KEMA has developed a method to continuously monitor the condition of medium voltage cables while they remain in service. The patented system, which was created in partnership with the Netherlands’ power grid operators and 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 on-line. Field deployment of the first PD Detection On-line with Localization (PD-OL) units occurs this summer. 

After demonstrating the PD-Online monitoring system’s functionality a year ago, KEMA is now working with a manufacturer to take it into production. The first prototype units are set to roll off the production line in July, to be followed by a series of units to be used for field trials. Each of the Netherlands’ three main grid operators will install units within their networks. French energy company EdF also has ordered a number of PD units with a view to starting online monitoring of its cable circuits.

Storing and analyzing
KEMA is now developing a PD-OL control center at its Arnhem headquarters.  The control center will use the Internet to receive tabulated data from the monitoring and incoming data will be stored, analyzed and interpreted. The computation findings are measured against knowledge rules defined by KEMA based on fifteen years of offline testing. Analytical data and knowledge rules are combined to determine the level of risk posed by any partial discharge activity detected and the possible cause. KEMA also offers clients the opportunity to directly monitor their cable circuits.

Reduction in outages
Once the monitoring units and the data room are fully operational, the grid operators will immediately realize the benefits of the PD-OL system. It is anticipated that deployment of this system will lead to a significant reduction in the overall duration of outages and may enable grid operators to defer capital expenditure.