Alternator
![Early 20th-century alternator made by Ganz Works in 1909 in Budapest, Hungary, in the power generating hall of the biggest hydroelectric station of the Russian Empire (photograph by Prokudin-Gorsky, 1911)[1]](/uploads/202501/02/Gorskii_04414u1648.jpg)
![In what is considered the first industrial use of alternating current in 1891, workmen pose with a Westinghouse alternator at the Ames Hydroelectric Generating Plant. This alternator was used as a generator producing 3000 volt, 133 hertz, single-phase AC, and an identical one 3 miles away was used as an AC motor.[5]](/uploads/202501/02/Ames_Colorado_generator_alternating_current_power_plant_1891_Gold_King_Mine1648.png)
An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature. Occasionally, a linear alternator or a rotating armature with a stationary magnetic field is used. In principle, any AC electrical generator can be called an alternator, but usually the term refers to small rotating machines driven by automotive and other internal combustion engines. An alternator that uses a permanent magnet for its magnetic field is called a magneto. Alternators in power stations driven by steam turbines are called turbo-alternators. Large 50 or 60 Hz three phase alternators in power plants generate most of the world's electric power, which is distributed by electric power grids.