Analytical Prediction of High Pressure SF<inf>6</inf> Gas Breakdown Strength in a Spark Gap Switch

Abstract

It is difficult to predict or measure breakdown strength of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas, especially in high pressure range. It is even hard to find reference data of the high pressure SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> breakdown strength. We tried analytically to compute the breakdown strength of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas above 3 bar-cm range in a spark gap switch. The computed result is compared with several published experimental data and showed good agreement for different geometries with a wide range of pd (pressure time gap distance) and field enhancement factor (FEF) to a great extent. For the computation, J.C. Martin's modified field formula as well as Kuffel et al's formula for breakdown in SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas is adopted. We will discuss the analytical prediction method of the high pressure SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> breakdown strength and the compared result with experimental data.