Research on interface charge behaviour and electrical threshold in layered epoxy/paper composites: From experiment to simulation

Abstract

Layered epoxy/paper composites that exhibit excellent insulating characteristics under elevated electrification and temperature conditions are essential components for power system insulation. Yet, inevitable charge accumulation occurs at hetero interfaces between layers due to interfacial polarisation and interface barrier effect, bringing about local electric field distortion and potential risk of partial discharge. A fundamental challenge is either to obtain accurate interface charge behaviours of in-service multi-layer insulating composites, or to construct verified simulating models for replacing experiments. Herein, a modified bipolar charge transport model to simulate interface charge behaviours in layered composites is proposed. With model parameters directly originated from equivalent experiments (e.g. conduction current measurement, thermally stimulated depolarisation current testing, and ultraviolet-visible spectroscopy) of epoxy/paper composites, the simulated temperature-dependent interface charge characteristics match well with pulsed electro-acoustic results. Furthermore, electrical thresholds can also be accurately calculated using such models (maximum deviation of 8.44% from experimental results), providing references for optimised insulation structural design.