Using a self-developed ASTM test system of contact material electrical properties under low voltage (LV), small-capacity, the current-frequency variable and a photoelectric analytical balance, the electric performance comparison experiments and material weighing of silver-based electrical contact materials, such as silver/tungsten and silver/cadmium oxide contact materials, are completed under LV, pure resistive load and small current at 400 Hz/50 Hz. The surface profiles and constituents of silver/tungsten contact material were observed and analyzed by SEM and EDAX. Researches indicate that the form of the contact material arc burnout at 400 Hz is stasis, not an eddy flow style at 50 Hz; meanwhile, the area of the contact burnout at 400 Hz is less than that of 50 Hz, and the local ablation on the surface layer at 400 Hz is more serious. Comparing the capacities of the silver-based contact materials with different second element such as CAgW50, CAgNi10, CAgC4 and CAgCdO15 at 400 Hz, no matter what the performances of arc erosion resistance or welding resistance, it can be found that the capacities of the silver/tungsten material is the best.

An arc model has been applied in this paper to study the fundamental interruption environment of a 550 kV SF6 single-break tank circuit breaker. The full differential model takes into account of all important physical mechanisms and is implemented into a commercial Computational Fluid Dynamics (CFD) package, PHOENICS. The model takes a magneto-hydro-dynamics (MHD) approach and the governing equations are solved using the Finite Volume Method (FVM). Through the simulation, the flow velocity vector and mach number for capacitive current switching and short-circuit current breaking are analyzed, and flow dynamic characteristics are obtained. The simulation can provide helpful reference for the design of 550 kV SF6 single-break tank circuit breaker.