08-03-2017, 12:10 PM
Sulfur hexafluoride gas (SF6) is an electronegative gas and has a strong tendency to absorb free electrons. The switch contacts open in a high pressure gas flow of sulfur hexafluoride (SF6) and an arc is struck between them. The gas captures the conductive free electrons in the arc to form relatively immobile negative ions. This loss of conducting electrons in the arc quickly accumulates sufficient insulation resistance to extinguish the arc.
Construction of the SF6 circuit breaker
A sulfur hexafluoride circuit breaker (SF6) consists of fixed and movable contacts enclosed in a chamber. The chamber is called the arc interruption chamber containing the sulfur hexafluoride gas (SF6). This chamber is connected to the sulfur hexafluoride gas tank (SF6). A valve mechanism is there to allow the gas to reach the arc interruption chamber. When the switch contacts open, the valve mechanism allows a high pressure sulfur hexafluoride (SF6) gas from the reservoir to flow into the arc interruption chamber.
The fixed contact is a hollow cylindrical current carrying contact equipped with a bow horn. The movable contact is also a hollow cylinder with rectangular holes in the sides. The holes allow the sulfur hexafluoride gas (SF6) to flow through them after flowing along and along the arc. The tips of the fixed contact, the movable contact and the arc horn are coated with material resistant to the copper-tungsten arc. Since sulfur hexafluoride gas (SF6) is expensive, it is reconditioned and recovered using a suitable auxiliary system after each switch operation.