Experimental investigation on the accelerated aging of silicone rubber insulators based on thermal stress

During recent decades, polymer insulators have become very popular due to their many advantages over other insulators. Since observing noticeable changes and signs of aging on insulators in the power grid requires a long time, therefore laboratory studies focusing on the accelerated aging of polymer insulators help to identify materials and study the trend of insulation changes during the aging process. In this paper, the accelerated aging of polymer insulators using thermal stress at 180 °C and 3000 h is investigated. The experience is done after investigating the effect of UV aging on insulators. During and after the accelerated thermal aging test, the electrical quality of the polymer insulator are analyzed using leakage current measurement tools, partial discharge and hydrophobicity. Analysis of surface changes are performed by Scanning Electron Microscopy, Energy Dispersive X-ray Analysis, Thermo Gravimetrical Analysis and Fourier Transform Infrared Spectroscopy in qualitative and quantitative modes. The results of different methods of the analysis show that in the thermal aging test, due to the high thermal endurance of polymer insulators, significant changes in parameters would be visible after longer aging times, so thermal aging is not practical on aging polymer insulators and is not recommended as an accelerated aging test independent of other aging tests, especially UV.