Distribution transformers are used to step down the electric energy supplied from the electric grid from medium voltage to low voltage level MV / LV. They are produced with 3 different technologies that include the conservator, hermetic and dry type. The used voltage level ranges between 2kV up to 40.5Kv. Although the transformer powers are widely used between 25kVA and 2.500kVA, it is also possible to produce higher and lower powers. Transformers made of aluminum or copper conductor in line with the desired losses, expansion tank, and transformer type. Generally, ONAN cooling models are used, while models with fan are preferred for dry type transformers.