Diagnosis of degradation condition of silicone rubber using hydrophobic surface analysis

The application of polymer insulator has been expanded in the field of power supply and distribution system all over the world. Compared to the porcelain insulator, however, polymer insulator has been demanded to solve the subjects on a long-term reliability and on a diagnosis techniques in the real application field. Hydrophobicity of polymer surface is one of the degradation indices of polymer insulator material and is usually evaluated by using an image of sprayed water on the sample surface, which is called STRI or spray method. In this study, the effect of parameters to the evaluation of hydrophobicity of silicone rubber are studied. The parameters include surface roughness, measurement temperature, amount of water absorption, weight percent of ATH filler and surface treatment of fillers such as ATH and silica. Hydrophobicity is evaluated by using the image analysis of sprayed water, the dynamic drop test and also the contact angle of a water droplet.