Infrared Spectrum Analysis and Quantitative Detection of SF6 Characteristic Decomposition Components SO2F2 and SOF2

SO₂F₂ and SOF₂ are important characteristic decomposition components of SF₆. Accurate detection of these two gases is helpful for fault diagnosis of gas-insulated switchgear (GIS). In this article, the infrared characteristic peaks of SO₂F₂ and SOF₂ were obtained by comparing the simulation and experimental infrared spectrum. Then, cross interference analysis was performed with SF₆ characteristic components such as H₂S, SO₂, CO, and SF₆ background gas to determine the appropriate detection bands for SO₂F₂ and SOF₂. Tunable diode laser absorption spectroscopy (TDLAS) experiment platform was built based on quantum cascade laser with center wavelength at 1506.4 and 1340.2 cm⁻¹. The concentration of SO₂F₂ and SOF₂ is detected through this platform. And the concentration information of gas is deduced by detecting the voltage value of second harmonic signal. The experimental results show that, for SO₂F₂ gas between 1.01 and 19.88 ppm, the $R^{2}$ is 0.989 and the maximum relative error is 2.044%. For SOF₂ gas between 1.03 and 9.00 ppm, the ${R}^{{2}}$ is 0.992 and the maximum relative error is 0.728%. SO₂ gas may cause weak interference to SOF₂ detection, which has some regularities, and the interference can be eliminated by selecting the appropriate SOF₂ fitting linear equation. The research results provide a feasible scheme for the quantitative detection of SO₂F₂ and SOF₂ gases.