Installation of molded joint by curable PE block insulation for 275kV XLPE cables in the Kitayono line

摘要

In demand of increasing electric power, large capacity transmission lines with 275kV XLPE insulated cable has been installed since 1989 in Japan. Extruded and molded joint (EMJ) are now used for the extra-high-voltage XLPE insulated cable which have excellent electrical performance, high long-term reliability and simpler and more compact construction than conventional types. However, EMJ requires numerous machine operation, specialized and skilled workmanship and consumes assembly time. We have developed a new type of joint, called the Block Molded Joint (BMJ), which combines the advantages of EMI, but shortens the time taken for jointing and simplifies the jointing quality items. The BMJ is formed with curable polyethylene insulation pre-molded block (CPEI, BLOCK) is made of the same material as the cable insulation in the factory, the cables are then inserted into the BLOCK and crosslinked together on site. This paper reports on the BMJ and its simplified quality control and skills of jointing work. It has shortened assembly time compared with the EMJ. We also report on its first application to 275 kV long distance transmission line (Kitayono Line of The Tokyo Electoric Power Co. Inc.).