A dry-type transformer is a motionless piece of equipment that uses environmentally acceptable temperature insulation systems. They are also known as “cast resin type transformers.” The transformer is housed in a case with adequate ventilation, which results in the coils being cooled by the air inside the case.

Unlike their liquid-filled counterparts, dry-type transformers do not incorporate liquid to dissipate excess heat and meet temperature classification requirements. Instead, the coils within a dry-type transformer are constructed of a gaseous or dry insulation medium.