Condition Assessment on Arc Nozzle of High Voltage Circuit Breaker Through SF6 Decomposition Products

摘要

The condition of arc 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 breakers 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 proposes an non-intrusive way to diagnose the nozzle ablation condition. The method is based on tracking the SF6 decomposed products as the circuit breaker under test is in operation. Additionally, a SF6 gas chromatography was designed to record and analyse the changing 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 CF4 content is found to highly correlated with the loss of the nozzle materials and the increment of making and breaking energy.