Investigation on the Reliability of Large Interrupting Capacity SF6 Gas Circuit Breaker With Few Breaks

To improve the reliability of a newly developed puffer-type SF6 gas circuit breaker hydraulically operated, with single- break at 300kV and two-break at 550kV, various investigations are conducted. For the hydraulic operating mechanism, the driving characteristics are studied both by computer estimations and by actual tests. A pilot valve with an opening time of 4ms is developed. Repetitive breaking tests of the line charging current and the terminal fault condition are performed. The circuit breaker displays no problems in breaking this condition. As to the 550kV 2-break circuit breaker, a full-pole breaking test is conducted to verify insulation performance between the end of the breaking chamber and the tank.