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

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 H₂ ¹⁸O 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. (paper)