Hot gas flow analysis in SF6 gas circuit breaker during the short circuit interruption

Characteristics of the hot gas flow in an SF₆ gas circuit breaker during short-circuit interruption are investigated both experimentally and theoretically, to achieve a more efficient design and to obtain a better way of evaluating circuit-breaker performance. The discharge voltages of small gaps in the actual circuit breaker were measured. The results indicate that the thermodynamic characteristics in the dissociation process of SF₆ molecule affect the behavior of the hot gas flow, even outside of the interrupter chamber. The effect of SF₆ dissociation cannot be neglected even in a wide space in EHV circuit breakers. A program to simulate transient compressible fluid flows was developed. The applicability of this program is proved by the experimental results