Corona studies on polymeric insulator samples used in high voltage transmission

The use of polymeric insulators for overhead transmission and distribution has increased over ceramic insulators in recent years. However, polymer insulators are subjected to degradation due to corona among many other problems. This is further enhanced by the presence of moisture in air as also by acid rain. In this work degradation of polymer insulators is studied by subjecting to corona under conditions of normal air, normal fog and acidic fog separately. The extent of degradation is determined by hydrophobicity, SEM (Scanning Electron Microscope) images and tensile strength measurements. Corona degradation in presence of fog is found to be more severe than that in the presence of normal air.