Dielectric Response Analysis on Artificial ZnO Surge Arrester Degradation Using Polarization and Depolarization Current Based Method

This paper presents an alternative method to investigate the problems of surge arrester based on dielectric response analysis. The study is made using a 21-kV, 25-kA station class surge arrester to be test specimens, the former Zinc Oxide (ZnO) varistors inside were removed and replaced with artificial degraded ZnO varistors (impulse ageing, tracking problems, moisture ageing under wet and dry condition and cracking ZnO varistors). The experiments are carried out by Polarization and Depolarization Current (PDC) measurement. The test result analyses were proposed in terms of both the time domain and frequency domain. The measurement results show significant differences in dielectric response characteristics between healthy surge arresters and aged surge arresters. In addition, the dielectric response analysis tends to characterise the problems of surge arrester i.e., conduction problems and polarization problems which will be further discussed in this paper.