Characterization of nanofilled epoxy varnish subjected to surface partial discharges

An epoxy matrix varnish, used for topping treatment of electrical machines stators, was studied. The experimental nanocomposites were prepared using the same organically modified clay varying the mixing process. The nanostructure of each material was assessed by means of WAXRD. The homogeneity at the micron level was checked via SEM observations of brittle fractured sections. DSC analyses were conducted on both pure and nanofilled samples. Surface partial discharges resistance of both the nanocomposite varnishes and the traditional microcomposite, with the same epoxy matrix, was compared. Damages due to partial discharges were observed through optical microscopy and SEM, while an estimate of the surface erosion was obtained through roughness measurements.