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Reference: ISH2015_165

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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 layer and Poly Tetra Fluoro Ethylene (PTFE) at outer layer were used. To compare breakdown characteristic between multi-layer and single layer coating, fluoropolymer such as Per Fluoro Alkoxy alkane (PFA) and Ethylene Tetra Fluoro Ethylene (ETFE) with low dielectric constant applies to single layer. It includes the effect of thermal stress on dielectric coating. Additionally, the effect of surface roughness of aluminium electrode on insulation strength was estimated after surface treatment. The experimental setup consists of coated sphere-plane electrode configuration in test chamber filled with SF6 gas at 0.4Mpa.

File Size: 465,1 KB

Year: 2015

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