Charge Accumulation/Decumulation on DC-GIS Spacer under 10,000-hour DC Field Application

Surface charges on an insulating epoxy spacer in DC-GIS under high DC electric field lead to decrease breakdown voltage on the spacer, but charge accumulation phenomena of insulators are not clear in detail. In this paper, surface charge distributions on the epoxy model spacer were measured under DC-GIS simulated environment during the DC voltage application for 10,000 hours and the short circuit for 2400 hours. The saturation tendency of charge accumulation in which only the homo-charges develop concentrically near the electrodes was obtained. The time constant of charge accumulation below 20 degrees C agreed with the theoretical value calculated from the equivalent circuit. Surface charge characteristics with irregular charge, the ones during charge decumulation, and the relationship between charging saturation tendency and temperature were also obtained.