IMCORP Blog

Carbon Black Residue at a Utility Cable Termination

By: IMCORP

 

IEEE 386 Non-Compliant
While performing IMCORP's Factory Grade® assessment for a utility client, IMCORP detected sub-standard partial discharge (PD) activity at a URD cable termination. After the assist crew cleaned and greased the indicated termination, the cable was retested and the same PD was present. The crew removed the elbow, examined the termination, and discovered the cause of the PD activity to be a buildup of conductive black carbon material adhering to the insulation. This defect was most likely caused by a workmanship error while stripping the black semi-con off of the cable insulation in preparation for the termination installation.

Like many of the defects uncovered by IMCORP's Factory Grade® technology, the magnitude of signal from the PD activity at this site was very small, only 19pC.  Less sensitive tests would have been unable to detect the existence of this defect, despite the fact that it would impact the long term performance of the cable system.




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