Ageing of Medium Voltage Cables

Cables are important components in the transportation and distribution of electricity. Due to the increased need for power, but also because overhead power lines are often replaced by (underground) power cables in densely populated areas, the importance of power cables has grown over the years.

Successful asset management, in particular determining the residual lifetime of installed cables, relies heavily on the use of information coming from a variety of sources including the operating managers, the manufacturers, the maintenance managers, the repairers and the technical experts (who perform on-site electrical measurements and material analyses). This often results in a very complex decision making process, based on vast amounts of information that must be considered in the context of a technical, economic and societal framework.

For the technical evaluation of the condition of a cable, a lot of expertise is needed. Knowing the failure mechanisms and ageing processes is mandatory in order to choose the right testing procedures. Also the interpretation of the measurements and laboratory analysis is difficult, especially for complex degradation mechanisms such as the growth of water trees in polyethylene, which remains a subject for debate.