Breakdown Characteristics of N₂/O₂ Mixtures at High Pressures in Alternating Non-Uniform Electric Fields

Nitrogen/Oxygen <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathbf{N}_{2}/\mathbf{O}_{2})$</tex> mixtures are with good insulating properties and economic benefits, which are widely used in gas insulation for electric power equipment. The effective ionization coefficient as well as the breakdown voltage of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{N}_{2}/\mathbf{O}_{2}$</tex> mixture is related to the O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> component ratio. In this paper, the breakdown voltages of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{N}_{2}/\mathbf{O}_{2}$</tex> mixtures at high pressures in non-uniform electric fields are investigated. The applicability of Paschen's law in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{N}_{2}/\mathbf{O}_{2}$</tex> mixtures insulation under non-uniform electric fields is analyzed. An empirical formula for the breakdown voltages of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{N}_{2}/\mathbf{O}_{2}$</tex> mixtures is presented. The effect of the O2 component ratio on the breakdown characteristics at high pressures is also analyzed. When the electric field non-uniformity is high, the enhancement effect by the O2 component ratio on breakdown voltage is more significant. The breakdown voltage fluctuation is related to the O2 component ratio and the non-uniformity of electric field.