Evaluation Means of Oil-paper Insulation’s Water Based on DC Conductivity

Abstract.The measured spectral line based on frequency domain dielectric spectrum contains multiple superpositions of conductance and polarization processes. In view of the lack of methods to separate the polarization and the conductance processes and the lack of unique methods to characterize the model conductance parameters, the micro conductance processes are studied in depth according to the real and imaginary Kramers-Kronig relation. Firstly, different water content insulation samples were prepared during the laboratory conditions, and dielectric lines in frequency domain were obtained by measurement. Secondly, according to the k-K relation, the relaxation loss spectrum line is obtained by numerical integration of the measured real part of the complex polarization spectrum line, and then the conductivity loss spectrum line is obtained. Finally, the least square method is used to fit the conductivity spectrum line and calculate the conductivity value. The experimental results show that the conductance of the virtual part of the repolarization measurement can be separated from the relaxation loss line by k-K transformation, and the dc conductance can be calculated. At the same time,with the oil-paper insulating sample’s water content increasing, its electrical conductivity is gradually enhanced.