Positive and negative effects of dielectric breakdown in transformer oil based magnetic fluids

Title
Positive and negative effects of dielectric breakdown in transformer oil based magnetic fluids
Authors
이종철이원호이세희이상엽
Keywords
Magnetic materials; Dielectric properties
Issue Date
2012-10
Publisher
Materials research bulletin
Citation
VOL 47, NO 10, 2984-2987
Abstract
The transformer oil based magnetic fluids can be considered as the next-generation insulation fluids because they offer exciting new possibilities to enhance dielectric breakdown voltage as well as heat transfer performance compared to pure transformer oils. In this study, we have investigated the dielectric breakdown strength of the fluids with the various volume concentrations of nanoparticles in accordance with IEC 156 standard and have tried to find the reason for changing the dielectric breakdown voltage of the fluids from the magnetic field analysis. It was found that the dielectric breakdown voltage of pure transformer oil is around 12kV with the gap distance of 1.5mm. In the case of our transformer oil-based magnetic fluids with 0.08%<Φ<0.6% (Φ means the volume concentration of magnetic nanoparticles), the dielectric breakdown voltage shows above 40kV, which is 3.3 times higher positively than that of pure transformer oil. Negatively in the case when the volume concentration of magnetic nanoparticles is above 0.65%, the dielectric breakdown voltage decreases reversely. From the magnetic field analysis, the reason might be considered as two situations: the positive is for the conductive nanoparticles dispersed well near the electrodes, which play an important role in converting fast electrons to slow negatively charged particles, and the negative is for the agglomeration of the particles near the electrodes, which leads to the breakdown initiation.
URI
https://pubs.kist.re.kr/handle/201004/43203
ISSN
00255408
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KIST Publication > Article
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