Performance of Extruded Dielectric (XLPE) Cable

Samples from a 138kV XLPE cable tested at Waltz Mill are examined and compared with an unenergized piece. Several new analytical techniques are employed and studies are made concerning the distribution of discontinuities (contaminants, ambers, voids, and trees, etc.), cure-related items (extractables, density, residual peroxide and decomposition products, etc.), thermal and oxidation stability, incipient voids and trees, and shield-to-insulation smoothness. Changes are seen for many of these factors between the original and tested cable samples. Some of the effects are subtle, complex and/or unsuspected. The overall assessment for XLPE power cables, however, is encouraging.