| Popis: |
Presence of water droplets on a polluted outdoor high voltage insulator surface modifiesthe electric field flux and the equipotential distribution along the insulator surface. Thewater droplet may appear in different forms and sizes. The form is defined, here, by theangle shape between the water droplet surface and that of the insulator, which is keptconstant at 90 degrees. The droplet size is specified by the diameter. The water dropletmay measure from less than 90 degrees (hydrophilic) up to greater than 90 degrees(hydrophobic), depending on the properties of insulator surface.The present work describes a detailed numerical computation of the electric field andthe potential distribution in the surroundings of water droplet on a polluted insulatorsurface. The computations are carried out using the Femlab package 3.1, which is basedon the finite element method.The parameters used in the numerical analysis are the size of the water droplet and thepollution layer permittivity which describes the possible wetting conditions of the layer(i.e. clean, semi-wetted, and fully-wetted polymer surface). Detailed plots of thepotential and field distribution in the inter electrode space, with and without thepresence of a water droplet, were generated. The results showed that the electric fieldclose to the water droplet tends to be higher as the diameter of the droplet increases, andlower as the relative permittivity of the pollution layer increases. |
