Auto Transformer
An autotransformer is a somewhat electrical transformer where essential and auxiliary offers the same basic single winding. So fundamentally it's a one winding transformer.

Theory of Auto Transformer
In Auto Transformer, one single winding is utilized as essential twisting and also auxiliary winding. In any case, in two windings transformer, two unique windings are utilized for an essential and auxiliary reason. An outline of the autotransformer is demonstrated as follows.
The twisting AB of aggregate turns N1 is considered an essential winding. This winding is tapped from point ′C′ and part BC is considered as an auxiliary. How about we expect the quantity of turns in the middle of focuses ′B′ and ′C′ is N2.