Multistress Ageing of 28 kV Silicone Rubber Insulators under West and East Coast Conditions of the USA

Long term ageing of polymeric insulators was performed simulating coastal San Francisco and Boston. 28 kV silicone rubber insulators were used for this purpose. The same insulator (design and material) was compared at two different locations (West and East Coasts of the USA-San Francisco and Boston). Weather cycles simulating coastal San Francisco and Boston were developed. The various stresses applied include UV radiation, salt fog to simulate contamination from air-borne particles, clear mist, rain, heat, cold and electrical stress. Data acquisition of the leakage current and cumulative charge is also done by LabVIEW. High voltage divider was used to measure 20 kV using LabVIEW at 2V. They were aged for thousands of hours and their ageing and degradation were characterised using physical (discolouration, chalking, cracking, hydrophobicity), electrical (surface leakage current, cumulative charge and watts loss) and state- of-the-art material diagnostic techniques such as FTIR, SEM and XPS. Results indicate that silicone rubber insulators withstood these stresses well.