Influence of Gas Density and Segregation on the Dielectric Strength of Gas Mixtures
Th. Hammer
Siemens AG, CT RTC PET, Germany
Abstract- Gas mixtures are widely used for electrical insulation in medium voltage and high voltage facilities. The dielectric strength of the gaseous electrical insulation depends substantially on mass density and composition of the gas mixture. Thus the influence of physical processes which could cause a change in gas density or segregation of components of the mixture was investigated exemplary for SF6-N2-mixtures by means of model calculations. The dielectric strength was assessed applying numerical simulation of the critical reduced electric field strength and scaling laws for dielectric breakdown. The phenomena investigated were baro-diffusion, thermo-diffusion, electrophoresis, and electrohydrodynamics as well as thermal convection counteracting these processes.
Keywords-Gas insulation, segregation, convection, electro-hydrodynamics