More losses

Heavier in weight

Poor voltage regulation

Cannot isolate the secondary winding

Air natural

Oil natural air blast

Oil forced air forced

Oil natural air natural

Steel 97% and silicon 3%

Steel 95% and silicon 5%

Steel 93% and silicon 7%

Steel 90% and silicon 10%

Maintain primary voltage constant

Change voltage ratio in distribution

Maintain secondary voltage constant

Load the transformer for maximum efficiency