THE EFFECT OF A METALLIC PARTICLE NEAR A SPACER ON FLASHOVER PHENOMENA IN SF(6)

This paper presents a study of the flashover mechanism initiated by me tallic particles in SF6 gas. Using a high-speed Imacon photographic ca mera it was established that a metallic particle near the insulator su rface plays an important role in flashover development. The influence of the particle on flashover development depends on the pressure of th e SF6 gas. At atmospheric pressure, the flashover was always initiated at a point on the particle farthest from the nearest electrode. At hi gh pressures, it was found that breakdown develops from the electrode of relative positive polarity in the form of a leader. The velocity of the discharge crossing the gap increases exponentially when the dista nce between the particle and the insulator surface decreases.