Development of Large-Capacity, SF6 Gas Interruption Chamber and its Application to GIS

The gas density near the nozzle throat in a puffer- type SF6 gas, circuit breaker (GCB) is analyzed, taking into consideration the effect of gas heating by an arc. It is shown that the gas density at the current zero decreases significantly when the nozzle throat causes current clogging. It is confirmed by the experiment that interruption performance is deteriorated with a nozzle having this throat diameter. Based on this investigation, the 300kV-5OkA one- break GCB was developed. The size of the SF6 gas insulated switch- gear (GIS) which adopts the one-break GCB is so sharply reduced that one-bay-on-base transportation becomes possible.