Cast resin dry type transformers are magnetic core transformers in which the windings and core are kept in a sealed tank that uses air as a cooling medium instead of oil or other liquids as in a typical liquid-filled transformer. In a cast resin dry type transformer, high-voltage (HV) and low-voltage (LV) windings are completely impregnated and cast under vacuum in epoxy resin. This encapsulation helps prevent moisture to penetrate the winding material. The insulating material offers excellent fire hazard protection; thereby, suitable for indoor installations. This makes them the preferred choice for underground or city-building substations that require site-specific fire prevention and fire contingency-management strategies.