Influence of Nanofillers on the Surface Electrical Discharge Resistance of Epoxy Insulation Used in HV Power Apparatus

Resistance to surface electrical discharge was investigated for epoxy alumina and epoxy silica nanocomposites. Epoxy alumina nanocomposites with 0.1, 1, 5, 10 and 15 wt% nanoalumina fillers as well as epoxy silica nanocomposites with 0.1, 1 and 5 wt% nanosilica fillers were prepared in the laboratory using direct dispersion method. Experiments were conducted at 10kV ac voltage for different durations using IEC (b) type electrodes. The degradation of the sample surfaces were analyzed using SEM techniques, surface roughness measurements and FTIR spectroscopy. The effect of interface on the material properties were investigated by DSC analysis. It was observed that the resistance to surface degradation improved for both epoxy alumina and epoxy silica nanocomposites as compared to the performance of unfilled epoxy. Also epoxy alumina nanocomposites showed better resistance to degradation as compared to epoxy silica nanocomposites for all the filler concentrations considered. The enhancement in degradation resistance for epoxy nanocomposites is attributed to the surface modifications of the nanocomposites when exposed to discharges and the nature of the interface in the region around the nanoparticles. The filler concentration and thereby the interparticle distance also has a significant effect on the discharge degradation resistance.