Abstract: The invention relates to a heat-hardened molded material produced from a resin mixture of a polyfunctional epoxide, a polyfunctional isocyanate and a reaction accelerator, which optionally contains additives and/or fillers. The objective is to make a resin mixture which permits the manufacture of a highly heat-resistant molded material, and which has at the same time a high-temperature cycle resistance and good mechanical properties. For this purpose, the polyfunctional epoxide of the resin includes a polyoxyalkylene glycol polyglycidyl ether.

Abstract: The invention relates to a method for impregnating and embedding electrical windings, especially coils of transformers, by means of an impregnating or casting resin based upon polyepoxide-polyisocyanate mixtures in the presence of a reaction accelerator latent at the processing conditions, which employs conditions that prevent the formation of gas and shrinkage voids in the cast in winding. To this end, the resin including, if applicable, additives, is dried at reduced pressure and while stirring at temperatures of up to 110.degree. C. and the winding is cast-in with the dried resin at reduced pressure and at temperature of up to 110.degree. C.; then the reduced pressure is removed and the winding is exposed to overpressure. Subsequently, generating by an elevated temperature in the electrical winding by Joule heat in the conductor, the cross-linking reaction of the resin is started and is controlled as a function of the reaction heat, until the winding is removed from the mold and post-hardened.

Abstract: Method of manufacturing a transformer winding embedded in casting resin by winding coils respectively by themselves and independently of one another for disposition thereof in tandem in axial direction of the winding includes placing the wound coils in a substantially annular casting mold having an inner and an outer jacket, with respective impregnated corrugated mats of insulating material as spacers disposed between the inner jacket and the coils as well as between the coils and the outer jacket, the inner and the outer jackets being fixed between mold end walls at respective ends of the casting mold; and disposing the casting mold containing the wound coils in an evacuated chamber and pouring casting resin into the casting mold through an axially parallel slot formed in the outer jacket thereof.

Abstract: Multiphase transformer for power distribution in a supply network includes a single block of cast resin having high voltage and low voltage conductor windings embedded therein, and an iron core with a plurality of legs and an upper and lower yoke formed of closely-stacked transformer laminations centrally embedded in the block, the block having axially-extending ribs integral therewith defining troughs between the ribs and defining spaces between the ribs and the core, legs and yokes, watertight caps disposed between the ribs closing off the troughs and holding the core, legs and yokes, and mechanically compacted dry quartz sand filled in the space.