Interaction of magnetically blown break arcs with insulating walls in the contact region of interrupters

Both the influence of the material of lateral insulating walls (synergic with the contact material) on arc (im)mobility and the changes of the wall characteristics (flashover voltage, surface resistance, mass loss) caused by temporarily immobile switching arcs were investigated in the contact region of model interrupters. The critical time intervals considered were the time of reduced motion (including initial arc immobility) immediately after contact separation and the delay at the edge of the contact where the arc commutates to the runner. A suitable method was developed to compare the applicability of insulating wall materials to be employed in the contact region of interrupters. Gassing walls may effectively extend the initial time of reduced arc motion rather than making the commutation delay too short for intense arc-wall interaction. However, any wall may accelerate arc commutation by guiding the arc. Both the flashover voltage across the insulating walls and their surface resistance can be reduced by metallization (ceramics) or by carbonization (certain organic materials)