A newly installed wind farm began experiencing multiple cable and accessory failures shortly after commissioning. The renewable sites' underground cable system had initially been tested using a very low frequency (VLF) method, but after multiple cable and accessory failures, the owner consulted the cable manufacturer about the problems they were experiencing. The cable manufacturer advised the owner to conduct a thorough PD testing of the cable system to verify the system quality and identify problems.
IMCORP’s Factory Grade® technology found many cable PD sites and multiple improperly installed separable connectors. The issue found with the separable connectors was that the cable adapter (the effective stress control element) was not in contact with the semi-con. This dimensional error significantly reduced the electrical stress grading, resulting in PD activity ending in future system failure (as it did in previous cases that first year). Once this issue was recognized, the wind farm owner made the appropriate repairs and had IMCORP perform the Factory Grade® assessment. By using IMCORP’s Factory Grade® assessment, this wind farm owner was able to upgrade his cable system to meet manufacturers’ specifications.