illumination by Joule heating a #Filament, filament until it incandescence, glows. The filament is enclosed in a glass bulb that is either vacuum, evacuated or filled with inert gas to protect the filament from oxidation. Electric current is supplied to the filament by terminals or wires embedded in the glass. A bulb socket provides mechanical support and electrical connections. Incandescent bulbs are manufactured in a wide range of sizes, light output, and voltage ratings, from 1.5 volts to about 300 volts. They require no external Regulator (automatic control), regulating equipment, have low manufacturing costs, and work equally well on either alternating current or direct current. As a result, the incandescent bulb became widely used in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diesel Engine
The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which Combustion, ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to Mechanics, mechanical Compression (physics), compression; thus, the diesel engine is called a compression-ignition engine (CI engine). This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine (gasoline engine) or a gas engine (using a gaseous fuel like natural gas or liquefied petroleum gas). Introduction Diesel engines work by compressing only air, or air combined with residual combustion gases from the exhaust (known as exhaust gas recirculation, "EGR"). Air is inducted into the chamber during the intake stroke, and compressed during the compression stroke. This increases air temperature inside the Cylinder (engine), cylinder so that atomised diesel fuel injected into the combustion chamber ignites. The torque a dies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
