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Gases for Electrical Insulation and Arc Interruption: Possible Present and Future Alternatives to Pure SF6



Loucas G. Christophorou, James K. Olthoff, David S. Green


The electric power industry's preferred gaseous dielectric (besides air), sulfur hexafluoride (SF6) has been shown to be a greenhouse gas. In this report we provide information that is useful in identifying possible replacement gases, in the event that replacement gases are deemed a reasonable approach to reducing the use of SF6 in high voltage electrical equipment. The report focuses on the properties of SF6 as a dielectric gas and on the data available for possible alternatives to pure SF6 (i.e., SF6 alone). On the basis of published studies and consultation with experts in the field it was attempted to identify alternative dielectric gases to pure SF6 for possible immediate or future use in existing or modified electrical equipment. The possible alternative gases are discussed as three separate groups: (I) mixtures of SF6 and nitrogen for which a large amount of research results are available; (ii) gases and mixtures (e.g., pure N2, low concentrations of SF6 in N2, and SF6-He mixtures) for which a smaller yet significant amount of data are available; and (iii) potential gases for which little experimental data are available.
Technical Note (NIST TN) - 1425
Report Number


gaseous dielectrics, gas mixtures, gas recycling, global warming, nitrogen, SF6, SF6-N2 mixtures, sulfur hexafluoride


Christophorou, L. , Olthoff, J. and Green, D. (1997), Gases for Electrical Insulation and Arc Interruption: Possible Present and Future Alternatives to Pure SF<sub>6</sub>, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed May 18, 2024)


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Created October 31, 1997, Updated October 12, 2021