Abstract
In order to evaluate thermal interruption capability of gas circuit breaker, we consider that mass flow rate in nozzle throat at around current zero points is the most effective parameter, because it is closely related to the cooling capability of arc. In thermal puffer type gas circuit breaker, the mass flow rates depend not only on puffer pressure but also on gas passage structure. So using a calculation program of gas blast characteristics taking both arc energy and ablation gas into consideration, the relations between the mass flow rate at current zero points and gas passage structure were investigated. As the results, we found that shorter gas passage length greatly increases the mass flow rate at current zero points, although it does not influence puffer pressure formation so much. We also found that optimum cross sectional area of gas passage is a bit smaller than that of nozzle throat. If thermal interruption limit were determined by mass flow rate at current zero points, the shorter gas passage length and optimized cross section area will increase the SLF interruption capability of thermal puffer type gas circuit breaker.
This paper describes the detail of the results of simulations and discussions.
