Abstract
The oil-based nanofluids with greater dielectric strength have attracted much attention as a crucial insulating materials in high-voltage oil-immersed power equipment. In fact, the different microstructures of the transformer oil-based nanofluids (TNFs) would result in different dielectric properties. In this work, the broadband dielectric spectroscopy measurement was used to establish the linkage between the electric double layer (EDL) and dielectric response properties of TNFs which was performed at 298K temperature and with frequency range from 10-2Hz∼106Hz. The modified Havriliak-Negami (HN) model function was used to analyze the measured results. The results demonstrate that both the real and imaginary parts of dielectric spectra of two kinds of oil are composed of the conductivity and polarization process. Compared with pure oil, two polarization process could be observed for the TNFs, explained by the EDL structure reasonably. The introduction of the EDL structure provides an idea to account for the insulating strength improvement of TNFs for the first time.
Highlights
Mineral oil is used widely in power transformer around the world
It is reported that the alternating current (AC) and direct current (DC) breakdown voltage of transformer oil were enhanced by the addition of nanoparticles, but the modification mechanism of transformer oil-based nanofluids (TNFs) is not clear currently,[6,7,8] because we know little about the microstructure of the TNFs, especially the interphase structure between oil and nanoparticles
In order to explore the microstructure and the phenomena of dipole relaxation arising from the reorientational motions of molecular dipoles and the electrical conduction arising from the translational motion of electric charges, the Broadband Dielectric Spectroscopy (BDS) measurement was applied for the TNFs for the first time
Summary
Mineral oil is used widely in power transformer around the world. In order to explore the microstructure and the phenomena of dipole relaxation arising from the reorientational motions of molecular dipoles and the electrical conduction arising from the translational motion of electric charges (ions, electrons), the Broadband Dielectric Spectroscopy (BDS) measurement was applied for the TNFs for the first time. It is sensitive to a variety of relaxations, especially those related to the interfacial polarization induced by charge gathered at the interface.[9,10] The charged surface of nanoparticles and interphase information between oil and nanoparticles can
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