Recent development of high voltage circuit breaker for high voltage power transmission and distribution system

In Japan during the 20th century high voltage transmission and distribution apparatus tremendously advanced and these circuit breakers were center of development. And as a result, 1100 kV SF/sub 6/ gas insulated switchgear (GIS) for AC and also 500 kV DC GIS for DC transmission system have been developed. Also vacuum circuit breaker (VCB) has been actively developed and 168 kV two break VCB and also 100 kA VCB were available. This paper explains these developments.