In such breakers, sulphur hexaflouride gas (SF6) is used as the arc quenching medium.
The sulphur hexaflouride gas (SF6) is an electronegative gas and has a strong tendency to absorb free electrons. The contacts of the breaker are opened in a high pressure flow of sulphur hexaflouride (SF6) gas and an arc is struck between them. The gas capture the conducting free electrons in the arc to form relatively immobile negative ions. This loss of conducting electrons in the arc quickly builds up enough insulation strength to extinguish the arc.
The sulphur hexaflouride (SF6) circuit breakers have been found to be very effective for high power and high voltage service.
