Movement Patterns of Metallic Particles in a Single Phase Gas Insulated Busduct with Superimposed Lighting and Switching Impulses

Transient over voltages due to lightning and switching surges cause steep build-up of voltage on transmission lines and other electrical apparatus, like circuit breakers, transformers, insulators etc. Therefore it is necessary for the GIS also to withstand such voltages without breakdown of insulation. The system has to be tested under these conditions. Usually the GIS system operates on power frequency. Lightning impulse voltage of 1050 kV and switching impulse voltage of 750 kV superimposed on power frequency voltages of 75 kV, 100 kV and 132 kV are applied to single phase gas insulated busduct and the maximum movement of aluminum, copper and silver particles is determined. The movement patterns are also determined with and without Monte Carlo simulation for movement of particle in axial and radial directions. The results show that there is a sudden jump in the movement at the application of impulse on sine wave. This is because of high magnitude voltage of 1050 kV during 1.2/50 mu sec. Similar movement patterns of reduced maximum movement is observed for switching impulse superimposed on sine wave. The results are presented and analyzed.