Cross-linked polyethylene (XLPE) is polyethylene (PE) whose chemical structure is modified by cross-linking reaction and has a high allowable operating temperature of 90℃ and excellent electrical properties. As the problem of water tree, which is considered as a biggest weakness, has been improved with the development of manufacturing technology, XLPE is now widely used as an insulation material for power cables of various voltages as well as extra-high voltage.