Review of the decomposition characteristics of eco-friendly insulation gas

As one of the major concerns of climate change, identifying a proper eco-friendly insulation gas for replacing sulphur hexafluoride (SF₆) becomes a prominent research topic in recent years. c-C₄F₈, CF₃I, C₅F₁₀O, C₆F₁₂O and C₄F₇N are some potential alternatives that are proved to have excellent characteristics, including high insulation strengths and low Global Warming Potentials (GWPs). Beyond these key factors, the decomposition products of these alternatives are closely related to the gases' insulation performance, as well as the safety of operators and the compatibility with other materials. In addition, the type and content of decomposition products can be used for fault diagnosis. Therefore, a number of studies were carried out to reveal the decomposition mechanism of these alternative gases, and then to explore the gases' application feasibility and strategy. The recent advances obtained in these studies, including theoretical calculation methods, detection of gas decomposition products, decomposition mechanism are reviewed, and some perspectives for future works are proposed. It is concluded that the phenomenon of solid matter precipitation in c-C₄F₈ and CF₃I gas decomposition cannot be ignored and that more research is needed to reveal the influence of buffer gases, micro-aerobic, micro-water and other impurities on the gas decomposition process.