Investigation of interrupting chamber performance

The interrupting chamber for 550kV 1-break gas circuit breaker (GCB) was developed. To cope with voltages and interrupting capacities of nearly double per break compared with 2-break GCBs, the shape of the interrupting chamber was optimized, and an interrupting chamber scheme using arc energy was employed. Small-current interrupting performance was improved by selecting a nozzle shape with pressure fluctuations due to a supersonic flow at the downstream side of the nozzle and dielectric recovery characteristics taken into account. By employing an interrupting chamber scheme utilizing arc energy, the opening speed is increased by minimizing the reaction due to pressure rises in the puffer chamber in small-current interruptions or the pressure is sharply raised due to the effect of arc energy in large-current interruptions. The nozzle shape is also optimized for a large-current interruption by improving the efficiency of treating hot gas.