A sulfur hexafluoride circuit breaker uses contacts surrounded by sulfur hexafluoride gas to quench the arc. They are most often used for transmission-level voltages and may be incorporated into compact gas-insulated switchgear. In cold climates, supplemental heating or de-rating of the circuit breakers may be required due to liquefaction of the SF6 gas.
- Due to superior arc quenching property of sf6 , such breakers have very short arcing time
- Dielectric strength of sf6 gas is 2 to 3 times that of air, such breakers can interrupt much larger currents.
- Gives noiseless operation due to its closed gas circuit
- Closed gas enclosure keeps the interior dry so that there is no moisture problem
- There is no risk of fire as sf6 is non inflammable
- There are no carbon deposits
- Low maintenance cost, light foundation requirements and minimum auxiliary equipment
- sf6 breakers are totally enclosed and sealed from atmosphere, they are particularly suitable where explosion hazard exists
- sf6 breakers are costly due to high cost of sf6
- sf6 gas has to be reconditioned after every operation of the breaker, additional equipment is
- required for this purpose