Influence of electrode surface pretreatment and multi-layer dielectric coatings on electric insulation properties in GIS

Smaller Gas Insulated Switchgear (GIS) size and environment-friendly substitution of SF6 gas are strongly required for reducing substation area and lower Global Warming Potential (GWP). But the smaller size and usage of alternative gases may cause fatal electric insulation problem. Recently, the insulation property has been improved by dielectric coating on the surface of inner conductors at GIS. Many coating materials with thickness of several micrometers to centimeter have higher electric insulation strength than SF6 gas, so they can endure the concentrated electric field. We made multi-layer coatings that have different dielectric constants and single layer coatings with dielectric materials of low dielectric constants. In case of multi-layer coating aluminium oxide (Al2O3) at inner…