Temperature effect on the insulation performance of SF6/N2 gas mixture at a constant volume

Abstract

With the wide use of gas insulated equipment, alternative gas for SF 6 , such as SF 6 /N 2 mixture, has been put forward to reduce the strong greenhouse effect of SF 6 . Gas insulated equipment usually undergoes a wide temperature range. However, little has been reported about the temperature effect on the properties of gas insulation at a constant volume. This paper has analyzed the change of the gas insulation performance under uniform and non-uniform electric field in different temperatures based on the theory of gas discharge. The gas insulation performance test platform within the scope of low temperature has been set up to study insulation performance of SF 6 /N 2 gas mixture in different temperatures and electric field uniformity under power frequency voltage. The sphere — plate electrode and the rod — plate electrode have been used to simulate different uneven electric fields in the experiment. The test temperature has been controlled at three typical values of −35°C, −18°C and 0°C. Experimental results indicate that the effect of temperature on the properties of gas insulation is similar in the two different uneven electric field. The insulation performance of SF 6 /N 2 gas is significantly reduced under rod-plate electric field compared with sphere-plate electric field. Based on the theory of gas discharge and experimental results, the mechanism of how temperature and uneven degree of electric field affects the properties of SF 6 /N 2 gas insulation has been put forward. The results of this paper provide reference for the possible operation of gas insulated equipment using SF 6 /N 2 gas mixture within the scope of low temperature.