What type of medium do SF6 circuit breakers use for insulation?

SF6 circuit breakers utilize sulfur hexafluoride (SF6) gas as both an insulating and interrupting medium. SF6 is a potent electrical insulator and has excellent dielectric properties, which help to prevent electrical arcing and enhance the safety and reliability of high-voltage applications. Its high density allows it to effectively insulate and quench arcs that occur during the interruption of electrical currents, making it particularly useful in environments where space is limited and high insulation levels are necessary.

The gas is capable of handling high voltage levels and is particularly advantageous in terms of thermal stability and inertness, which contributes to its effectiveness in switchgear applications. This choice of medium is what distinguishes SF6 circuit breakers from those that use air, vacuum, or silicone, which do not provide the same level of performance as SF6.