XLPE (Cross-Linked Polyethylene) is a thermoset insulation material. Cross-linking is a process that modifies the molecular structure of polymer chains, creating stronger bonds between them. This cross-linking can be achieved through either chemical or physical methods.Chemical cross-linking involves adding chemicals or initiators, such as silane or peroxide, to generate free radicals that create cross-links between polymer chains. Physical cross-linking involves exposing the polymer to high-energy sources, such as electron beam or microwave radiation.
Polyethylene (PE) itself offers excellent dielectric strength, high insulation resistance, and low dielectric loss across a wide range of frequencies, making it an ideal insulating material. However, its operating temperature range is limited. Cross-linking PE into XLPE significantly increases its thermal performance while maintaining its excellent electrical properties.
XLPE vs. PVC Cable Insulation
XLPE is suitable for voltage ranges from low voltage (LV) to high voltage (HV), outperforming other insulation materials such as PVC (Polyvinyl Chloride), Ethylene Propylene Rubber (EPR), and silicone rubber in many applications.Cross-linking polyethylene improves its resistance to heat, chemicals, and oils, making it suitable for use with Low Smoke Zero Halogen (LSZH) cable constructions.
The mechanical properties of XLPE are superior to many other insulation materials, offering higher tensile strength, greater elongation, and improved impact resistance. The addition of carbon black can further enhance resistance to hot deformation and cutting. XLPE insulation will not melt or drip, even at soldering iron temperatures, and provides improved current-carrying capacity along with excellent long-term aging performance.
Another significant advantage of XLPE insulation over conventional PE insulation for low-voltage (LV) and medium-voltage (MV) cables is its excellent resistance to water treeing. Water treeing is a type of insulation degradation in which microscopic cracks develop and grow in the direction of the electric field under electrical stress. It is important to note that this phenomenon is not limited to PE materials alone.
