Cables

Partial Discharge (PD) diagnostics on medium voltage cables

Medium-voltage cables sometimes fail, giving rise to outages. Recently, a patented technique has been developed to pinpoint weak spots in the cable connection before actual failure (PD-OL). The technique is based on on-line PD detection and location. This system can be installed and operated on life circuits, and is being installed in a number of circuits. Presently two studies are performed:

  • PD signals are high-frequency signals which propagate over the cables to the detection units. They attenuate during propagation and when they pass (small) substations. The aim of the first project is to determine an optimal strategy for installing the detection units. Further, in this project detection accuracy is increased by proper modelling and signal processing techniques. (link to ISEI-poster Paul)
  • The second project aims to find a relationship between the detected PD activity and the condition of the cable. Although it is clear that PD’s arise from defects, the relation between their statistical distributions and the development of the defect is far from obvious. With the data obtained from systems already installed in the field, this relation is being investigated. Useful application of PD-OL requires reliable interpretation. (link to CMD-poster Shima