Transformation of time domain spectroscopy data to frequency domain data for impregnated pressboard [power system insulation]

If the insulation system is considered as a linear system, transformation of data from one domain to another domain is possible. In this paper, the transformation of data from time to frequency domain for impregnated pressboard is presented. Both frequency and time domain measurements are carried out on impregnated pressboard. The accuracy of different transformation methods and their limits are studied. Several methods for transformation of polarization depolarization current data are investigated in detail. The first method is considered as an approximated analytic function using the general relaxation response. The second method is based on an extended Debye model for the impregnated pressboard to obtain frequency domain spectroscopy data. The last method is a numerical integral form of transformation. All methods show similar results. However, non-linearity exists in the insulation system caused small errors in some case, which have to be analyzed in order to demonstrate the limits of the used methods.