Simulation of the thermal current interruption process of air-break interrupters for future mv application

In recent years, there has been a renewed interest in the potential of air interrupters for application in modern medium voltage distribution networks. This paper reviews the range of stresses to which interrupters could be subjected in such networks and shows that there are several potential areas of application for devices interrupting low currents with low rates of rise of TRV. In a fundamental re-examination of simple low-capacity switching, arc models are utilized to make estimates of the 50 Hz interrupting capacity of atmospheric pressure air arcs at current zero. The possible improvement of interrupting capacity by reduction of the arc time constant is also explored and results compared with recent measurements from the literature. The basis of the arc model is described, and limitations and advantages of the model are discussed. Finally types of air interrupters that could be developed for specific network locations are considered.