In order to understand the reasons of 750 k V SF6 tank circuit breaker flashover fault and to accumulate expe-rience in failure analysis

in view of a 750 k V SF6 tank circuit breaker failure in Xinjiang Hami 750 k V substa-tion

by the means of disintegration of the scene view

returned to the factory for disintegration check

product quality tracing

and test methods

the cause of the failure of the circuit breaker is found finally. It is confirmed that the circuit breaker fault is caused by the fracture parallel capacitor due to its dielectric loss is too high

which leads capacitor to explosion

and then leads circuit breaker fracture to breakdown

eventually the flashover has happened. The circuit breaker failure analysis provides a reference experience and ideas for the troubleshooting and operational security of 750 k V circuit breaker in future.