Identification of aged cable section in 12.5 kV URD system based on Frequency Spectrum

Underground residential distribution (URD) power cables are aged due to electrical, thermal, mechanical and environmental stress during their service. For utilities, the recent dielectric conditions of the cables are of much interest. Fast Fourier Transform Analysis of the impulse wave propagating in URD is one of the online non-destructive methods to estimate the cable insulation condition. In this study, the radial URD system with aged cable sections was modeled using EMTP for transient studies. A switching transient was simulated in the energized model of the URD system. Based on the Frequency Spectrum of the voltages at different points in the model URD, an aged cable section identification methodology using feature classification is presented in this paper.