Dry type transformers  step  up or step  down types which  are commonly 

used in buildings, machines, and appliances.Transformers adjust the voltage

coming  into the  machines to  the proper level and pump the electricity through

it to  keep  it operating properly. Transfomers are also classified induction or

auto type transformers. Auto type  is  commonly  preferred  with single tapped winding opposed to isolation type with two separate windings, auto transformer

is more lighter, smaller and provide greater stability and overload tolerance