SF6 circuit breaker is a circuit breaker that uses SF6 gas as the arc extinguishing and insulation medium. It belongs to the same category of air blown circuit breakers as air circuit breakers, with the differences being: ① lower working pressure; ② During the arc blowing process, the gas is not discharged into the atmosphere, but is circulated in a closed system.
1. SF 6 molecules have excellent mixing properties with free electrons. When electrons and SF6 molecules come into contact, they mix almost 100% to form heavy negative ions, which has great value for the ionization and arc extinguishing of the remaining arc column. SF 6 has excellent electronegativity, and its molecules can quickly capture free electrons to form negative ions. The conductivity of these negative ions is very slow, which accelerates the recovery rate of the dielectric strength in the arc gap, thus having good arc extinguishing performance. At a pressure of 1.01 × 10 5 Pa, the arc extinguishing performance of SF 6 is 100 times that of air, and it does not deteriorate after arc extinguishing, making it reusable.
2. The excellent insulation and arc extinguishing performance of SF 6 gas makes SF 6 circuit breaker have the following advantages: strong breaking capacity, suitable for high breaking voltage, allows for more continuous breaking times, suitable for frequent operation, low noise, no fire hazard, low mechanical and electrical wear, etc. It is an excellent "maintenance free" circuit breaker. More and more applications are being made in high-voltage circuits.
There are two commonly used SF 6 circuit breakers: LN1-35 and HB36.