How to maintain continuous power supply while measuring for weak spots.
Peter van der Wielen is a consultant and Barry Ward is a senior consultant at KEMA. Contact van der Wielen at peter.vanderWielen@kema.com.
Failures in medium-voltage power cables and their components cause a large proportion of annual power service interruptions, especially in high-density urban areas. Locating and repairing weak areas in cables at an early stage can improve the reliability of the energy supply considerably.
Analytical methods for asset management that depend on cable-specific failure models work best when the condition of the cable is known. Partial discharge testing is a proven condition assessment/test methodology. A partial discharge (PD) is a short pulse that originates from weak spots along a cable.
In its current form, PD testing occurs offline and involves some drawbacks in terms of cost, risk of damage to the cable, safety, and operational impact. However, a new measuring technique has been developed that can diagnose and locate PD activity on a medium-voltage power cable while the cable remains in service. The patented system, which was created by KEMA in partnership with the Eindhoven University of Technology in the Netherlands, uses inductive sensors to detect, diagnose, and locate partial discharge activity along a medium-voltage power cable while the cable remains online.