Influence of PTFE ablation on the performance of high voltage self-blast circuit breaker

Self-blast circuit breakers utilize the energy dissipated by the arc itself to create the required conditions for arc quenching during the current zero. The arc energy induces ablation of the PTFE nozzle. Ablated nozzle shape and SF₆-PTFE mixture vapor affect the performance of a self-blast circuit breaker. After a number of tests nozzle in circuit breaker is disassembled, and ablation of the nozzle is investigated precisely. Using computational fluid dynamics (CFD), temperature, pressure, velocity and electric fields inside the circuit breaker are calculated. Performance of ablated nozzle shape and different amount of PTFE ablation mass flux is compared with original model using CFD code.