After laying tests of 400 kV XLPE cable systems for Bewag Berlin

The after laying tests carried out on a 400 kV XLPE cable double-system (length 6.3 km) used AC test voltage combined with partial discharges (PD) measurement on joints and sealing ends for the first time. The approx. 30 MVA test power was delivered by the two-stage mobile resonant test system of variable frequency which was specifically designed for this duty. The requirements to be met by the test system as well as the test arrangement and its connection technology are explained. For the PD measurements, directional couplers were integrated into each joint. The data measured on all joints were simultaneously recorded and centrally evaluated. The voltage tests carried out up to 400 kV and the high-sensitive PD measurements done on the joints with a PD detection level of 2 pC confirm that such test and measuring systems allow to achieve informative commissioning and diagnostic tests on extra high-voltage cables also under difficult on-site conditions.