Electrical contact phenomena during impact

The authors outline the theory of impact as it applies to electrical contacts. The concept of the coefficient of restitution is evaluated as a means of modeling the events at impact. The events occurring during the impact of electrical contacts are vital to the long-term reliability of the contacts; so design parameters are considered in terms of their influence upon the dynamics of impact and bounce. Experimental studies are presented which include the measurement of impact forces, impact time, and both current and voltage characteristics. The influence of preimpact arcing is evaluated in the medium current range, and is shown to have an effect on the events occurring during the first impact. A mathematical model is proposed for electrical contact bounce, but it is shown that reducing the arcing may not always reduce contact wear.<>