Insulation Diagnosis of Distribution Class Metal Oxide Surge Arrester Using Polarization and Depolarization Techniques

Imperfection of metal oxide surge arrester (MOSA) becomes a factor that affects the power supply quality on medium and high voltage networks. Understanding the coordination of MOSA insulation systems helps describe their failure. This paper presents the analysis of the dielectric response of imperfect MOSA from the factory using polarization and depolarization techniques. The experiments were taken on 21 kV and 24 kV MOSA samples which were validated by testing topics, i.e., the reference voltage, voltage-current characteristic curves, and partial discharge (PD). Polarization and Depolarization Current (PDC) was measured after 21 kV MOSA samples had taken PD testing and 24 kV MOSA samples had taken reference voltage testing. Resistivity, capacitance, and polarization index were interpreted for insulation diagnosis. The importance of non-destructive electrical diagnostics based on polarization methods is validated by PDC test results and is highlighted in detail in this paper. Finally, the results of different PDC were compared and discussed.