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Influence of alternating electric field intensity on the dielectric response of hybrid nanofluid-paper insulation system
*Roman Cimbala
Department of Electric Power Engineering, Technical university of Košice
Peter Havran
Department of Electric Power Engineering, Technical university of Košice
*Samuel Bucko
Department of Electric Power Engineering, Technical university of Košice
Last modified:
2022-04-13
Abstract
The issue of the application of magnetic nanofluids in electric power devices is currently highly topical, as they have certain advantages and disadvantages. This study provides a dielectric relaxation response (DRR) of an oil-paper insulation system at different AC electric field intensities. As a liquid medium, a hybrid nanofluid with different content of magnetic nanoparticles Fe3O4 and fullerene nanoparticles C60 in their combination is investigated using six samples. DRR is analyzed by the method of dielectric spectroscopy in the frequency domain, where the capacitance and loss ratios are described by the complex permittivity in the frequency band and the complex plane of the Cole-Cole diagram. The results revealed the relaxation process of samples containing magnetic nanoparticles at all applied alternating electric field intensities. Increasing the intensity of the field shifts the relaxation maximum to higher frequencies. Paper samples impregnated with hybrid nanofluid show a decrease in the relaxation maximum with increasing concentration of fullerenes with a gradual shift to lower frequencies, thus increasing the relaxation time of the captured polarization mechanism. This causes a reduction in dielectric losses in the mains frequency band at all-electric field intensities, which is a remarkable feature in terms of practical application. Loss permittivity characteristics in the low-frequency band reveal an increase in values with increasing fullerene concentration relative to the base fluid at all-electric field intensities, as confirmed by the Cole-Cole diagram.
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