Investigation on the transformation of time domain spectroscopy data to frequency domain data for impregnated pressboard to reduce measurement time

The accuracy of different transformation methods for time domain dielectric response data to frequency domain and their limits are studied. First an approximated analytic function is considered, second an extended Debye model for the dielectric behavior of impregnated pressboard. The last method is a numerical integral form and Fast Fourier Transform. Hamon approximation relates time domain data at t to frequency domain data at f=0.1/t and gives the results by sole measurement of polarization current. Dielectric diagnosis of high voltage apparatus can be done by using Hamon approximation in minimum duration. All transformation methods show similar results and they are analyzed in order to demonstrate the limits of the methods.