LW39-126 type outdoor AC HV live tank SF6 circuit breaker is a high performance new type HV SF6 circuit breaker based on sufficient absorbing and digesting advanced technology of foreign SF6 circuit breaker, and according to the requirement of national standard, combining domestic commercial manufacture level and design. This product is used in electric system with 50Hz, 110kV system nominal voltage, and which is main electrical equipment controlled and protected by power station and substation. It can be equipped with CT□ type spring operating mechanism and three-phase mechanical linkage. Inside filling SF6 gas having excellent arc extinction and electrical insulation performance. All seals adopt double-circle O type seal ring, which can prevent leakage efficiently.