Abstract: A hardenable epoxy resin composition which is suitable for the production of an electrical insulation with improved thermal ageing properties, wherein said hardenable epoxy resin composition comprises an epoxy resin, a hardener, an inorganic filler composition, and a coupling agent for improving the bonding between the polymer matrix and the filler, and optionally further additives. The filler composition comprises silica and aluminum trihydride (ATH). The composition can be used for the production of an electrical insulation, and electrical articles containing such an electrical insulation system.

Abstract: An epoxy resin formulation is disclosed. Such a formulation is suitable for the use as coil insulation material, wherein the formulation includes (a) a purified grade of at least one diglycidyl ether of a bisphenol compound or at least one cycloaliphatic diglycidyl ether compound or a mixture of such compounds, wherein the compounds have an epoxy equivalent weight not exceeding 10% of the minimum epoxy equivalent weight calculated for each compound; and (b) the formation optionally includes up to 50% by weight of a diglycidyl ether of a bisphenol compound or of a cycloaliphatic diglycidyl ether compound or a novolac epoxy or a mixture of such compounds, wherein the compounds have an epoxy equivalent weight exceeding 10% of the minimum epoxy equivalent weight calculated for each compound; and (c) a polymerization catalyst.

Abstract: A dry-type transformer is disclosed wherein the transformer coils are encapsulated with a cured mineral filler containing cyanate ester resin composition which optionally is a cured mineral filler containing epoxy modified cyanate ester resin composition. A method of making the insulating composition, and the non-cured composition, are also disclosed.