Movement of particles in compressed SF/sub 6/ GIS with dielectric coated enclosure

In compressed GIS (gas insulated switchgear), the control of wire particle contamination by dielectric coating of enclosure is demonstrated in this paper. Assuming that a particle acquires free charge through a partial discharge, the modeling of particle movement when the inside surface of a horizontal section of GIS/GITL (gas insulated transmission line) enclosure is coated is described. Under an applied 60 Hz ac voltage, the maximum height reached above the enclosure by a particle is much lower for a coated than for an uncoated enclosure. When the applied ac voltage varies, the maximum height reached depends on the magnitude of the applied voltage, phase and velocity at which the particle hits the enclosure. Typical results show that by coating the enclosure, the maximum height reached by a wire particle in a coaxial system can be reduced, thus inhibiting particle movement and minimizing the possibility of insulation breakdown.