Measurement of Darcy and Forchheimer Coefficients for Silica Sand Beads

Experimental study of HBC fuses working at short and medium pre-arcing times

“…Due to the energy supply the metallic plus air plasma interacts with the surrounding granular silica sand whose morphometric properties are carefully checked. In fact, the main morphometric properties-granulometry, porosity and the induced drag coefficients of the porous medium [4]strongly influence the evolution of the main plasma properties, such as the temperature, the electron density and the pressure [5][6][7][8]. Thus the plasma becomes a silica plus silver plasma at the early beginning of the next stage, namely, the arcing stage.…”

Electric fuses operation, a review: 1. Pre-arcing period

“…If the porosity or volume of the void space is kept constant one understands that the characteristic length of the pore will vary with the mean equivalent diameter of the silica sand grains. For example in the case of sphere bead instead of silica sand grains bead with a porosity  0.4 [24], the equivalent pore diameter is found  116 µm for 275 µm-mean diameter spheres,  172 µm for 375 µm-mean diameter spheres and  2086 µm for 5 mm-mean diameter spheres (the granulometric distribution around the central quoted value being different for each mean granulometry). The void space volume depends directly on the grain size which is an industrial parameter and can modify the vaporization temperature of silver and silica thus changing the plasma composition.…”