kids encyclopedia robot

Autotransformer facts for kids

Kids Encyclopedia Facts
Tapped autotransformer
Schematic of an autotransformer
Variable Transformer 01
A variable autotransformer

An Autotransformer (sometimes called autostep down transformer) 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, 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. There is also a higher possibility of short circuits due to low impedance.


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.

Images for kids

See also

Kids robot.svg In Spanish: Autotransformador para niños

Black History Month on Kiddle
Famous African-American Pilots:
Bessie Coleman
Spann Watson
Jill E. Brown
Sherman W. White
kids search engine
Autotransformer Facts for Kids. Kiddle Encyclopedia.