Autotransformer

An Autotransformer (sometimes called autostep down transformer)Paul Horowitz and Winfield Hill, The Art of Electronics Second Edition, Cambridge University Press, Cambridge MA, 1989, , page 58 is a transformer which has 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. The winding acts as both primary winding and secondary winding in a normal transformer. Since part of the winding does "double duty", autotransformers have the advantages of often being smaller, lighter,John Winders, Power Transformers: Principles and Applications (New York; Basel: Marcel Dekker, Inc., 2002), p. 132 and cheaper than typical dual-winding transformers. The disadvantage of an autotransformer include not providing electrical isolation between the primary winding and the secondary winding.Smarajit Ghosh, Electrical Machines, Second Edition (Delhi: Pearson, 2012), p. 101 There is also a higher possibility of short circuits due to low impedance.

Usage
Autotransformers are used in power transmission, power distribution, audio, rail transport, etc. Autotransformers are often used to step up (increase) or step down (decrease) voltages in the 110–120 V range and in the 220–240 V range.

 References 

 Other websites 

 The Basics of Autotransformers
 Difference between Isolation Transformers and Autotransformers

Category:Electricity
Category:Electrical wiring