Research of Alternative Arc Extinguishing and Insulating Gas Media to SF6

The paper is devoted to comparing the characteristics of SF6 and alternative environmentally friendly mixtures as insulating and arc extinguishing media in high-voltage circuit breakers. It is considered several mixtures based on CO2, N2, air and SF6 as well as their main electrical parameters. A comparative analysis of the dielectric and arc-extinguishing properties of proposed alternative gases is carried out according to the main physical characteristics - the most promising mixture C4F7N/CO2 (Novec 4710) is chosen. An analytical calculation of insulation gaps and gas-dynamic characteristics for SF6 and the alternative chosen is performed. A numerical calculation of the electric fields - “electrostatics” study in COMSOI Multiphysics software for the 110 kV live-tank circuit breaker with SF6 insulation media and the one under study is carried out. It is shown that the proposed alternative based on C4F7N/CO2 is no worse than SF6 as not only an insulating media but also an arc extinguishing one with the minimal global warming potential.