The condition of the nozzle in a gas chamber is significant for the health of a circuit breaker, especially for high frequency interruption circumstance such as AC filter circuit breaker in HVDC system. However, few methods can assess the ablation state of a nozzle without opening the gas chamber. To solve this issue, this research finds an non-intrusive way to diagnose the nozzle ablation condition. The method is based on tracking or detecting the SF6 decomposed products as the circuit breaker under the test is in operation. Additionally, a SF6 gas chromatography was designed to record and analyse the evolutionary trends of SF6 decomposed products every 20 minutes in a real-time mode. The results show that CF4 can be treated as a characteristic component to reflect the nozzle ablation status. The volume of CF4 was found to highly correlated with the loss of the nozzle materials and the increment of making and breaking energy.

Gas chromatography, Non-intrusive way, Nozzle ablation, SF6 decomposed products, volume of CF4