The influence of Cu, Al and Fe free metal particles on the insulating performance of SF6 in C-GIS

Studying the influence of free metal particles on breakdown voltage is important to investigate the insulation performance of SF6 in electric equipment. Under 0.1 MPa pressure and free metal particles defect, this study shows the influence of particle number, gap distance and particle variety on SF6 breakdown voltage on AC power. Experimental results indicate that the breakdown voltage of SF6 decreases as the number of particles increases and eventually stabilizes; A shorter gap distance means a greater effect of free metal particles on the SF6 insulation performance during breakdown; Under the same conditions with copper or aluminum particles, the breakdown voltage of SF6 is approximate and is simultaneously lower than that with iron particles. The electric field force of copper and aluminum particles are close, and larger than that of iron particles, leading to their take-off voltage close and below the iron particles. Metal particles can reduce the reaction barrier of SF6, copper and aluminum particles have similar effects on the reaction barrier of SF6, which are obviously larger than that with iron particles. This study compares the breakdown performance under different numbers of particles, gap distances and varieties of particles. Result shows that copper or aluminum particles in C-GIS affect the insulation performance of SF6 more obviously than that with iron particles.