Abstract
The offshore wind industry and other renewable energy sectors are experiencing a growing demand for cost-effective and reliable static and dynamic high voltage power cables. While wet cable designs—those permitting water vapor ingress into the crosslinked polyethylene (XLPE) insulation—are well established up to 66 kV (Um = 72.5 kV), there is increasing interest in dynamic wet cable solutions for 132 kV (Um = 145 kV) applications, particularly for the electrification of oil and gas facilities and future floating wind projects. This paper presents the results from the qualification of 132 kV wet design power cables.
Test cables rated at Um = 52 kV were produced using a commercial high voltage subsea VCV manufacturing line, and six factory joints were included in the test program. Two different
XLPE insulation materials were subjected to wet ageing for 3000 hours at an electrical gradient of 12.2 kV/mm, following Cigré TB722 test regime B. Additionally, cables and factory joints underwent two years of wet ageing at the same electrical gradient according to test regime A. The applied ageing stress is sufficient to qualify all cable cross-sections for 132 kV operation.
After ageing, all cables and factory joints were evaluated using AC breakdown voltage testing to determine the residual breakdown strength. Water tree analysis was also performed near the electrical breakdown sites. The results demonstrate that the high voltage XLPE cables and factory joints successfully met the qualification criteria for 132 kV wet design under both Cigré TB722 test protocols A and B. Notably, no breakdowns were observed in the vulcanized tape section of the factory joints, indicating a high residual breakdown strength in
this component after long term wet ageing.
These findings confirm the suitability of wet design XLPE cables and factory joints for high voltage offshore and renewable applications, supporting their deployment in future dynamic
and static cable installations.