SF6, globally used as insulation gas in the High Voltage gas insulated switchgear (GIS), has an extremely high Global Warming Potential (GWP) and should be replaced in the perspective of more eco-friendly apparatus. One of the possible SF6 alternatives that emerged in recent times is a fluoronitrile (FN), NovecTM 4710, based mixture. As this mixture aims to replace SF6 in the future SF6 free HVDC GIS, its behavior in HVDC GIS should be investigated. In this context the conduction behavior of 6% FN and 94% CO2 mixture and SF6, as comparison, have been investigated under high electric fields (up to 20 kV/mm) in a uniform electric field configuration. The results show that the leakage current though investigated gases depends on the polarity of the DC voltage and the roughness of the electrode. Moreover a difference in term of leakage current is observed for the studied fluoronitrile mixture compared to SF6 although they have the same equivalent dielectric strength.
C. Toigo, T. Vu-Cong, F. Jacquier, A. Girodet
Presented at ICD 2020