Development of Y-branch type prefabricated joint for 275 kV XLPE and fluid-filled cable

When a new substation is planned to be introduced in the urban area, π branched lines are generally employed from the nearest existing transmission lines. In order to minimize the material and installation cost of the switching equipment, its housing and cables, it was determined to develop Y-branch joint (hereafter called by YJB) for 275 kV class by a joint study between a utility company and cable manufacturers. It was so designed suitable to connect not only the existing 275 kV XLPE cable but also the existing 275 kV fluid-filled cable even in the limited space in tunnel without any modification of the tunnel. XLPE cable side, pre-fabricated type joint technology was applied, putting the stress of simple assembly procedure. It was confirmed that the YJB is suitable for the actual application both from its performance and its easiness of installation. The utility company has a plan to adopt this newly developed 275 kV YJB in the near future.