Einfluss von Mikroholraeumen Auf die Elektrische Festigkeit Glasfaserverstaerkter Epoxidharz-Formstoffe (Influence of Microvoids on the Electrical Strength of Glass Fiber Reinforced Epoxy Resins)

摘要

The distribution of microvoids in unidirectionally glass fiber reinforced epoxy resins, and their effect on electrical strength were investigated. Experiments show that glass fibers may contain capillary voids which allow water or electrolytic liquids to penetrate the insulating system very quickly. These electrolytic liquids lead to a field distortion resulting in overstress in the insulation and partial discharges. A microscopic analysis of glass fiber reinforced epoxy rods reveals numerous small, isolated voids, concentrated in the edges between adjacent fibers. It is shown that no partial discharges occur in these voids, even under high stress, due to their small dimensions. The weak point is the interface between glass fibers and the resin matrix.