A dry-type transformer is one in which the insulating medium surrounding the winding assembly is a
gas or dry compound. Basically, any transformer can be constructed as ‘‘dry’’ as long as the ratings, most
especially the voltage and kVA, can be economically accommodated without the use of insulating oil or
other liquid media. This section covers single-and three-phase, ventilated, nonventilated, and sealed
dry-type transformers with voltage in excess of 600 V in the highest-voltage winding.