Study on the effects of gas pressure and particle size on the liftoff of conducting particles

The existence of the particles has a critical effect on the insulation failures of gas insulated systems. This paper presents the experimental study on the lifting electric field of spherical particles under the different gas pressures in a uniform electric field between two parallel electrodes. The electrode gap was 10 mm. Three sizes of the spherical particles were used. We carried out the experiments in air under pressures of 1, 2 and 3 bar. The experimental results indicated that the particle liftoff depended on the voltage polarity, particle size and pressure. The lifting electric field under positive was higher than negative voltage for all conditions. However, the difference was clear only under 3 bar pressure or for the smallest particle radius (0.4 mm). The lifting electric field increased significantly with increasing size of particles and pressure. It is can be concluded that the effects of particle size and pressure are important for spherical particle liftoff.