Abstract
It has been widely accepted that Gas Insulated Switchgear (GIS) has proven to be reliable, compact and has high availability. However, metallic particles forced to fly and kept in motion in high electric field, can cause partial discharges which lead to a flashover of GIS. Authors have formulated time vs vertical motion equation for a metallic particle on the basis of the statistical analysis of the time-resolved and digitized motion data obtained by a high speed framing video camera, introducing charging-suppress factor η for the coated electrode. Numerical solution of the time-motion equation gives the incidence/departure velocity upon the grounded electrode. Fairly well-agreements have been confirmed between the measured and simulated behavior of the particle’s motion, including its maximum flight height. A metallic wire particle was fixed at various height on a Teflon (PTFE) string tighten radially across the coaxial electrodes. The radius of light emission generated by the partial discharge on both ends of the metallic particle have been observed by an Image-Intesifier. The partial discharge-free allowable maximum flight height and the insulation reliability of GIS have been deduced for various size of the particle as a function of electric field and coating condition, on the grounded electrode combining the simulated particle behavior and observed radius for streamer criteria.
