Study on pyrolysis characteristics of high voltage power cable Polyvinyl chloride outer sheath based on Fourier transform infrared spectrometer

In order to clarify the pyrolysis characteristics of the Polyvinyl chloride outer sheath under local overheating, a pyrolysis experiment platform for the outer sheath of high- voltage cables was built. And the initial decomposition temperature of the outer sheath was judged with temperature as an independent variable and characteristic gas content as a reference value. In particular, the solid oil between the surface coating of the outer sheath surface and the armor was cleaned with acetone to avoid interference with the experiment before the experiment. First of all, this study uses high-purity nitrogen as the background gas, which is scanned by infrared spectrometer to ensure that the gas in the heating tank was completely replaced with nitrogen. Finally, put the cleaned sample into heating tank, select HCl as the characteristic gas for pyrolysis, and use an infrared spectrometer to collect the characteristic gas content in the range of 100 ~ 130°C by controlling the temperature. So the initial temperature and optimum decomposition temperature of the HCl characteristic gas formed by the decomposition of the outer sheath of polyvinyl chloride were determined. Through the above research, the correlation between the HCl gas content and the local overheating fault of the outer sheath is obtained, and it laid the experimental foundation for the final construction of the local overheating diagnosis method of power cables based on the characteristic components of polyvinyl chloride pyrolysis.