Performance of Silicone Rubber Insulators Under Thermal and Electrical Stress

In recent times, high temperature vulcanized (HTV) silicone rubber insulators (SIR) are being widely used for overhead high voltage transmission and distribution systems. However, over a period, the insulator surface will be exposed to high temperature in several places, particularly in desert areas; further accumulation of pollutants can alter the temperature distribution along the insulator. In the present work, long-term electrothermal experimentation is carried out on various types of full-scale insulator units. The effect of temperature on pollution performance of SIR insulators is studied, and a novel and simple methodology to achieve uniform contamination layer on inherently hydrophobic HTV SIR insulator samples is presented. A specially fabricated oven having a provision for high voltage connection and facility for measurement of leakage currents is provided. Furthermore, study of migration of low molecular weight, recovery trends of hydrophobicity, and changes in material properties using scanning electron microscopy Fourier transform infrared spectroscopy is carried out.