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Polyphase electrical systems supply alternating current electrical power in overlapping phases. The most common example are three-phase power systems used in industrial applications. An alternating current (AC) is an electrical current, where the magnitude and direction of the current varies cyclically, as opposed to direct current, where the direction of the current stays constant. ...
Transmission lines in Lund, Sweden Electric power, often known as power or electricity, involves the production and delivery of electrical energy in sufficient quantities to operate domestic appliances, office equipment, industrial machinery and provide sufficient energy for both domestic and commercial lighting, heating, cooking and industrial processes. ...
Phase, from the Greek phasis, meaning appearance, has a number of related meanings in English. ...
Three-phase power transformer which is the sole transferpoint for electricity to a suburban shopping mall in Canada. ...
Phases Polyphase systems have two or more phases. The voltage on each phase is a sine wave, with a fixed time offset, or phase shift, between the phases. Modern utility power generation and distribution is almost universally three phase, with the phases separated by 120° or one third of an AC cycle. It is commonly used in industry, as it is ideally suited to powering the 3-phase induction motor. Residences and small businesses are usually supplied with a single phase taken from one of the three utility phases. Individual customers are distributed among the three phases to balance the loads. In trigonometry, an ideal sine wave is a waveform whose graph is identical to the generalized sine function y = Asin[ω(x − α)] + C, where A is the amplitude, ω is the angular frequency (2π/P where P is the wavelength), α is the phase shift, and C is the...
Waves with the same phase Waves with different phases The phase of a wave relates the position of a feature, typically a peak or a trough of the waveform, to that same feature in another part of the waveform (or, which amounts to the same, on a second waveform). ...
The generation of AC electric power is commonly three phase, in which the waveforms of three supply conductors are offset from one another by 120°. These three conductors are commonly housed in a single conduit (e. ...
A few older installations in the U.S. used two phase four-wire systems for motors. The chief advantage of these was that the winding configuration was the same as for a single-phase capacitor-start motor. Most of these have been upgraded to three-phase systems. A two-phase supply with 90 degrees between phases can be derived from a three-phase system using transformers in a Scott connection. Two-phase electrical power was used in some early 20th century factories and the distribution systems that served them. ...
In North America most houses, small apartments and small businesses are supplied from a single-phase utility transformer with a three-wire 120/240 volt (nominal) secondary. One of the wires -- the neutral -- is grounded; the other two are hot. Each hot wire is at 120V with respect to the neutral, but the phase offset between the two hot wires is 180° so that the AC voltage between the hot wires is 240V. This supply is used by high-power appliances such as electric Ovens/ranges, clothes dryers and central air conditioning systems. Such systems are sometimes referred to as split phase and are sometimes incorrectly referred to as two phase. An oven is an enclosed compartment for heating, baking or drying. ...
Split phase is a mains electrical supply system mainly used in North America ( which may be incorrectly referred to as two phase). ...
Many larger apartment buildings are fed with 3-phase transformers, with two of the three phases fed to each unit. The phase offset between the two hot wires is therefore only 120 degrees, so that while the voltage from each "hot" wire to neutral is 120V, the voltage between hot wires is only 208V. Most appliances rated for 240V will run satisfactorily on 208V, but special autotransformers can boost 208V to 240V if necessary.
Motors Polyphase power is particularly useful in AC motors, particularly the induction motor, where it generates a rotating magnetic field. When a three-phase supply completes one full cycle, the magnetic field has rotated through 360°. An alternating current (AC) is an electrical current, where the magnitude and direction of the current varies cyclically, as opposed to direct current, where the direction of the current stays constant. ...
Electric motors of various sizes. ...
In physics, a magnetic field is an entity produced by moving electric charges (electric currents) that exerts a force on other moving charges. ...
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