Insulation Degradation Assessment of 10 kV XLPE Cable by High-Voltage-Impendence Measurement

Capacitance or impedance changes are key indicators for assessing cable insulation degradation. A test circuit was developed to measure capacitive reactance under high voltage at varying frequencies, considering the much higher resistance of the insulation layer compared to its capacitive impedance. Results show that lower frequencies lead to reduced current and increased phase angle. Aging tests at 135°C revealed a decrease in capacitance and corresponding changes in impedance and phase angle. To ensure accurate phase angle measurement, the protective resistance was adjusted based on capacitance variations. The proposed method demonstrates preliminary feasibility for detecting insulation degradation in 10 kV XLPE cables.