Downstream Region Influence on Interruption Ability of HV SF₆-Blast Interrupters with Synchronous Gas Injection

One of the main approaches to modernization of the HV gas-blast interrupters is to increase the rated voltage and rated current per one break. The downstream region of the profiled nozzle affects the interruption ability with an increase of the rated voltage. The increase in the rated voltage calls for some additional drive work to diverge the arcing contacts and increase the diameter of the insulating nozzle. Therefore, the interruption ability decreases due to the pressure gradient degradation, turbulence attenuation and others processes in the downstream region. An additional synchronous (controlled) gas injection in the vicinity of current zero from the channel at the nozzle throat area is one of the possible ways to solve the problem providing effective use of arc quenching medium. The channel connects the pressure storage volume (puffer volume) and the nozzle throat area. This paper assesses the synchronous gas injection influence at different input angles into the nozzle throat region using numerical simulation. The Hartmann principle turns the downstream contact with cavity into a resonator. SF₆ is considered as an arc quenching medium. The distribution of gas-dynamic parameters in the downstream region is varied, additional flow turbulence is provided, the interruption ability is increased.