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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 ...
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 ...
It can also change the voltage or frequency of the current. Power converters include simple devices such as transformers, and more complex ones like resonant converters. The term can also refer to a class of electrical machinery that is used to convert one frequency of alternating current into another.
A current in a wire or circuit element can flow in either of two directions. When defining a variable to represent the current, the direction representing positive current must be specified, usually by an arrow on the circuit schematic diagram. [12] [13]: 13 This is called the reference direction of the current .
Angle notation can easily describe leading and lagging current: . [1] In this equation, the value of theta is the important factor for leading and lagging current. As mentioned in the introduction above, leading or lagging current represents a time shift between the current and voltage sine curves, which is represented by the angle by which the curve is ahead or behind of where it would be ...
In Engineering Electromagnetics, Hayt points out that in a power station a busbar for alternating current at 60 Hz with a radius larger than one-third of an inch (8 mm) is a waste of copper, [20] and in practice bus bars for heavy AC current are rarely more than half an inch (12 mm) thick except for mechanical reasons.
A current transformer is designed to maintain an accurate ratio between the currents in its primary and secondary circuits over a defined range. The alternating current in the primary produces an alternating magnetic field in the core, which then induces an alternating current in the secondary. The primary circuit is largely unaffected by the ...
A converter from alternating to direct current, where switching devices actively are operated in step with the positive and negative excursions of the supply. synchroscope An instrument used to bring an alternating current generator into synchronization with a grid, that uses a moving pointer or set of lamps. system identification