Gas density and temperature in thermal volume for self-blast interrupting chambers

Self-blast type interrupting chambers making use of pressure rise due to arc heating have been developed for gas,circuit breakers with lower driving energy. Blowing gas temperature is probably higher in such chambers. Although SF₆ gas is considered to have good arc extinguish capabilities at higher temperature, it is important to investigate blowing temperature to raise arc extinguish efficiency. This paper reports results of the temperature evaluation carried out in a self-blast interrupting chamber model with up to 25kA interrupting current. The peak of gas temperature is about 1000K in a thermal volume of the self-blast chamber. Higher temperature and lower density hot gas from arcing space hardly mixes sufficiently with low temperature gas that remains in the thermal chamber.