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The abbreviations AC and DC are often used to mean simply alternating and direct, respectively, as when they modify current or voltage. [ 1 ] [ 2 ] 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 ...
The war of the currents was a series of events surrounding the introduction of competing electric power transmission systems in the late 1880s and early 1890s. It grew out of two lighting systems developed in the late 1870s and early 1880s; arc lamp street lighting running on high-voltage alternating current (AC), and large-scale low-voltage direct current (DC) indoor incandescent lighting ...
Direct current may be converted into alternating current via an inverter. Direct current has many uses, from the charging of batteries to large power supplies for electronic systems, motors, and more. Very large quantities of electrical energy provided via direct-current are used in smelting of aluminum and other electrochemical processes.
A block diagram of a bipolar HVDC transmission system, between two stations designated A and B. AC – represents an alternating current network CON – represents a converter valve, either rectifier or inverter, TR represents a power transformer, DCTL is the direct-current transmission line conductor, DCL is a direct-current filter inductor ...
Pulsed DC (PDC) or pulsating direct current is a periodic current which changes in value but never changes direction. Some authors use the term pulsed DC to describe a signal consisting of one or more rectangular ("flat-topped"), rather than sinusoidal, pulses.
Alternating current can also be converted to direct current through use of a rectifier. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. An old name for direct current was galvanic current. [17]
Over 98% of the current will flow within a layer 4 times the skin depth from the surface. This behavior is distinct from that of direct current which usually will be distributed evenly over the cross-section of the wire. An alternating current may also be induced in a conductor due to an alternating magnetic field according to the law of induction.
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 ...