Simulation and Experiment of SF₆/N₂ Mixed Gas Distribution in High Vertical Drop GIL

Dielectric breakdown of a vertical Gas insulated transmission line (GIL) caused by demixing of the mixture of SF
₆
/N
₂
is studied by both theoretical simulation and the experimental measure. The mechanism and the threshhold of the demixing is addressed quantitatively. The potential risk of the segregation of the molecules by forming dimer or trimer under the high voltage is excluded by the quantum mechanics simulation in microscopic scale and the molecular simulation in mesoscopic scale. In macroscopic scale, the distribution of the mixture depending on the length of the tube is computed by the statistical physics quantitatively.