Autotransformer

WHAT IS AUTO TRANSFORMER?

It is an Transformer with one winding only, part of this being common to both primary and secondary.

In This Transformer Primary and Secondary coil are not electrically isolated from each other as in case of two winding Transformer. But its theory and operation are similar to those transformers.

Benefit of Auto Transformer: 

As this Transformer has only one winding for that less copper required and its cheaper than others two winding transformer.

Light in weight and smaller in size.

Voltage regulation is also superior.