Method for impregnating and embedding electrical windings

US4576768A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Helmut Markert · Nuremberg, DE
• Wolfgang Rogler · Erlangen, DE
• Wolfgang Bendel · Leonberg, DE
• Friedrich Alber · Köngen, DE

Key dates

• Filing date: Jun 27, 1984
• Grant date: Mar 18, 1986
• Expiry date: Jun 27, 2004

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01F41/127
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

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.