Thermal degradation of transformer pressboard impregnated with magnetic nanofluid based on transformer oil

Cimbala, Roman; Bucko, Samuel; Kruzelak, Lukas; Kosterec, Michal

doi:10.1109/epe.2017.7967335

Cited by 7 publications

(5 citation statements)

References 8 publications

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“…These polar substances are also responsible for the occurrence of relaxation mechanisms in the sample with Fe 3 O 4 and C 60 in the low-frequency band during the entire period of thermal aging. The increase in α at the end of the observed thermal aging of 4500 h, compared to the reference values (0 h), is related to the breaking of the C-H bonds of the liquid molecules [50]. This causes the release of polar substances into the liquid volume, increasing the relaxation time τ and the distribution of relaxation times α.…”

Section: Cole-cole Distribution Of Relaxation Timesmentioning

confidence: 87%

Frequency-Dependent Dielectric Spectroscopy of Insulating Nanofluids Based on GTL Oil during Accelerated Thermal Aging

et al. 2022

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Improving the dielectric properties of liquid-insulating materials is a current problem in research into the insulation system of a power transformer. Modern optimization of insulating liquids involves the potential use of unique synthetic esters enriched with nanoparticles. This study presents the results of the dielectric response of liquefied gas-based (GTL) insulating liquids during accelerated thermal aging. The dielectric relaxation spectroscopy method was used in the frequency domain to point out power losses as an imaginary part of a complex electric modulus. The relaxation spectra express the validity of applying this complex dielectric parameter. The polarization processes of the base oil alternately change position in the low-frequency band during thermal aging. Fullerene nanofluid undergoes three phases of dielectric loss changes during thermal aging. In the case of magnetic nanofluid, the effect of electric double-layer polarization disappeared after 500 h of thermal aging. It was found that with the gradual increase in the thermal aging time, there is no gradual increase in the dielectric losses investigated in the measured frequency spectrum. This study shows that the concentration of the two types of nanoparticles independently causes a different dielectric response to an applied AC electric field in the GTL base fluid.

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Section: Cole-cole Distribution Of Relaxation Timesmentioning

confidence: 87%

Frequency-Dependent Dielectric Spectroscopy of Insulating Nanofluids Based on GTL Oil during Accelerated Thermal Aging

et al. 2022

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“…Roman et al . investigated magnetic nanoparticles effect on the thermal degradation of oil–paper insulation [111] and found that magnetic nanofluids impregnated pressboard offer much more resistance to moisture than that pressboard impregnated by pure mineral oil. In addition, nanofluids maintain stable within 800 h of thermal aging at 90°C.…”

Section: Colloid Interaction With Cellulosementioning

confidence: 99%

Electrical and thermal properties of insulating oil‐based nanofluids: a comprehensive overview

Huang

Yao

et al. 2019

IET Nanodielectrics

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Nanofluids, formed by adding nanoscale particles to insulating oil, are stable and homogeneous suspensions that present advanced performance of electrical insulation and heat dissipation. This study shows a comprehensive literature review based on the related results of nano-modified insulating oils (both mineral and vegetable insulating oils) to analyse the preparation methods, stability, dielectric spectroscopy, thermal conductivity, breakdown characteristics under AC and DC voltage, the thermal aging performance of nanofluids and oil-paper interaction. Then theoretical models have been introduced to explain the electrical mechanism of nanofluids. In addition, future research is proposed for nanofluids which would be low cost, highly stable and practically applicable to the power transformers.

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“…Cimbala et al [22] studied the dielectric response of NF-paper system insulation after a long aging process; they compared the results with those obtained with base oil and observed better behavior for the NF-based system when moisture from the environment or from the paper-liquid interface passes to the liquid insulation. They also observed the end of NF stability during the aging process, which led to the aggregation of the NPs.…”

Section: Introductionmentioning

confidence: 99%

Influence of Nanoparticles on the Degradation Processes of Ester-Based Transformer Insulation Systems

2022

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The use of nanofluids as dielectric liquids for transformer insulation has been widely investigated during the last decade. A number of authors have performed extensive studies on liquids produced from different types of nanoparticles and base fluids, providing evidence of their good dielectric properties. Nevertheless, nanodielectric fluids are still at the research stage, and they are far from being a solution that can be applied to real transformers. One of the aspects that might be clarified is their compatibility with the rest of the materials present in the transformer and their behavior throughout the life of the equipment. This paper studies the aging process of cellulose impregnated with an ester-based nanofluid and compares it with the process that takes place when the impregnation liquid is a natural ester. Accelerated aging experiments were performed, and physical and chemical characterization of the process with several analytical techniques was carried out. The mechanical degradation of the cellulose was studied in terms of tensile strength, and the evolution of moisture in the paper and oil was monitored throughout the aging process. The study was completed with FTIR and XPS tests aimed at studying the chemical changes of the materials during the aging process. The experimental results suggest that the degradation rate of the cellulose is not significantly affected by the presence of nanoparticles. However, the XPS study revealed that the chemical reactions involved in the degradation processes of both types of insulation might differ. Several mechanisms are proposed in this work.

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Thermal degradation of transformer pressboard impregnated with magnetic nanofluid based on transformer oil

Cited by 7 publications

References 8 publications

Frequency-Dependent Dielectric Spectroscopy of Insulating Nanofluids Based on GTL Oil during Accelerated Thermal Aging

Frequency-Dependent Dielectric Spectroscopy of Insulating Nanofluids Based on GTL Oil during Accelerated Thermal Aging

Electrical and thermal properties of insulating oil‐based nanofluids: a comprehensive overview

Influence of Nanoparticles on the Degradation Processes of Ester-Based Transformer Insulation Systems

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