Modelling and Analysis of Metallic Particle Movement in a Common Enclosure Gib With Electromagnetic Field

Abstract

Compressed gas-insulated substations (GIS) consist basically of a conductor supported on insulators inside an enclosure, which is filled with sulphur hexafluoride gas (SF6) . The voltage withstand capability of SF 6 bus duct is strongly dependent on field perturbations, such as those caused by conductor surface imperfections and by conducting particle contaminants. The contaminants can be produced by abrasion between components during assembly or operations. These particles can either be free to move in the GIS bus or they may stick either to an energized electrode or to an insulator surface. If a metallic particle crosses the gap and comes into contact with the inner electrode or if a metallic particle adheres to the inner conductor, the particle will act as a protrusion on the surface of the electrode. A study of CIGRE group suggests that 20% of failure in GIS is due to the existence of various metallic contaminations in the form of loose particles. The presence of contamination can therefore be a problem with GISs operating at high fields. If the effects of these particles could be eliminated, then this would improve the reliability of compressed GIS. It would also offer the possibility of operating at higher fields to affect a potential reduction in the GIS size with subsequent savings in the cost of manufacture and installation. The purpose of this paper is to develop techniques, which will formulate the basic equations that will govern the movement of metallic particles like aluminium and copper in a three-phase gas-insulated bus duct. The simulation also considers the electromagnetic field effect on particle movement and the results have been presented and analyzed.