Dielectric response—A nondestructive approach to probing the micro‐interface of aluminium hydroxide filled silicone rubber composites for outdoor insulation

Abstract

Abstract Composite polymer dielectrics have strong electrical, mechanical, thermal and environmental properties but experience both high electric fields and harsh environmental conditions as outdoor insulation. The present investigation of the stress‐strain characteristics and morphology of the fracture cross‐section reveal the risk of a weakly bonded interface between the aluminium hydroxide (ATH) filler and silicone rubber used for insulators in transmission lines and substations. Dielectric response measurements are proposed as a non‐destructive probe of the interface quality. An analysis, based on the Dissado–Hill model, indicated that the introduction of ATH interfaces gave rise to a quasi‐DC process, in which charge transport is in the form of hopping along the weakly bonded interfaces. A schematic plan is proposed that would allow such an analysis to be used to obtain quantitative information correlated to the status of the weakly bonded interface for the diagnosis of micro‐interface quality in ATH‐filled silicone rubber and dielectric composites in general.