Evaluation of Thermal Interruption Capability in SF₆ Gas Circuit Breakers with Re-ignition Voltage and its Application to Experimental Design

Abstract

Thermal interruption characteristics of SF₆ gas circuit breakers were investigated by voltage measurements around current zero. We found that re-ignition peak voltage in the case of an interruption failure could effectively indicate the thermal interruption capability. The efficiency of interruption to puffer pressure could also be evaluated by analyzing the dependency of re-ignition peak voltage on puffer pressure. This technique was applied to experimental design based on the Taguchi method. We successfully optimized the balance of the puffer pressure build-up performance and thermal interruption efficiency to puffer pressure. Finally we demonstrated that a small size research circuit breaker with self-blast interrupter was able to successfully clear the 90% short line fault interruption duty corresponding to 50kA rating in the thermal interruption region.