In-situ assessment of composite insulator surface condition

Chemical surface analysis techniques have been applied to investigate ageing of HV composite insulators. A number of simple non-invasive techniques have been developed for sampling shed material of insulators in power systems. FTIR analysis of EPDM insulators has produced a measure of surface oxidation that indicates that oxidation is accelerated by the combination of electric field and UV. No such effects were observed from FTIR analysis of silicone rubber insulators, but it is possible that analysis of the silicone content of the surfaces using XPS and TGA will be useful techniques in determining the amount of LMW material remaining in the insulator. Further work is progressing to systematically examine how controlled amounts of UV and surface discharging affect surface condition as measured by these techniques. The further question of how the surface condition affects surface discharging also remains to be answered.