A comparative study of conductivity and moisture for condition assessment of oil-paper insulation of a transformer

Dielectric response diagnostic method gives us information about the condition of insulation of a transformer. Paper when ages and degrades with time it releases water as byproduct. This water gets mixed with the oil and reduces its dielectric strength. Conductivity values of oil and paper can also be calculated from the dielectric response and which in turn can reflect the condition of oil and paper. Hence it serves as an important parameter to provide information about the condition of oil and paper insulation separately. A test sample has been prepared and conditioned at varying operating voltages, moisture content levels and temperature, to record the polarization and depolarization current. Conductivity values are calculated from the PDC measured data and reported in this article. An estimation of moisture in oil and paper at different conditions have also been calculated, measured and compared for further analysis of the condition assessment of oil paper insulation of a transformer.