Isotope tracing experimental study on the effects of trace H2O on the over-thermal decomposition of SF6

Abstract

It has been recognized that the gas insulating medium SF6 decomposes when the partial over-thermal fault (POF) occurs inside the equipment. The insulation condition monitoring and fault diagnosis of the equipment can be carried out by utilizing the decomposition characteristics of SF6 under POF. Similar to the discharge decomposition of SF6, trace H2O is an important factor affecting the decomposition of SF6 under POF while its mechanism is not clear yet. In order to investigate the characteristics and micro mechanism of decomposition, the paper combines isotope tracer by adding H218O as a tracer into SF6 gas and carries out experiments. Detecting the concentration and isotope abundance of products by gas chromatography–mass spectrometry, the paper studied the influence of H2O on the production of decomposition products and the specific formation process of CO2, SO2F2, SOF2 and SO2 under the influence of H2O. The research further verified the assumption on formation process of CO2 and SO2 and also brought up with new theory on the formation of SO2F2 and SOF2 based on experimental results.