Overview of Dielectric Properties of Epoxy-glassmica Layered Composites with Incorporated Polymeric Films

Abstract

This paper proposes an addition of polymeric film layers into a conventional high-voltage insulating composite. The effects of the addition of such fourth component to a standard three-component composite are assessed. Tested specimens were prepared as thin sheets of conventional prepregs with fibre reinforcement to which separate polymeric films were added. The first type of prepared composites consisted only of three-component prepregs and was the reference material. The other three prepared composites consisted of prepregs with incorporated polymeric films of polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). Volume resistivity, relative permittivity, loss factor, and partial discharge activity were measured on the press-cured specimens of layered composites. The measurement results were compared between the reference and composites incorporating different polymeric films. The results indicate that the primary differences between reference and composites with polymeric films are in the volume resistivity and dissipation factor. Analysis of partial discharge activity reveals varying behaviour between tested composites based on phase-resolved partial discharge patterns.