Analysis of Decomposition Products by Grease Overdose in SF_6 Circuit Breaker

An abnormal level of CO gas was detected in a 126 kV SF6 circuit breaker when it was being tested.According to the analysis,potential fault has occurred in this circuit breaker.After chemical analysis and experimental research on the source of the CO gas,we disintegrated the circuit breaker in order to check it.Finally we come to conclusion that the fault was caused by the excessive scribbling of lubricating grease.The paper analyses the lubricating grease's influence on the operating characteristics of circuit breaker and the decomposition products of SF6.