Highly Sensitive Photoacoustic Multi-Gas Detection of SF6 Decomposition Components

Abstract The photoacoustic spectroscopy apparatus based on an external cavity quantum cascade laser was employed to simultaneously detect four SF 6 decomposition by-products, i.e., SO 2 F 2 , SOF 2 , CF 4 , and SO 2 for the application in diagnostics of the SF 6 insulation equipment widely used in high-voltage transmission lines. The influence of background gases SF 6 and N 2 with the He addition in different ratios on the SOF 2 photoacoustic signal was investigated, with the pure SF 6 showing the most pronounced enhancement effect on the photoacoustic signal of the target analyte. The limit of detection of SOF 2 in pure SF 6 was estimated by comparing the limits of detection of SOF 2 , CF 4 , and SO 2 in the 95% SF 6 /5% He combination and pure SF 6 . The estimated detection limits for SO 2 F 2 , SOF 2 , CF 4 , and SO 2 were 635.4 ppb, 24.0 ppb, 10.3 ppb, and 97.8 ppb, respectively. Finally, the concentration of each decomposition component in the gas mixture of SO 2 F 2 , SOF 2 , CF 4 , and SO 2 in the 95% SF 6 /5% He background gas was quantified by multiple linear regression.