Machine Design

http://en.wikipedia.org/wiki/Transformer

For designing any transformer fist you have to calculate your total load,i.e.-what should be the power of transformer at what voltage and what type (step up,step down or auto) you have previously fixed.Suppose if you want to design 1kva ,250v auto transformer.then total maxm cuuent will be 1000/250=4 i.e. 4A,widding wire should be such that it can sustain 4A. for more reading you can help in www.gigapedia.com

please conform you want to prectically design or theoritically

Dear Friend,

Please read - The Design and Performance of AC machines by Mr.M.G.Say.

This book gives the Design of Transformers , Motors and Generators fully.

Go and join any Engg.college and avoid such silly questions. Did not

Electrical machine Design form a part of your study ?

Manroop. Chennai.