Investigation of technology for developing large capacity and compact size GCB

New effective technologies to increase the interruption capacity and to the reduce size of a gas-insulated circuit breaker (GCB) are shown. One is the adoption of a new nozzle shape that improves the cooling of the arc. The other is the investigation of hot gas diffusion in the exhaust cylinder related to the dielectric strength recovery after the current interruption. It is shown that these technologies are useful for increasing the interrupting current from 50 kA to 63 kA.