Development of eco-friendly 72/84 kV vacuum circuit breakers

Vacuum switchgear that uses compressed air as an insulating medium has been developed. This new type of switchgear uses vacuum for an interrupting device and uses compressed air as an insulating medium instead of SF₆. Because of its extraordinary insulating characteristics, SF₆ is widely used in gas-insulated equipment, despite the fact that it is also known to be a significant greenhouse gas and there are many restrictions on its use and handling. Thus there has been a search for a gas to use in place of SF₆. We intend to establish an SF₆-free technology, instead of merely minimizing SF₆ use. To realize an SF₆-free device, we developed two main technologies. One is the combination of molded rubber and compressed air for insulation, and the other is a vacuum interrupter that operates under high-pressure conditions. Combining the insulation abilities of molded rubber and compressed air and a vacuum interrupter that is operational under high-pressure conditions enabled us to create SF₆-free high-voltage switchgear.