Electrical insulating characteristics of polymeric materials under wetting and contaminated conditions-results of CIGRE round robin test

Polymer insulators are considered to have a higher withstand voltage under contaminated conditions compared with porcelain or glass ones. In the case of polymer insulators with silicone rubber (SIR) sheds, it is said that hydrophobicity of the surface is maintained for a long period because of migration of low molecular weight silicone from the bulk of SIR to the surface. However, the characteristics of polymer insulators after a long period of use have not been well evaluated. Fourth (4th) round robin test (RRT) has been conducted under the direction of CIGRE WG15.04 in order to investigate the long term reliability of polymeric materials under wet and contaminated conditions. Seven institutes participated including us to the RRT in the world. This paper reports the results of the RRT of our group.