Quantitative analysis of SO, HS and CS mixed gases based on ultraviolet differential absorption spectrometry.

SO, HS and CS are the decomposition components of insulating gas SF. The detection of these gases is significant for the online monitoring and fault diagnosis of SF electrical equipment. In this study, an ultraviolet differential optical absorption spectrometry (UV-DOAS) platform for detecting the concentration of SO, HS and CS mixed gases was established and a quantitatively detecting method was proposed. Firstly, the concentration of SO was calculated by the spectrum data at 300 nm band. Then the gas mixture spectra of HS and CS at 200 nm band were obtained after linear deduction of SO spectrum. By wavelet extraction and fourier transform, the spectral information of HS and CS was separated and the concentrations of the two gases were calculated. The method can detect the concentrations of SO (1-20 ppm), HS (1-20 ppm) and CS (0.01-2 ppm) ternary gas mixture and the detection limits of SO, HS and CS are 0.44 ppm, 0.49 ppm and 3.23 ppb. This method has good detection sensitivity and high detection precision, which is suitable for the on-line monitoring of SF gas insulated equipment.