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Mathematics and basic principles of three-phase electric power. One voltage cycle of a three-phase system, labeled 0 to 360° (2π radians) along the time axis. The plotted line represents the variation of instantaneous voltage (or current) with respect to time. This cycle repeats with a frequency that depends on the power system.
Three-phase transformer with four-wire output for 208Y/120 volt service: one wire for neutral, others for A, B and C phases. Three-phase electric power (abbreviated 3ϕ[1]) is a common type of alternating current (AC) used in electricity generation, transmission, and distribution. [2] It is a type of polyphase system employing three wires (or ...
One voltage cycle of a three-phase system. A polyphase system (the term coined by Silvanus Thompson) is a means of distributing alternating-current (AC) electrical power that utilizes more than one AC phase, which 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.
A "transformer bank", widely used in North America: three single-phase transformers connected to make a 3-phase transformer. The low-voltage secondary windings are attached to three or four terminals on the transformer's side. In North American residences and small businesses, the secondary is often the split-phase 120/240-volt system. The 240 ...
In Europe, three-phase 230/400 V is most commonly used. However, 130/225 V, three-wire, two-phase electric power discontinued systems called B1 are used to run old installations in small groups of houses when only two of the three-phase high-voltage conductors are used. The phase shift in Europe is 120°, as is the case with three-phase current.
A Scott-T transformer or Scott connection is a type of circuit used to produce two-phase electric power (2 φ, 90 degree phase rotation) [1] from a three-phase (3 φ, 120 degree phase rotation) source, or vice versa. The Scott connection evenly distributes a balanced load between the phases of the source. The Scott three-phase transformer was ...
Fractions such as 1 ⁄ 3 are displayed as decimal approximations, for example rounded to 0.33333333. Also, some fractions (such as 1 ⁄ 7, which is 0.14285714285714; to 14 significant figures) can be difficult to recognize in decimal form; as a result, many scientific calculators are able to work in vulgar fractions or mixed numbers.
The second one was a programmable mechanical calculator, his analytical engine, which Babbage started to design in 1834; "in less than two years he had sketched out many of the salient features of the modern computer. A crucial step was the adoption of a punched card system derived from the Jacquard loom" [12] making it infinitely programmable ...