Surface charge accumulation behavior on Al2O3-filled epoxy composites with rough surface under DC voltages

Surface charge accumulation on gas-solid interface becomes a potential threat to surface insulation performance. This study focuses on surface charge accumulation behavior on epoxy-based composites of different surface roughness under DC voltages. Four kinds of spacers with surface roughness ranging from 0.58 mu m to 9.24 mu m are prepared by sandblasting technology. Surface charge distribution is measured by a Kelvin vibrating electrostatic probe. It is found that surface charges are distributed in two regions, including charge ring near high voltage electrode (region A) and charge speckles away from high voltage electrode (region B). Surface rough treat can dramatically suppress charge accumulation in region B while no distinct difference is observed in region A. Increasing surface roughness could have more decent effect of surface charge suppression. It is revealed that the combination of improved surface conductivity and altered surface trap distribution are responsible for variation of surface charge accumulation behavior.