Polymeric composite insulators are subjected to varying work conditions like rain and heat, which create an impact on degradation during their long service period. Electrical tracking under the Alternating Current (AC) field plays a predominant role in surface degradation, which can be different for fresh and aged insulations. The tracking studies on the fresh and aged polymeric insulation therefore become significant. Motivated by this, an indigenous low-cost electrical tracking setup was developed, and the tracking studies were carried out as per International Electro technical Commission standard (IEC) 60587 on fresh, thermal-aged and water-aged silicone rubber samples. Contact angles of samples were measured to analyse the effect of ageing on hydrophobicity. Further, to analyse the influence of ageing on insulation integrity, tracking tests were conducted and parameters like leakage current pattern and magnitudes, tracking length and loss of weight in the material due to tracking were examined. The physicochemical impacts of ageing on the surface degradation of the samples were also analysed using X-ray diffraction analysis and Fourier Transform Infrared Spectroscopy analysis. The investigations added insight into the degradation mechanism of polymeric insulators in terms of their electrical performance and physicochemical changes in the material. Comparison of these changes showed that ageing could influence surface degradation of samples.

Micro-sized aluminum trihydrate (ATH) filled silicone rubber is useful as insulation in the electric power system. The addition of nanofillers can improve further, its overall performance. However, the degradation of such silicone insulator due to ageing has not yet been thoroughly analysed. Motivated by this, an investigation was done to observe the effect of ageing on the tracking, and the material characteristics of SiO2 nanofillers added micro-sized ATH-filled Silicone rubber. For this, the samples were prepared using different weight percentage of SiO2 nanofillers and were thermally-aged and water-aged in the laboratory environment. A well-regulated tracking-test setup was assembled, and the leakage current characteristics of the fresh, thermal-aged and water-aged samples were observed, as per international electro technical commission standard (IEC) 60,587. After tracking, the surface morphology of these samples was studied using scanning electron microscopy (SEM). Further, energy dispersive X-ray analysis (EDAX) was carried out to observe the elements present at the surface and, Fourier transform infra-red (FTIR) spectroscopy was conducted to study the changes in the chemical structure. Investigations through the leakage current, SEM, EDAX and FTIR revealed that the addition of nanofillers improved the tracking characteristics of the aged hybrid composite insulation samples, thereby minimising any early failures.