Transient Arc Characteristic of a Commutation Switch Utilizing High Velocity Contact Separation

Abstract

Commutation circuits are commonly used for low on state resistance and high current interruption capability if this can not be achieved by a single device or single current switching path. In case of fault detection, a very fast commutation of the current from the low-impedance main current path into the parallel high-current interrupting path is necessary. For single usage applications a low-cost approach is the utilization of a pyrotechnical switch in the low-impedance path. Compared to other electromechanical switches, those switches provide very high velocity of contact separation and thus a fast arc voltage rise with short commutation times. Here, measurements of the contact movement of a pyrotechnical switch were carried out using optical high speed imaging and an arc elongation up to 100ms−1 was calculated. From this, transient arc characteristics were measured in a simplified commutation network during the period until current zero in the low-impedance main current path.