Research about influence of contact burning loss on dielectric recovery characteristic for SF6 circuit breaker

When circuit breaker repeatedly breaks small capacitive current of compensation equipments,serious burning loss phenomenon is placed on the surface of static arc contact, which will lead to changing of contact shape. It may finally result in electric field distortion and adversely affect dielectric recovery characteristic. The mathematical models of electric field and flow field have been established in 126 kV SF₆ circuit breaker. According to gas breakdown criterion of the streamer theory, dielectric recovery characteristic curves in the condition of burning loss angle θ=60° and no-burning loss have been researched. Then electric field distributions in various burning loss angles have been calculated. Results illustrate that seriously impacts critical breakdown voltage,maximal reduction is 130% at the distance of 95 mm. Values of point A are increasing along with larger burning loss angles. Compared with non-burning loss, the value is 7.7 times higher in θ=80° when separation of contact is 17 mm.