Electrical Laminations

Core laminations are the main part of an electrical transformer, and this attribute to 70% of a transformer cost. These core laminations are required to be cut from special steel called as Cold Rolled Grain Oriented Electrical Steel or popularly known as CRGO. The CRGO is a special quality of steel which have a special grain surface and comes in a thickness of 0.23 mm, 0.27 mm, 0.30 mm, 0.35 mm. (generally called M3, M4, M5 & M6). Lower the thickness of material better is the quality of material.
The Quality of CRGO is measured in terms of lower losses of electrical current, which flow in the core. The proper design of core and good quality of core material do a best job in combination. Mainly the core losses are measured in Watts per Kg.
Every type of steel has "grains" which consist of "domains". These "domains" are nothing but electrical charges oriented in any random direction. Therefore if a transformer were to be made of Mild Steel used as core material, the core loss would be approx. 16 to 17 wkg at 1.5T50Hz and the size of the transformer would be approx. 18 to 20 times the size of a transformer manufactured with GO steels.