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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 cycle). "Alternating current" most commonly refers to power distribution, but a wide range of other applications are technically ...
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 four including an optional neutral return wire) and is the most common method used by electrical grids worldwide to transfer ...
Many other combinations of voltage and utility frequency were formerly used, with frequencies between 25 Hz and 133 Hz and voltages from 100 V to 250 V. Direct current (DC) has been displaced by alternating current (AC) in public power systems, but DC was used especially in some city areas to the end of the 20th century.
In a simple alternating current (AC) circuit consisting of a source and a linear time-invariant load, both the current and voltage are sinusoidal at the same frequency. [3] If the load is purely resistive, the two quantities reverse their polarity at the same time. Hence, the instantaneous power, given by the product of voltage and current, is ...
Alternating current is any current that reverses direction repeatedly; almost always this takes the form of a sine wave. [46]: 206–07 Alternating current thus pulses back and forth within a conductor without the charge moving any net distance over time. The time-averaged value of an alternating current is zero, but it delivers energy in first ...
In other media, any stream of charged objects (ions, for example) may constitute an electric current. To provide a definition of current independent of the type of charge carriers, conventional current is defined as moving in the same direction as the positive charge flow. So, in metals where the charge carriers (electrons) are negative ...
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The total current carried in all three wires (including the neutral) will always be twice the supply current of the most heavily loaded half. For short wiring runs limited by conductor current carrying capacity , this allows three half-sized conductors to be substituted for two full-sized ones, using 75% of the copper of an equivalent single ...