The Comparison Between Dielectric Frequency Response and Polarization and Depolarization Current Techniques for Investigating the Defected

This research shows the comparative study of Dielectric Frequency Response (DFR) andPolarization/Depolarization Current (PDC) techniques for detecting the degraded ZnO surge arresters. Four artificial defects (Excessive number of lightning current stress, cracking, moisture ingress, surface tracking) were simulated in 21-kV arresters. DFR analyzed dielectric parameters (capacitance, tan δ) across 1 mHz-1 kHz. Whereas the PDC experiment measured time-domain currents, which could be transformed to frequency-domain characteristics alongside time-domain analysis (DC resistance). Both methods effectively detected the degradation of the problem arrester. DFR provided broad spectral signatures, while PDC offered detailed low-frequency (< 0.1 Hz) insights linked to interfacial polarization. Moisture ingress consistently showed the most severe impact, causing significant deviations in dielectric properties, as observed by both techniques. Other defects also yielded distinct responses. Frequency domain results from DFR and PDC showed a good correlation. The study confirms DFR and PDC as sensitive, complementary diagnostic tools. DFR gives a wide-frequency overview, while PDC excels at low-frequency and polarization analysis. Their use, potentially combined with conventional methods, enhances arrester condition assessment and supports predictive maintenance.