Aging characteristics of 110kV crosslinked polyethylene cable insulation materials

In this paper, the electrical properties and physical and chemical properties of 110kV crosslinked polyethylene cable in service are studied, and the performance degradation principle of cable crosslinked polyethylene main insulation material is obtained through analysis. The performance of XLPE after long operation was measured by means of electrical and physical and chemical analysis. Among them: The measurement range of Fourier transform infrared spectrum is $4 000 \sim 500 cm^{-1}$, the frequency range of broadband dielectric spectrum measurement is $10^{-1}Hz$ to $10^{6}Hz$, and the X-ray diffraction (XRD) method and diffraction Angle range from $10^{o}$ to $30^{o}$, At the same time, the AC breakdown property of crosslinked polyethylene was also studied. The results show that the crystallinity of crosslinked polyethylene cable in service decreases and the crystal structure becomes relaxed. In the process of operation, the chain of crosslinked polyethylene macromolecule breaks, forming a large number of oxygen-containing groups such as carbonyl group. At the same time, the dielectric constant and dielectric loss tangent value of the insulating material are reduced. It is proved that the crystal structure and chemical structure change of the main insulation material under multiple stresses are related to the deterioration of the performance of the main insulation during the natural aging of the running cable.