Transformer faults classification based on polarization and depolarization current (PDC) measurement test data on mineral oil samples

Abstract

Transformer is the main element of a power system. The insulation of transformer has to be maintained and do regular routine service in order to deliver power effectively. Recently dielectric measurement has been used for assessing the condition of oil/paper insulation. There are several nondestructive dielectric testing method for determining the conductivity and moisture content of insulation materials in a transformer. This research utilizes one of the dielectric methods which are Polarization and Depolarization Current (PDC) analysis in order to identify insulation condition of mineral oil. This paper presents the classifications of breakdown, overheating and partial discharge faults in mineral-oil insulated transformer by using PDC measurement data analysis. The classification is based on the data pattern and statistical analysis. The samples data was obtained from laboratory and from site testing. An analysis result shows that different type of faults will give different outcome to the PDC pattern and as well as statistical data. Based on the result, these three types of faults can be used to identify the insulation condition by using PDC measurement data analysis.