ABB Review Special Report - ABB - ABB Group

and the system as a whole will stillwork. This is why limits are given forthe electrical stresses in the constructionrequirements in IEC 60502.HV and EHV cables and accessories, onthe other hand, are designed as systems.No construction requirements exist forcables for these voltage levels, just thetest requirements in IEC 60840 andIEC 62067.400-kV XLPE cable projectsIn 1996 ABB received an order from thepublic utility Bewag (now VattenfallEurope) to supply and install a 400-kVXLPE cable system in a 6.3-km longunderground tunnel in the center ofBerlin. The ventilated tunnel is situated25 to 35 meters below ground and has adiameter of 3 meters 5 . The cable system,with a 1600 mm 2 segmented copperconductor, has a transmission capacity of1100 MVA and forms part of a diagonaltransmission link between the transmissiongrids west and east of the capital.The cable is installed with the threephases arranged vertically, one abovethe other, on specially designed cablesaddle supports7.2 metersapart, with ashort circuitproofspacerin the middleof each span.The cable routewas dividedinto nine sections,eachapproximately 730 meters long. GISterminations were installed at the twosubstations and the new ABB joint wasused to interconnect the cable lengths.The laid cable consists of three maincross-bonded sections, with three minorsections within each main section.The cable circuit went into service inDecember 1998.Greater lengths of lowweightXLPE cable canbe wound onto anygiven drum, while higheddy-current losses inthe sheath are avoided.The Bewag utility subsequently awardeda second 400-kV XLPE cable contractto ABB, this time for a 5.4-kmlong system, again in an undergroundtunnel. This cable circuit completes thediagonal link betweenthe transmissiongrids west andeast of Berlin, andwas handed overto the customer inJuly 2000.Further 345–400 kVcable projectsawarded to ABBinclude orders for 200-km XLPE cables,accessories and installation. Commissioningof these projects is scheduledto take place during 2003–2004.New submarine cable projectsIn 1998 ABB was awarded the ChannelIslands Electricity Grid Project, whichreinforces the power supply fromFrance to Jersey and, for the first time,connects Guernsey to the Europeanmainland grid. The submarine part5400-kV cable system in a 6.3 km underground tunnel running through Berlin’s city center50Special ReportABB Review