Multistress Aging Studies on HTV Silicone Rubber Insulators

Polymeric insulators arc used for overhead transmission line insulation due to various advantages, but long term performance and estimation of service life is still a challenge. During service life, these insulators are stressed under different mechanical, electrical, environmental stresses etc. and over a period, they lose their insulation properties. In the present work, an attempt is made to study the effect of multiple stresses like thermal, ultra violet (UV) radiation, humidity along with electrical stress on the long term performance. These stresses are applied in a specific cyclic manner to closely meet the real climatic service conditions. During experimentation leakage current is monitored regularly. Physicochemical analysis is performed using Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis (EDAX) to find elemental composition changes during experiment and Thermo-Gravimetric Analysis (TGA) is used to analyze the thermal stability. Fourier transform infrared (FTIR) spectroscopy is performed to detect chemical changes and surface hydroxylation in aged insulating samples. Further, the effect of multiple stresses on tensile strength is observed and reported