Materials Science Forum Vol. 922

Abstract: High temperature caused by copper core would have a certain impact on the performance of XLPE insulation during the long running process of the cable. In this paper, the XLPE/PVC cable running for 17years was investigated by using thermal analysis, microstructure analysis, mechanical property analysis and dielectric properties analysis. The influences of long-term operation for the physical and chemical properties of cable insulation are analyzed by the performance of the insulation material. DSC results indicated that position of shoulder peak would characterize the thermal history of material and express the crystal size distribution of XLPE indirectly. Mechanical property test results showed that effect of long term high temperature would decrease the elongation at break and breaking strength of XLPE. SEM results showed that the effect of long term high temperature increased the average size of crystal and the distribution of the crystal became concentrated, meanwhile it verified the relevant conclusion of DSC.

Abstract: The buried environment of cross-linked polyethylene (XPLE) cable is relatively severe, and some ones are even immersed in water directly. In this paper, an XLPE cable was soaked in foul water to simulate the cable’s actual water area environment, lasting for three years. The water content in the insulation layers of water-soaked cable was measured by infrared spectrometer and moisture analyzer, and the crystal morphology and physicochemical properties of the insulation layers were investigated by differential Scanning Calorimeter (DSC), scanning electron microscopy (SEM) and tensile testing technology. The results showed that a small amount of water did enter into the cable insulation owing to the increasing of hydroxyl (-OH) content, and followed being verified by moisture analyzer. The degree of crystallinity of water-soaked cable insulating material is also increased, and the mechanical properties were deteriorated.