Study on AC Breakdown Characteristics of Epoxy Impregnated Fabric Based Insulation Materials

Abstract

Dry-type insulation is widely used in high voltage equipment due to its advantages of high insulation strength, superior environmental performance, good fire performance and small maintenance workload. Fabric based insulation materials have excellent insulation performance and flexibility, and are widely used in the dry-type insulation. Dry-type insulation is made of epoxy resin casting, so the epoxy wettability of fabric based insulation material and its breakdown characteristics after impregnation are the basis of design of dry-type insulation. In this paper, the epoxy wettability of three kinds of typical fabric based insulation materials, namely rayon fabric (RF), aramid paper (AP) and Dacron-Mylar-Dacron (DMD), and their breakdown characteristics under AC voltage after impregnation were tested. The results showed that the RF had the best wettability, AP had the middle wettability and DMD had the worst wettability. The statistical analysis of breakdown voltage showed that the breakdown strength of epoxy impregnated DMD was the highest, that of AP was the middle, and that of RF was the lowest, but all of them were lower than that of pure epoxy resin. The influence of the material thickness on the breakdown characteristics and the breakdown mechanism of epoxy impregnated fabric based insulation material were also analyzed.