XLPE insulated MV cables; service experience, actual problems and prospects for the future

For some ten years now a single phase cable of simple structure has been used in the Belgian medium voltage power network. The cable consists of an aluminium conductor, an internal extruded semiconductor, XLPE insulation, an external extruded easy strip semiconductor, a copper wire metal screen, and red-coloured outer jacket in reinforced PVC. This type of cable has until now given complete satisfaction. The first cable fault in a three-phase network of more than 1500 km in service since 1979 mainly in a 15 kV network, has not yet occurred. The experiences being good, but inspired by several publications abroad, Belgian utilities decided to carry out a series of life tests of the same kind as those that some years earlier had been carried out on paper-insulated cables. The authors describe these tests which revealed that the intrinsic behaviour of the insulation itself was good, but there is a risk of corrosion on the copper screening