Processes on Contacts and Thermal State of Contact Surfaces in AMF-Contact Systems of Medium-Voltage Vacuum Interrupters When Switching the Limiting Current: A Review

At the beginning, this article provides an overview of the results of previous physical investigations of the processes determining the limiting interrupted current of ac vacuum circuit breaker. The concepts formed on the basis of these results are formulated. Further, this article provides an overview of the results of modern research of axial magnetic field (AMF)-contact systems for medium-voltage vacuum interrupters (VIs). New technical tools developed in the last decades have allowed progress in understanding processes at the electrodes during the arc burning and determining the thermal state of the electrodes after arc extinction. The results obtained in a number of modern works allowed us to supplement and clarify previous hypotheses. It is shown that in medium-voltage VIs process of the gap breakdown immediately after current zero, processes on electrodes, namely, the dynamics of the electrode melt, play an important role.