Aging studies on polymeric insulators under DC stress with controlled climatic conditions

In the present investigation, long term service performance of silicone rubber based polymeric insulators under DC stress with controlled climatic conditions is attempted. Simultaneous application of UV, thermal, humidity with DC electrical stress is applied to polymeric insulators enclosed in a specially fabricated climatic chamber. The stresses are applied for 1000 h for an adopted cycle to simulate close service life conditions. The leakage current is regularly monitored and recorded. After the experimentation, samples of the aged specimen are subjected for post analysis and psycho-chemical analysis like Scanning Electron Microscope (SEM) to monitor morphological changes, Energy Dispersive X-Ray analysis (EDAX) to observe elemental presence over the surface, Fourier Transform Infra-Red (FTIR) spectroscopy to examine chemical changes in the material, Thermo-gravimetric analysis (TGA) to understand the role of filler in aged insulator specimen and loss of Loss of hydrophobicity was measured. Investigations with long duration DC stress reveal material degradation, depolymerization and loss of ATH; this could result in low thermal stability and accelerate the thermal erosion and early failures.