Design of HV switching for polarization & depolarization current measurement

The method of assessing the insulation condition in high voltage (HV) electrical equipments can never be overemphasized. Over the years, several method of assessing the insulation condition have been researched & used by many researchers. One of these methods is using the dielectric response of the materials to determine the Polarization and Depolarization Current (PDC). PDC is a non-destructive assessment method that combines a sequence of switching operations & current measurement for time domain response. In this paper, the HV switching sequence for a PDC assessment was designed & built to fulfill the PDC assessment basic theory. The switch was applied on three materials used in HV insulation to determine their polarization current (ip) & depolarization current (id). Test duration for both ip & id were 10000 seconds and the test results are presented as a current pattern. The current pattern is consistent with the theoretical current wave PDC pattern from literatures thereby confirming the validity of the built switching device.