Influence of electrical and mechanical parameters on contact welding in low power switches

A model switch has been developed to investigate the influence of kinetic parameters, as contact velocity and contact force, on contact welding under conditions prevailing in relays, micro switches etc. Both frequency and intensity of the statistically scattering weld forces increased with increasing arc duration and current. Pre-strike and bounce arcs show identical results under corresponding conditions. Both frequency and intensity of the statistically scattering weld forces initially increased and then decreased with increasing impact velocity. Increasing the static contact force hardly influenced the strength of the primary weld after impact but reduced or prevented weakening of the weld by a following bounce process. The results agree with the predictions of a mathematical model proposed. The configuration of the load circuit determining the actual arc current curve essentially influences the weld force values.