Polymer concrete outdoor insulation - Experience from laboratory and demonstrator testing

This study investigates the potential and limits of polymer concrete for outdoor insulation. Polymer concrete with a UV resistant cycloaliphatic epoxy matrix and a filler content of up to 87.5 wt% was formulated. Whereas an increase in filler content reduced strain to failure to about 0.46% (porcelain: 0.1%; 66 wt% filled epoxy: 1.26 %) the Young's modulus in compression drastically increases up to 38 GPa (compared to about 10 – 15 GPa for a standard silica filled epoxy). Burst tests performed on 72 kV model insulators qualitatively showed a significantly safer burst behavior compared to porcelain. The increasing filler content compared to the epoxy reference (65 wt.-%) had a positive effect on the resistance to tracking and erosion - samples passed 4.5 kV - and the dry-arc resistance. Dielectric breakdown strength, permittivity and loss values deteriorated, but were still in an acceptable range. Overall the material is a viable alternative to porcelain insulation, especially for parts with a moderate electrical and environmental stress.