Development of watertree retardant XLPE cables

The development and testing of a WTR XLPE (watertree-retardant cross-linked polyethylene) insulating material in MV (medium voltage) cables are outlined. The main phases of the development are postulation of a hypothesis of WT initiation and growth; investigation and verification of the WTR efficiency of a WTR compound on a laboratory scale, projection of the laboratory results to large-scale manufacture, verification of the ability to produce full-scale cables with the WTR insulating compound on conventional manufacturing lines; and electrical short- and long-time tests on these cables under rigorous aging conditions. It is concluded that the development has resulted in a WTR XLPE cable which compares favorably with standard XLPE cables in most respects, while at the same time showing a vastly improved resistance to watertree formation