Internally Oil-Cooled Oil-Filled Cable (Separated Type)

The internally oil-colled cable was studied for the main long-distance large power underground cable. The cooling oil of the cable is separated from the insulation oil. An unique and very compact feeding joint was developed, at which the cooling oil was extracted from or fed to the high voltage cable. The electrical and mechanical initial tests of the cable and accessories were successfuly carried out making a loop 40m long for 275 kV class.