Analysis of infrared spectrum characteristic and variation trend of SF6 PD decomposition

SF₆ decomposition components have a close relationship with the insulation defects in GIS. And the inner insulation state could be evaluated by monitoring the internal gas decomposition components. Fourier transform infrared spectroscopy (FTIR) and gas chromatography (GC) were used to detect the SF₆ partial discharge decomposition products. The sample interval was 12 hours, total discharge time was 96 hours. It´s found that the components were varied in discharge time. The gas were detected by FTIR , such as SOF₂, SO₂F₂, SO₂, SOF₄, SF₄, different gas kinds and the trend of concentration changes can be detected in different periods. The gas kinds which the FTIR detected were more than that of GC. Then, Quantitative analysis was finished by using the absorbance value of each absorption peak. The paper found that there were different components and gas formation rates in different discharge time, so the method could be used for real-time online monitoring of GIS.