Effect of Particle Dimensions on Its Movement in Three Phase Gas Insulated Busduct

The gas insulated switchgear (GIS) provides highly reliable, high-safety compact substations by making use of the excellent insulation and the arc extinction performance of SF6 gas. Although SF6 gas offers very excellent insulation characteristics, this very merit may serve disadvantageously, reducing insulation performance in the existence of metallic particles. Internal flashover in SF6 gas, in particular, which can lead to dielectric breakdown accidents, causes a big problem from the viewpoint of GIS reliability. In the present work, simulation has been carried out for particle movement by using the equation of particle motion in an electric field. The effect of various parameters like radii and length of particles on various types of particles for various ac power frequency voltages has been examined and presented. The electric field effect on the particle movement requires the calculation of the electric field which is calculated by using analytical method and Charge Simulation Method (CSM). Metallic contaminations of Cu and Al have been considered for the above study. Typically a GIB of inner and outer dia 55/152mm has been considered. Particles of radii varying from 0.15 to 0.3mm and length from 8mm to 15mm have been used for simulation. Co-efficient of restitution and pressure have been held constant at 0.9 and 0.4 Mpa respectively.