Isovolta- Osterreichische Isolierstoffwerke Aktiengesellschaft

Helmut Gsellmann

Michael Raber

Bernard Hafner

A process for producing mica-containing insulating tape for windings of rotating high voltage electrical machinery which after winding under a vacuum and pressure can be impregnated with a solvent-free synthetic resin and then cured under the action of heat, a fiber-containing mica film which in addition to fine mica also has organic and/or inorganic fibers being sprinkled with an epoxy resin mixture in the form of a powder enamel and the side of the fiber-containing mica film which has been sprinkled with the powder enamel being cemented under pressure and at an elevated temperature to a carrier material.

Method for producing insulating tapes containing mica, and the utilization thereof

A process for producing impregnable fine mica tapes with a built-in accelerator which after winding onto the conductors of the windings of electrical machines are impregnated with a solvent-free impregnation resin and are then cured under the action of heat. The fine mica film is sprinkled with a powder epoxy resin system which contains a curing agent and the side of the fine mica film which has been sprinkled with the powder epoxy is cemented to a carrier material, the powder epoxy resin system curing under the influence of temperature.

Method for producing impregnable fine mica tapes with an incorporated accelerator

A thermally expanding laminate contains highly elastic reinforcing fibers, such as glass fibers, in the elastically compressed state, and a thermally softening, thermosetting plastic as a binder. In order to manufacture this laminate, first glass fiber mats are impregnated with a thermosetting plastic and thereupon one or more superposed mats are compressed in a press and raised to temperatures such that the plastic shall soften and the assembly then is cooled while still being compressed and while the plastic is solidifying to form the finished laminate. The expandable laminate preferably is used for electrically insulating spacers. Illustratively a laminate blank 4 is mounted between neighboring coil parts 5 of a stator of an electrical high-voltage machine. In the ensuing vacuum-pressure molding, which is conventional per se, of the stator to complete the soil insulation, the laminate blanks 4 are heated by the hot impregnation-soaking medium, the plastic of the laminate blanks being softened and these blanks then expand on account of the decompression of their compressed fiber material and entirely fill the gaps between the coil parts 5. The soaking medium totally filling the laminate pores then is jointly cured with the plastic of the laminate with the stator insulation.

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Graz, Austria

Helmut Gsellmann