Service experience for XLPE cables installed in Norway - from graphite painted insulation screens to axially and radially water tight cable constructions

XLPE power cables were introduced in Norway by Alcatel Kabel Norge AS in 1968. The standard XLPE construction sold to the Norwegian electric utilities today is an axially and radially watertight power cable construction presented in 1991. The objective of this paper is to summarize test results that show the development steps of the Norwegian XLPE power cable and combine this with the actual service performance presented in the Norwegian XLPE power cable failure statistics. The report shows that the long term wet ageing performance of power cables produced today is significantly improved compared to cables produced in the 1970s and 80s. Still, however, water trees do initiate in the new power cables if they are subjected to long term ageing tests. Therefore in order to ensure an entirely watertight cable, an aluminium foil under the PE-sheath is presented as the standard XLPE power cable in Norway today. More than 80% of the MV power cable market are using this cable construction in their power networks.