Development of high voltage VCBs as a candidate for SF6 free switching equipment

This paper describes a brief history leading up to the present situation that VCB became a candidate for SF
6
-free switching equipment is reviewed from the perspective of a Japanese VCB manufacturer. Next, some basic considerations in the development of high-voltage vacuum interrupters, structural innovations of VCBs necessary to withstand the high gas pressure of dry air insulation, and high current interruptions are presented. Finally, test methods for VCBs where conventional methods and standards do not work well are presented.