Hybrid nanostructured coating of XLPE insulation: effect on partial discharge activity

The effect on partial discharge activity of the application of hybrid organic-inorganic nanostructured coating to XLPE insulation is investigated in this paper. Specimens having an embedded flat cavity were manufactured and coated with two different silica-based nanocoating obtained by sol-gel process. Aging tests under ac voltage were performed and partial discharge activity taking place in the cavity was monitored and compared to that occurring in uncoated specimens. Results show that coated materials are affected by less intense partial discharge activity, in terms of amplitude and repetition rate, than pure XLPE. In particular, partial discharge activity decreases more quickly with aging time with respect to uncoated materials. This fact could be associated with the good impermeability to oxygen shown by the hybrid nanocoating here used. Oxygen, in fact, is a driving factor for partial discharges and for polymer degradation caused by partial discharges.