Multistress Aging Studies on Polymeric Insulators

Polymeric insulators are emerging as popular outdoor insulation for high voltage applications. However, environmental stresses along with prolonged electric discharges cause degradation to the promising properties of polymeric insulators. In present work, an attempt has been made to fabricate the experimental facility, study the multiple stresses (humidity, temperature, UV and electric stress) on HTV and LSR silicone based rubber insulators (SIR) to evaluate long-term performance under different climatic conditions. Leakage current waveforms were regularly monitored over the experimental duration of 1000 hours. Fourier transform infrared (FTIR) spectroscopy is utilized to assess the surface hydroxylation phenomenon observed on aged SIR. Salt layer is detected on all aged samples and it is found to govern the spray pattern on aged samples during wettability Class (WC) measurement. Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX) and Thermo-Gravimetric Analysis (TGA) are employed to analyze the elemental composition and thermal stability of SIR after aging. X-ray Diffraction (XRD) analysis is performed on fresh and aged samples to detect the structural changes and loss of ATH fillers before and after the experimentation. Also, the consequence of multistress aging of the tensile strength on SIR is evaluated.