POWL-VAC CIRCUIT BREAKER n nTypical POWL-VAC one high feeder rated kV 2000-amp main bus, 750 MVA. Photograph illustrates typical metering and relaying with ample space for field incoming control wire.POWL-VAC switchgear features optional MOC, TOC and kirk key interlocking provisions. n nThe vacuum switching surge phenomenon has been clarified and problems in practical applications have been studied and solved.