The Effect of Unsymmetrical Material Combination on the Contact and Switching Behavior

Contact materials for electrical power engineering in symmetrical and unsymmetrical combination are investigated with respect to welding resistivity, contact resistance, arc motion, and arc erosion, under special consideration of Ag/C. In combination with Ag/C, the welding resistivity as well as the contact resistance of W/Ag and copper are improved. The arc staying time shows a distinct polarity-dependence in the region investigated (l = 350-1800 A). The erosion is also dependent on the polarity. It coincides with the values that can be calculated from the anode and cathode erosions of the symmetrical combinations.