Stephen Cree

A next generation advanced water tree-retardant crosslinked polyethylene insulation for long life power cables

Underground cables used in wet environments that are insulated with crosslinked polyethylene (XLPE) have experienced premature failures due to a phenomena known as water treeing being associated with the failures. Developments in polyethylene insulation technology minimized this water-treeing induced problem through the use of water tree retardant crosslinked polyethylene (TR-XLPE). Since the introduction of TR-XLPE in 1983, evolutionary and sometimes revolutionary improvements have been made by both the compound producer and cable manufacturer leading to enhanced cable performance and greater value to the power industry A next generation, advanced TR-XLPE insulation that represents a major step change improvement in wet electrical performance has been developed. The next generation, advanced TR-XLPE insulation has improved wet electrical performance as demonstrated in laboratory studies and highly accelerated wet cable aging studies with distribution class cables. Additionally, this advanced TR-XLPE insulation shows the potential for use in high voltage cables. Cables insulated with the next generation, advanced TR-XLPE material are expected to further improve the reliability of distribution cable systems and potentially transmission cable systems while also providing cable design engineers the capability to optimize cable designs.

Ethylene alkene elastomers for cable insulation applications

Filled insulation compounds have predominantly been based on ethylene propylene rubber. Ethylene propylene rubber is commonly accepted to encompass ethylene propylene copolymers and ethylene propylene diene terpolymers. Advances in polymer catalyst technology have enabled a broader diversity of ethylene based polymers suitable for cable applications. The ICEA specification for medium voltage cables also allows for filled insulation compounds based on ethylene alkene copolymers. Ethylene alkene copolymers contain the traditional ethylene backbone though they can have a longer alkyl side chain or branch. This class of ethylene alkene elastomers can have the same physical properties, flexibility and electrical performance as ethylene propylene rubber based insulations.