Necessity of cable diagnosis from the viewpoint of electric power companies

At present, electric power companies in Japan are racing a big wave of liberalization in the area of electric power business. The price competition is becoming more severe, and the power utilities are forced to make efforts towards cost-down. Therefore, it is necessary to use the existing apparatus until their life-limit. In the case of XLPE cables, they have been in use for long time now and some of them are approaching 30 years of their designed lifetime. So, the diagnosis method with high reliability and low cost is needed urgently. Here, the diagnosis method desired by electric power companies is described from the viewpoints of reliability and cost. Also the current status of deterioration of XLPE cables and the diagnosis method on each voltage class are introduced.