Cross-linked polyethylene (XLPE) is a widely used insulation material for medium- and high-voltage power cables, low-voltage cables, building wiring, and special-purpose cables. It is produced by chemically or physically cross-linking polyethylene chains, transforming a thermoplastic polymer into a thermoset material. This cross-linking process greatly improves the thermal, mechanical, and electrical properties of the base polymer, making XLPE suitable for demanding environments and long-term service.In electrical applications, XLPE insulation offers excellent dielectric strength and low dielectric loss, which helps ensure efficient power transmission and distribution. Its stable electrical properties over a broad temperature range contribute to reliability under varying load and environmental conditions. XLPE also demonstrates good resistance to partial discharge, which is critical for the long life of medium- and high-voltage cable systems.Thermal performance is one of the major advantages of XLPE. The cross-linked structure allows continuous operating temperatures up to around 90 °C, with higher short-circuit temperature capabilities for limited durations. Compared with conventional PVC insulation, XLPE can withstand higher conductor temperatures without significant deformation or loss of mechanical integrity. This property supports increased current-carrying capacity and more compact cable designs.Mechanically, XLPE insulation exhibits good tensile strength, abrasion resistance, and flexibility. These characteristics facilitate installation in ducts, trays, and underground systems, and help the cable withstand pulling forces during laying. The material retains its properties over time, resisting cracking and stress under typical mechanical loads. Its resistance to moisture and many chemicals further enhances durability, especially in buried and industrial installations.XLPE also shows good environmental resistance. It does not contain plasticizers or halogens, so it does not release corrosive halogen gases during combustion. When combined with suitable flame-retardant compounds in cable design, it can contribute to lower smoke and toxicity characteristics compared with some traditional insulation materials. This is particularly important for installations in public buildings, tunnels, and confined spaces where fire safety and smoke control are critical.Processing methods for XLPE include peroxide cross-linking, silane (moisture-cure) cross-linking, and radiation cross-linking. Each method influences the final material structure, cleanliness, and performance. For power cables, cleanliness of the XLPE compound and precise control of the cross-linking process are essential to minimize impurities and defects that could initiate electrical treeing or partial discharges.In summary, XLPE insulation combines strong electrical performance, high thermal endurance, good mechanical properties, and robust environmental resistance. These features make it a preferred choice for modern cable systems across utility, industrial, building, and infrastructure applications, supporting long service life, reliability, and efficient power delivery.