Cantilever enhanced PA spectroscopy detection for CO decomposition in SF6 equipment

Abstract

The internal decomposition gases of SF6 internal gas insulation equipment is closely related to the insulation state of the equipment. According to the relevant regulations, CO is an important component, and its concentration information can be used as the basis to judge the internal insulation state of SF6 equipment. Gas detection based on photoacoustic spectroscopy is an effective method for current line monitoring. In this study, the distributed feedback semiconductor laser was used as the light source and the interferometer cantilever acoustic sensor was used as the acoustic sensor to set up the photoacoustic spectrum detection device. The CO molecular spectral line of 2.33 $\mu$m was selected as the research object to detect CO by photoacoustic spectroscopy, and the pressure characteristics of the photoacoustic signal is studied. The results show that the detected signal has high stability and a good linear relationship with gas concentration. The minimum detection limit of CO in SF6 gas is 5.1 ppm, and the photoacoustic signal detected by interferometric cantilever excited by CO decreases with the increase of pressure, which is mainly caused by the decline of the response ability of interferometric cantilever with the increase of pressure.