In the estimation of moisture content of the inverted-type oil-immersed current transformer (IOCT) insulation system, the interfacial polarization between oil-immersed insulation paper and semi-conductive paper should be considered. The classical… Click to show full abstract
In the estimation of moisture content of the inverted-type oil-immersed current transformer (IOCT) insulation system, the interfacial polarization between oil-immersed insulation paper and semi-conductive paper should be considered. The classical model functions of frequency-domain dielectric spectroscopy (FDS) are no longer applicable. Therefore, the planar layered two-phase system model is applied in this paper. First, the FDS of oil-immersed paper and semi-conductive paper with certain moisture content is measured using Alpha-A broadband dielectric spectrometer. Then, the FDS of oil-immersed insulation paper is explained using the Havriliak–Negami (H–N) model function and the amendatory H–N model function considering that the dc conductance is used to explain the FDS of semi-conductive paper. The two functions are substituted into the planar layered two-phase system model. The model parameters are fit by means of least-squares technique. Finally, the numerical relationship between the chosen characteristic parameter and the moisture content of the IOCT insulation system is obtained by least-squares technique. In engineering, one can use the results considering the influence of interfacial polarization to estimate the moisture content of the IOCT insulation system.
               
Click one of the above tabs to view related content.