Investigating the Influence of Different Types of Nanoparticles on Thermal and Dielectric Properties of Insulation in Converter Transformer

Du, B. X.

doi:10.5772/67432

Cited by 3 publications

(2 citation statements)

References 26 publications

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“…But, this theme is not very simple to challenge because the experiments must be carried out for the polymer samples subjected to a high voltage. Different from the case of the application of a low electric field, which causes a slight change of the electron distribution in a molecule or an aggregation of molecules and the dielectric behavior can be deduced as well known, − the experiment under the application of middle or high electric field, which may give us information about the changes in the electric dipole orientation, the chain conformation, the aggregation structure of the chains, and even the higher-order structure composed of the crystalline and amorphous regions, is difficult to perform for the crystalline polymer substances because of an easy occurrence of the dielectric breakdown. , The experimental reports have been quite limited even when we search the literature carefully.…”

Section: Introductionmentioning

confidence: 99%

High-Electric-Field-Induced Hierarchical Structure Change of Poly(vinylidene fluoride) as Studied by the Simultaneous Time-Resolved WAXD/SAXS/FTIR Measurements and Computer Simulations

et al. 2021

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A high electric field was applied cyclically to poly(vinylidene fluoride) films, during which the simultaneous and time-resolved measurements of the two-dimensional wideangle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), and transmission-type Fourier transform infrared (FTIR) spectra were performed using a synchrotron X-ray radiation system. The inversion of the CF 2 dipole moments caused by the alternate change of the electric field vector direction was detected to occur around ±80−100 MV/m as estimated by the electricfield-strength dependence of the IR band intensity. On the other hand, the WAXD peaks were found to show the maximal intensities at 0 and ±250−300 MV/m. In these regions, the 001 reflection of the β form and the 002 reflection of the δ form changed the intensities remarkably and periodically. These experimental data were interpreted, not by the idea of a simple inversion motion of the rigid polar chains (the planar zigzag chains of the form β and the TGTG̅ chains of the α and δ forms) but by the more complicated couplings between the rotation and tilting motions of the chain segments, the cooperative T-G conformational exchanges, and the associated inversion motion of the CF 2 dipoles. The idea of the cooperative chain motions was supported by the density functional theory calculations performed under the external electric field. Different from the remarkable changes of the WAXD and FTIR data, the SAXS patterns did not show the detectable changes in these processes, indicating that the above-mentioned cooperative structural changes should occur in the crystalline regions with the stacked lamellar structure kept unchanged.

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Section: Introductionmentioning

confidence: 99%

High-Electric-Field-Induced Hierarchical Structure Change of Poly(vinylidene fluoride) as Studied by the Simultaneous Time-Resolved WAXD/SAXS/FTIR Measurements and Computer Simulations

et al. 2021

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“…Aggregation structure of polymer chains in the solid state is not only related to the mechanical property but also related intimately to such electric properties as dielectric, piezoelectric, pyroelectric, and/or electric insulation properties. − In order to understand these electric properties from the microscopic point of view, we need to reveal the static and dynamic structures of the chain aggregations under the application of the electric field. The static structure means the structure detected in the stabilized or equilibrated state.…”

Section: Introductionmentioning

confidence: 99%

Electric-Field-Induced Phase Transition and Crystal Structural Change of the Oriented Poly(vinylidene Fluoride) β Form as Clarified by the In Situ Synchrotron Wide-Angle X-ray Diffraction Measurement

et al. 2022

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In situ synchrotron wide-angle X-ray diffraction measurements have been performed successfully for the oriented poly(vinylidene fluoride) β form under the periodically changed high electric field. (i) The β form existing under the low electric field (βlow‑E ) was found to transform to the βhigh‑E phase when subjected to an electric field higher than ca. ± 150 MV/m, as known from the remarkable X-ray diffraction profile change between two phases. In addition, (ii) the inversion of the polar b-axis (or the CF2CH2 dipoles) and (iii) the titling of the zigzag-chain stems were found to occur simultaneously, as already reported in our previous paper (Macromolecules 2021, 54, 2334). These three kinds of phenomena (i–iii) have been found to occur systematically in a cooperative manner. Once the βhigh‑E phase was created in the highest electric field strength, it was reserved in the process of decreasing the electric field strength to 0 MV/m, during which, however, the stepwise rotation of the polar b-axis and the chain tilting from the oriented direction occurred again. Once when the electric field strength reached ca. −100 MV/m after passing through 0 MV/m, in addition to the cooperative phenomena of the stepwise b-axial rotation and c-axial tilting, the partial transition from the βhigh‑E to βlow‑E phases occurred, and then, the βhigh‑E phase was stabilized again at −300 MV/m. In the recovery process from −300 to 0 MV/m, the βhigh‑E phase was reserved but the b-axial rotation and c-axial tilting still occurred as before. The stepwise b-axial rotation and the cooperative c-axial tilting are speculated to occur through the generation and propagation of TG-kink defects along the chain axis (T: trans and G: gauche C–C torsions), as reported in the previous paper. The quantitative analysis of the observed X-ray diffraction data, in combination with the lattice energy optimization calculations, has allowed us to derive the crystal structure of the βhigh‑E phase in addition to the structure of the well-known βlow‑E phase. The zigzag chains are packed in parallel along the b-axis similar to the βlow‑E phase. However, the unit cell is deformed slightly from the original rectangular shape of the βlow‑E phase to the monoclinic type. On the basis of the thus-collected experimental information, the images of the structural changes occurring under the electric field have been derived concretely.

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Dielectric Properties of Silica‐Based Synthetic Ester Nanofluid

Mahidhar¹,

Sarathi²,

Taylor³

et al. 2021

Alternative Liquid Dielectrics for High Voltage Transformer Insulation Systems

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Investigating the Influence of Different Types of Nanoparticles on Thermal and Dielectric Properties of Insulation in Converter Transformer

Cited by 3 publications

References 26 publications

High-Electric-Field-Induced Hierarchical Structure Change of Poly(vinylidene fluoride) as Studied by the Simultaneous Time-Resolved WAXD/SAXS/FTIR Measurements and Computer Simulations

High-Electric-Field-Induced Hierarchical Structure Change of Poly(vinylidene fluoride) as Studied by the Simultaneous Time-Resolved WAXD/SAXS/FTIR Measurements and Computer Simulations

Electric-Field-Induced Phase Transition and Crystal Structural Change of the Oriented Poly(vinylidene Fluoride) β Form as Clarified by the In Situ Synchrotron Wide-Angle X-ray Diffraction Measurement

Dielectric Properties of Silica‐Based Synthetic Ester Nanofluid

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