Test Cell For Polarization And Depolarization Current Test Of Transformer Insulation Oil

Polarization and Depolarization Current (PDC) analysis is normally used to determine the water content in the oil-paper insulation barrier and also oil conductivity inside the transformers. PDC measurement onsite was performed by injecting the DC Voltage at one side of the transformer and current measurement will be carried at the other side of the transformer, in which the transformers are required to be isolated from services to be tested. PDC test normally run up to 10000s for polarization and had to wait for other 10000s for depolarization measurement. Because of the long duration of the test, applications of this method to monitor transformer on service become less popular. In this research, a cell was designed and developed to perform PDC on insulation oil samples. The PDC pattern of insulation oil obtained by testing using the cell was found to have same pattern with the test done onsite. Predictions for transformers in service can be made by performing PDC tests on oil samples taken from the transformer tank and then comparing its pattern, conductivity level and measured capacitance value against a PDC fingerprint.