Observation and Modeling of Water Tree in 60 kV-class XLPE Cable-Investigation of AC Loss Current and Electric Field Using Transient Electric Field Analytical Model-

Water tree is one of the causes of insulation deterioration of cross-linked polyethylene (XLPE) cables. In 60 kV-class XLPE cables, elongated water trees may be found as a factor that deteriorates their insulation performance, and it is necessary to detect deterioration signals caused by such water trees in deterioration diagnosis to understand deterioration states of the cables. In this study, we used an electric field analysis software to model an elongated water tree and a bowtie tree observed in 60 kV-class removed aged XLPE cables, and examined influence of the length of the water tree and the position of the bow-tie tree on the AC loss current and the maximum electric field by using transient electric field analysis.