Also found in: Dictionary, Thesaurus, Medical, Acronyms.

alternating current

An electric current that varies periodically in value and direction, first flowing in one direction in the circuit and then flowing in the opposite direction; each complete repetition is called a cycle, and the number of repetitions per second is called the frequency; usually expressed in Hertz (Hz).
References in periodicals archive ?
Green claims that a-c motors have certain advantages in cooling arrangements over their brush-type d-c counterparts.
There have been significant advances in both a-c motors and electronics that are making a-c drive packages more attractive for extrusion applications.
Also, brushless d-c motors are not subject to thermal problems at very low speeds, which Lee singles out as a drawback of a-c drives.
98 -is better than both brush-type d-c and most a-c inverter drives.
Lee disputes competitors' claims that a-c drives have high power factor.
In a-c drives with no input inductor - and many do not have the same wave shape.