What is Autotransformer
Electrical transformer with only one winding, with two end terminals, and one or more terminals at intermediate tap points.Used to interconnect systems operating at different voltage classes, providing conversions between the two common domestic mains voltage bands in the world (100-130 and 200-250).special autotransformers with automatic tap-changing equipment are inserted as voltage regulators, special form of autotransformer called a zig zag is used to provide earthing on three-phase systems that otherwise have no connection to earth.Tapped autotransformers are used to adapt speakers to constant-voltage audio distribution systems, and for impedance matching
An autotransformer (sometimes called autostep down transformer) is an electrical transformer with only one winding. The "auto" (Greek for "self") prefix refers to the single coil acting on itself and not to any kind of automatic mechanism. In an autotransformer portions of the same winding act as both the primary and secondary. The winding has at least three taps where electrical connections are made. Autotransformers have the advantages of often being smaller, lighter, and cheaper than typical dual-winding transformers, but autotransformers have the disadvantage of not providing electrical isolation. Read more at :[http://en.wikipedia.org/wiki/Autotransformer]
