Performance and ageing of polymeric insulators

Long-term field experiences of ageing and performance of polymeric silicone rubber (SIR) and ethylene-propylene-diene monomer (EPDM) insulators under natural contamination conditions in an outdoor installation are presented. The primary aim of the work is to study the interrelation between surface conditions and the electrical performance of polymeric insulators. In this paper, the leakage current statistics, the hydrophobicity and the surface conditions of six SIR and three EPDM commercially available insulators are studied in detail. The surface conditions were studied using electron spectroscopy for chemical analysis (ESCA), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM). The results show a strong interrelation between the conditions of the insulator surface, especially the hydrophobicity and the performance with respect to leakage currents and voltage withstand