Crosscomparison of XLPE insulating structure made by different industrial methods of cable cure

Insulating structures made of XLPE (cross-linked polyethylene) by three different industrial methods of crosslinking high-voltage cables-by catenary line, dry cure with nitrogen; by catenary line, wet cure with steam; and by long land die curing process (MDCV-process)-were compared. Structural discontinuities were characterized by frequency, distribution pattern, size, and shape. Of particular interest were spherical inclusions (bubbles), which may be filled with either gas or water. In generically similar XLPE insulating materials for high-voltage cables with large insulation thickness, the different techniques for crosslinking result in significant structural differences. There is a drastic distinction between wet and dry cure regarding void frequency and size. The differences between the two dry cure methods investigated are marginal. The worrisome feature is the clustering of voids. The observed differences favor dry cure methods by a large margin