Long term ageing performance of Silicone rubber insulators under different conditions

Materials used in the manufacture of polymeric insulators were ethylene propylene diene monomer (EPDM) and silicone rubber (SR). Non ceramic insulators have shown good performance even in hostile environments. Silicone rubbers helped considerably to eliminate the contamination problem. Silicone rubbers have low surface energy which offers a hydrophobic surface, which does not wet the surface, offering weather ability even under contaminated conditions. This paper presents some laboratory tests being performed on SR insulators. 1000 hours salt fog test, 5000 hours of multistress ageing (different environmental conditions were simulated in a chamber and daily ageing cycle of CIGRE 5000 hours was adopted), insulators were also subjected to bio contamination and were tested under salt fog conditions for 10000 hours. Diagnostic tests were performed, tests include hydrophobicity test, energy dispersion X-ray (EDX) and X-ray diffraction (XRD) analysis, leakage current were measured at regular intervals. Results indicate that SR insulators have better ageing performance due to its hydrophobic recovery mechanism, they perform better under different conditions and it is evident that development of bio-contamination on insulator surface does not lead to any degradation of performance.