Influence of the shape, number, position and dimensions of conductive particles within inter-electrode gap on dc and pulse breakdown voltage value of SF6 and N2 mixture

The aim of this paper is to determine how the shape, number, position and dimensions of the conductive particles produced during switching operations influence the dielectric strength of the gas-filled switches insulated under pressure which are in the state of open contacts. To this end we have developed a numerical program that makes it possible to calculate dc values of the breakdown voltage of bi-electrode gas-filled system in which conductive particles of defined shape and dimensions are present in inter-electrode gap. The calculation results are empirically tested (and verified) in controlled laboratory conditions. Based on the obtained results suggestions are made as to how to extend the life span of gas-insulated circuit breakers using SF6 and N2 mixture instead of pure SF6.