Effect of Various Design Parameters on the Movement of Metallic Particles in a Three Phase Common Enclosure Gas Insulated Busduct

Metallic particle contamination in a compressed gas insulated busduct (GIB) or system (GIS) may lower the corona onset and breakdown voltage of the system considerably. These particles move randomly in a horizontally mounted GIB system due to the electric field, and this movement plays a crucial role in determining the insulation behavior of gas insulated substations. Under 50-Hz AC voltage, the particle motion is complex, and under appropriate conditions, the particle may cross the gaseous gap from the low-field region near the outer enclosure to the high-field region near the central conductor. For the commonly encountered size of metallic particles in practical gas insulated systems, such a crossing of the gaseous gap takes several cycles of the 50-Hz voltage. In order to determine the particle trajectories in a three-phase common enclosure gas insulated busduct (GIB) an outer enclosure of diameter 500 mm and inner conductors of diameters 64 mm spaced equilaterally are considered. Wire like particles of aluminum, copper as well as silver of a fixed geometry has been considered to be present on enclosure surface of a three-phase busduct. Simulation is carried out for movement of metallic particles in a three-phase busduct with reduced phase conductor diameter with a view to obtain optimum size of conductor for reliable operation. The work is carried out by reducing the original diameter of the conductor from 64 mm to 54 mm in steps of 5 mm.