The experimental investigation of the effect of circuit parameters on erosion dynamics in silver contacts in air

The paper discusses erosion dynamics in electrical contacts during the development and evolution of free burning, transient arcs in electrical switches, operating in air at atmospheric pressure. The paper studies the transition between anodic and cathodic stages of the arc and experimentally investigates the influence of supply current, voltage, time constant of the circuit and opening velocity on erosion dynamics and material transfer direction during the process of electrical contact break. The curves of erosion dynamics obtained with high resolution for contacts of pure silver for different opening parameters. Variations of supply current, voltage, inductance and opening velocity allow the authors to establish the dependence between the above parameters and erosion behaviour. Special computer controlled equipment was employed to provide opening with a constant velocity and to maintain the linear dependence between opening time and velocity. Uniform opening, together with the "purity" of the contact material (silver) make this experimental study useful both for real applications and for comparison with theoretical simulations of contact erosion.