As part of commissioning of a new renewable energy site in the Midwest, IMCORP's Factory Grade® assessment was performed on the entire site cable collector system. Substandard partial discharge (PD) activity (per ICEA S94-649) was observed at several points within a cable insulation on a number of phases. A section of the suspect cable was extracted for further analysis at the IMCORP lab in Manchester, CT with the client present. The 35kV TRXLPE jacketed concentric neutral cable sample was reassessed in the lab and found to exhibit the same sub-standard PD activity. To identify the issue causing the PD activity, this area of the cable was dissected and a hot oil and a wafer analysis was performed. A conductor shield protrusion was observed (see accompanying pictures below) at the location where the field assessment had originally identified the PD activity. The defect in the insulation most likely occurred during the cable manufacturing process and this led to the sub-standard partial discharge activity on site. Factory Grade® assessment of the cable system during site commissioning likely saved the customer from multiple costly collector system failures.
Cable Manufacturer’s Defect Found at a Renewable Site