STUDIO DELLA COMPOSIZIONE CHIMICA DEL DEPOSITO DI PARTICOLATO ATMOSFERICO E DELLA SUA INFLUENZA SULLA CONDUCIBILITÀ ELETTRICA DEGLI ISOLATORI DELLA RETE DI TRASMISSIONE

Saline pollution represents a risk factor for the power networks. In this study a comprehensive chemical characterization of electric insulator deposits is presented. The two main locations were Milan, which, according to IEC 60815, resulted in a lightly polluted site, and Latina, a coastal mediumly-polluted site. Weathering, face of the insulator, vertical profile of and the presence of a hydrophobic coating were the studied factors. Weathering effect was predominant and synergic with the complex system of phenomena in act: vertical profile was in fact responsive to rain wash-off, while correlation with face factor was masked. The coating was responsible of high-risk situations during the hot period. Significative differences were observed between air particulate matter composition and deposits composition because of deposition itself and evolution phenomena: the deposit, despite atmospheric PM composition, is enriched in bicarbonates, calcium, sodium and chlorides while lacking largely ammonium sulphate and nitrate, newborn seasonality was also observed. Regarding carbonaceous, OC/EC ratio proved to be a peculiar characteristic in deposits being higher than in air up to a factor 10. The main campaigns were supported by intensive ones. Finally, a national campaign gave an idea of pollutant distribution over insulator throughout Italy: OC is more abundant in the southern, while EC in the northern. This work poses the basis for alert systems based on modelling tools. It is unparalleled in Italy and represents a step towards the resilience of the Italian electrical system.