Early detection of degradation is crucial to prevent severe cable damage. This paper explores the possibility of using the cable screen currents as an indicator of cable aging status. A T-circuit model is developed for three single-core coaxial cables excited by three-phase voltages, where the XLPE insulation is modelled using a parallel conductance (G) and capacitance (C) branch representing a non-linear, voltage-dependent admittance. A set of differential equations are defined for the above configuration to describe the harmonic content of the leakage current under partial discharges as a result of insulation deterioration and water treeing.

Paper presented at JICABLE 2023.