Diagnosis of Degradation Condition of Polymer Material 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. In this study, dielectric measurement and image analysis are used to evaluate the hydrophobic condition and, therefore, the degradation condition of polymer surface. Using image data analysis of these water droplets, STRI´s hydrophobicity class, HC from 1 to 7, is evaluated automatically. The water droplets on the sample surface are digitized and the image indexes such as size and shape factor of the droplets were evaluated. After this evaluation, 3D mapping technique is used to evaluate the HC value. Comparing of these results can define the small changes in the degradation condition of hydrophobicity of polymer insulator more accurately.