Determin the Break-brake Speed of a Half-self Extinguish SF_6 Circuit Breaker Through Analyzing the Pressure Characteristics of Chamber

Taking a 550 kV half-self-extinguishing SF6 circuit breaker as an example,we investigated the impact of changing break-brake velocity on the pressure characteristics of chamber.Firstly,we built up a model of gas characteristic in gas chamber by the first law of thermodynamics and the law of fluid mechanics,by which the pressure characteristics were calculated under different max break-brake velocities of 8.0 m/s,9.0 m/s and 9.7 m/s,respectively.Using the calculation results,we further analyzed the arc-blowing effect and after-zero media recovery of chamber under the different break-brake velocities.According to the interruption performance of the sample breaker,it is proposed that the optimal max break-brake velocity for this breaker is 9.0 m/s;this conclusion is further verified through simulation of the interrupting process of breaker.The research can provide a theoretical basis for setting break-brake velocities of half-self-extinguishing circuit breakers.