Accumulative insulation characteristics of 110kV GIS spacer under repeated impulse voltages

During the factory inspection and service life, the Gas Insulated Switchgear (GIS) is continuously and unavoidably subjected to repeated impulse voltages, which may cause irreversible damage to the solid insulation. The impact of these repeated impulse voltages on the insulation performance of the spacer needs to be studied. In this paper, an experimental setup for appling impulse voltages repeatedly to spacers in 110kV GIS was built. The impact of repeated lightning and switching impulse voltages on the insulation performance of the spacer had been studied with clean condition. In addition, the impact of repeated lightning impulse voltages on the insulation performance of the spacer under metallic particle contamination had been also researched. Experimental results show that the accumulative effect of spacer under repeated impulse voltages is little, and the impact on the insulation performance of spacers in GIS on-site is little, whether in clean condition or small metal particle contamination. However, once the size of metal particle exceeds a certain length, the spacers will flash over directly under the possible occurrence of lightning impulse voltage in 110kV GIS on-site.