Behavioural study of SF6 replacement gases in power transmission systems

High voltage circuit breakers utilize the very nature of rapid changing resistance of an electric arc to realize circuit interruption. High speed gas flow in a supersonic nozzle is normally used to ensure arc quenching in the chamber. The thermodynamic and electrical behaviors of arcs burning in such nozzles are closely related to the properties of the gaseous medium. SF₆ is currently used as working medium because of its excellent dielectric properties. However SF₆ is a strong greenhouse gas with a life time of 3200 years and a global warming potential (GWP) of 22800 in comparison with CO₂ which has a GWP of 1.0¹. The replacement of SF₆ with a more environmentally friendly gas is becoming an increasingly interesting research topic² and practically important issue for power equipment manufacturers and network operators³.