Simulation and motion analysis of spherical free conducting particle between coaxial electrodes

The trend of development of Gas Insulated System (GIS) recently includes: miniaturization, intelligentization and high reliability. This needs a higher insulation performance of GIS. Free conducting particle in GIS is a main reason that causes the degradation of GIS insulation. Free conducting particle will bring a high risk to GIS insulation when it approaches to the high voltage conductor or reaches the disc-type insulator surface. Particle in radial non-uniform electrical field is apt to move along the radial direction in GIS, and probably moves into the high insulation risk region. According to the distribution of the electrical field between coaxial electrode systems, the dynamic model of spherical particle in axial non-uniform electrical field under AC voltage is amended. The motion phenomenon of particle is explained by solving the dynamic equations. Gravitational force, Coulomb force, electrical gradient force and gas viscous force are considered. Improving the applied voltage can increase the motion distance in vertical direction. The criterion can explain the incremental quantity of the motion onset voltage of particle in uniform field under AC voltage than it under DC voltage. Observations indicate that voltage exerts an incremental effect on maximum height. By analyzing improved dynamic model of spherical particle, another novel criterion to judge the penetration of the motion of spherical particle in uniform field under AC voltage is brought forward, as well.