Suggests certain points to choose a medium power tranformer. Tranformer, itself consists of a magnetic core, primary and secondary winding, a tank filled with cooling fluid and a few attachments. It briefly discusses the choice and standardization of the level of no load losses and losses under load. Copper, used in the winding of the transformer makes most part of its cost. The copper winding is compared with aluminum winding. Comparison has been made between the electrical characteristics, and mechanical characteristics of copper and alluminium. The choice of the dielectric and of the cooling system have been compared. An alternate solution consisting of a "Sililcone" based oil has also been noted. Finally the dry types transformer and the problems associated with this type and its advantages have been highlighted.