Reduced insulation thickness for extruded medium-voltage power cable systems-cable performance and first network applications

Since the introduction of medium-voltage cables with extruded insulation, essential improvements in materials, design and technology have taken place resulting in a remarkable increase of the electrical and ageing performance. In spite of this technological progress, the specified insulation thickness has never been modified. The currently high safety margins and the increasing cost pressure lead to a study of whether a reduction of the insulation thickness would be possible today. This report presents the results of an investigation on cables with a 4 mm thickness of XLPE or EPR insulation in different designs (France, Germany, Italy, Switzerland) which were tested as 12/20 (24) kV cables. The use of such cables will require adapted accessories. Therefore system tests with slip-on and coldshrink joints and terminations were additionally performed. Finally a proposal for new dimensions of extruded medium-voltage cables is made and the first realisations in utility networks in Belgium and France are presented.