A dry high voltage (HV) instrument transformer in the form of a HV current transformer includes a core casing having a secondary winding, a top housing, a primary winding, and a dry bushing, wherein the core casing comprises an insulation containing an electrically insulating material made of PES nonwoven impregnated and cured with low viscosity epoxy. The dry HV instrument transformer in the form of a HV voltage transformer includes a bottom tank housing, a cast of a primary winding module with an embedded screen surrounding the primary winding, a field grading disc, and a core, wherein the cast of the primary winding module is made of an insulating composite containing an electrically insulating material made of PES nonwoven impregnated and cured with low viscosity epoxy.