Dielectric strength of alternative insulation gases at high pressure in the homogeneous electric field

Abstract

Sulphur hexafluoride (SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> ) is the most common insulation gas in high voltage technology. Besides the excellent insulation properties SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> has the most known global warming potential with a long lifetime in the atmosphere. Alternative insulation gases have only a fraction of the insulation level of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> . The electric strength of gases depends on the gas density and can be increased significantly by using higher pressure. The aspirants were Nitrogen, air and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> -mixtures, with small admixture of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> . The electron affinity of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> increases the dielectric strength of N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> strongly. In general the dielectric strength of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> is three times higher compared to air. Therefore the alternative insulation gases must set under high pressure to get equivalent dielectric strength. With these measurements the electrical breakdown strength of alternative insulation gases in quasi-homogeneous electric fields and the applicability of the Paschen parameters at high pressure have been investigated.