Study on insulation diagnosis for XLPE cables using dumping oscillating high voltage

6 kV to 60 kV class XLPE cables are widely used and have been playing important roles in power distribution and transmission systems in Japan. For the XLPE cables in these voltage levels, the water tree dominates aging degradation. Therefore, precise on-site detection techniques of water trees in their length are considered to be important for operation and maintenance of these XLPE cables. The author has been investigating the applicability of the dumping oscillating high voltage (DOHV) to the water tree detection as well as insulation diagnosis for these XLPE cables. This paper firstly investigates on the partial discharge measurement under DOHV application for water tree deteriorated 6.6 kV XLPE cable. Then, authors discuss the applicability of OHWV to the insulation diagnosis of XLPE cables combined with partial discharge measurement under DOHV application.