Life-cycle-cost comparison of different degradation diagnosis methods for cables

Degradation diagnosis is aimed at preventing unexpected failure and extending the estimated service life of electric power apparatus. But it is necessary to investigate the economic feasibility of degradation diagnosis, because the life-cycle cost of cable maintenance changes with the diagnostic parameters such as diagnosis cost, diagnosis interval and replacement criterion. Based on the actual data of water-tree degradation, we discussed the economic feasibility of practical nondestructive diagnosis of 6.6 kV XLPE cable, i.e. DC leakage current measurement and residual charge measurement. As a result, residual charge measurement is economically feasible and has higher accuracy than the DC leakage current measurement.