Detection of Decomposition Products of SF6 Gas Based on Gas Chromatography and Optical Cavity Detection and Its Field Application

The research on the new detection technology of SF6 gas decomposition products is carried out, the detection test of gas chromatography technology suitable for the analysis of trace substances in SF6 gas is carried out, and the gas path system design, Detector Optimization and chromatographic column selection scheme of TCD and FPD parallel process are put forward, so as to realize injection analysis of characteristic components of decomposition products. Using the laser detection method, the HF gas detection platform is designed, and the HF gas detection device is developed. The detection limit is less than 0.5l/l. Using the tunable diode laser absorption spectroscopy technology, 1278nm band is selected as characteristic spectrum line, butterfly DFB semiconductor laser with the cold stack is selected, and the standard gas reference module is designed. Sapphire transparent window and M400 Monel alloy tube are selected as the materials of gas chamber in the optical path cell. The HF gas detection device is developed, and the detection limit is less than 0.5μL/L. The characteristic components and content variation law of SF6 gas decomposition products identified by typical defect types of high-voltage bushing are proposed: for the breaking defects such as excessive air and moisture content of SF6 gas in circuit breaker, insufficient air pressure in bushing composite insulator, excessive grease coating and central conductor contact ablation, the characteristic components of decomposition products are mainly SO2, CO and CO2. When the high-voltage casing body has defects, the HF content increases rapidly. Main decomposition products produced by discharge are SOF2, SO2F2 and SO2. In case of the abnormal heating defects of the metal connection and insulation in the equipment, reaction temperature between material and SF6 gas is lower than 300°C, characteristic components of decomposition products produced by abnormal heating of metal connection are SO2, and the characteristic components of decomposition products produced by abnormal heating of insulation are SO2, H2S, CO and CO2.