Transformers of different capacity, voltage level, impedance voltage, structure type, design principles, current density and the core wire flux density of the same circumstances, they approximate relationship exists between the following:

 ① transformer capacity is proportional to the linear dimensions of the 4 th power.

 ② material weight of the transformer is proportional to the effective capacity of the power of three-quarters.

 ③ transformer unit capacity consumption of material is proportional to the effective power of a quarter of capacity.

 ④ When the transformer core wire current density and magnetic flux density remains constant, the effective material loss and weight proportional to the total loss is proportional to the power of three-quarters capacity.

 ⑤ transformer unit capacity loss is proportional to the power of a quarter of capacity.

 ⑥ transformer manufacturing cost is proportional to the power of three-quarters capacity.

 Thus, in the same load conditions, the selection of a single large-capacity transformer than a few sets of small-capacity transformer to the economy.