Effect of mobile conducting particles on the electrical strength of the insulation system of SF6 insulated switchgear

The authors present data obtained from tests conducted on an SF ₆ GIS (gas-insulated switchgear) model, 123 kV, having coaxial cylinders of 240/80-mm diameter in the presence of mobile particles. In the case of a vertical GIS construction and in the presence of conducting particles, a great hazard to the insulation is shown to occur when overvoltages appear in service. There is a wide range of imminent particles since heavy and light particles are included. The presence of conducting particles in the case of a conic spacer insulator also causes a hazard to insulation due to overvoltages appearing in service. The detection of particles left after final assembly on site and of those located on the spacer insulators which were tested in 123-kV GIS is possible using tests with applied 185 kV AC voltage and tests with impulse voltage at 80% basic insulation level