Accelerated thermal aging of three-core power cable thermal aging rule and mechanism of typical insulating materials

10kV XLPE distribution cables have a large space span and complex operating environment, and are prone to aging after long-term operation, threatening the safety of power grid operation. Most of them are three-core cables. Currently, research on cable aging mainly focuses on single-core cables, while there are few studies on thermal aging of three-core cables. Through simulation and test, it is found that the thermal aging of three-core cable is quite different from that of single-core cable. In this paper, the internal heating accelerated thermal aging platform of three-core cable was built, and the inner and outer sheath, metal shielding layer and semi-conductive layer were observed by Scanning Electron Microscope (SEM). Energy Dispersive Spectrum (EDS) was used to deduce the composition of elements and the chemical reaction in the aging process. Fourier Transform Infrared Spectroscopy (FTIR) was used to observe the changes of the characteristic peaks of groups in the thermal aging process. Finally, the physical and chemical characteristics of each part in the thermal aging process of three-core cable are deduced, and the thermal aging of three-core cable can not be simply equivalent with single-core cable.