Synthesis of the different technologies for SF6 free medium voltage switchgear

In the framework of the substitution of SF6 in MV switchgear, this paper shows the advantages and drawbacks of the different solutions regarding dielectric withstand and breaking capability. The different gases and technologies of breaking are compared taking into account environmental impacts, toxicity concerns, availability on the market, patent protection, electrical performances, end-of life management and market acceptance. Air or natural gases like N2, O2, CO2can be used as insulating medium. For current breaking, the main manufacturers use vacuum interrupters, a proven technology which generates no by-products. All these natural gases are safe, well-known and required no complex and costly recovery and recycling at end of life of the switchboard if gas is not used for current breaking. Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals that are used throughout society. They are increasingly detected as environmental pollutants and are linked to negative effects on human health. Fluoronitrile, fluoroketone and hydrofluorolefins are PFAS and have cytotoxic, neurotoxic, mutagenic, reprotoxic effects. Some of them are patented for their manufacturing and/or their application. Used as breaking medium, these gases generate toxic by-products and switchgear cannot be operated in an event of leakage leading to a pressure lower than minimum functional pressure as breaking performance is not insured.