The detection of SF6 decomposition components SO2F2, SOF2 using mid-infrared TDLAS at 6.635 µm and 7.462 µm

Abstract

SO2F2 and SOF2 are the main SF6 decomposition products, and the accurate detection of trace SO2F2 and SOF2 is of great significance to evaluate the internal insulation of the electrical equipment. In general, gas molecules have strong absorption coefficient in the mid-infrared spectral range, which can achieve very low detection limit and has great advantages in the detection of trace gases. In this paper, the quantum cascade lasers at 6.635 µm and 7.462 µm in the mid-infrared band are used as the light source of tunable diode laser absorption spectroscopy (TDLAS) to detect trace SO2F2 and SOF2. The results show that the second harmonic signal peak values of SO2F2 and SOF2 have a good linear relationship with the gas concentration. The linear fits of SO2F2 and SOF2 are excellent at 0.99374 and 0.99785 respectively. The experimental platform has good stability, and the maximum errors are 0.00109 V, 0.00208 V, and 0.00125 V. Allan analysis shows that the detection limit of SO2F2 is 0.1628 μL/L when the integration time is 7.44 s. The detection limit of SOF2 is 0.0167 μL/L at 2.8 s. The research results can provide technical reference and support for the effective detection of SF6 decomposition components.