Effects of nano-sized MgO-filler on electrical phenomena under DC voltage application in LDPE

Murata, Y.; Murakami, Yoshinobu; Nemoto, Masaaki; Sekiguchi, Y.; Inoue, Y.; Kanaoka, Mamoru; Hozumi, Naohiro; Nagao, Masayuki

doi:10.1109/ceidp.2005.1560645

Cited by 39 publications

(30 citation statements)

References 2 publications

(2 reference statements)

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“…The thickness dependence of the thermal breakdown strength was shown, and the thermal breakdown strength for a 0.2 mm thick sample was almost twice as high as for a 20 mm sample. When the calculated results were compared with experimental data from [9] it was found that the experimental data showed higher breakdown strength than the calculated. Any transient effects of the DC ramp that was used in the experiments were not included in the calculations.…”

Section: Introductioncontrasting

confidence: 50%

Numerical investigation of temperature and electric field dynamics in polymer insulation at HVDC

Olsson

2009

2009 IEEE Electrical Insulation Conference

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At sufficiently high DC electric field in polymer insulation breakdown will occur due to heating. The current that passes through the insulation depends on the electric field, the temperature, and the composition. The associated temperature rise depends on the thickness of the insulation layer and the thermal boundary conditions. A numerical model has been used to study the temperature and electric field dynamics at ramp tests of flat insulation layers. The average electric fields at thermal breakdown have been evaluated for different insulation thicknesses and thermal boundary conditions. The thermal breakdown field can be twice as high for a 0.1 mm well cooled insulation sample as compared to a 10 mm thick sample that is naturally cooled, and the thermal breakdown field increases with increasing ramp rate.

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Section: Introductioncontrasting

confidence: 50%

Numerical investigation of temperature and electric field dynamics in polymer insulation at HVDC

Olsson

2009

2009 IEEE Electrical Insulation Conference

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“…If the barrier, which is presumably Coulombic, is increased by nano-fillers through some mechanism, electron injection will be reduced so as to prolong tree incubation period and thereby enhance electric field strength for tree initiation. Some of electric field threshold data of electro-luminescence and space charge support the increase in the barrier height, as electron injection is suppressed due to nanostructuration (3) (11) . During the tree growth period, a tip of tree will be influenced by nano-fillers, because the spacing between neighboring nano-fillers is the same order of their diameter, i.e.…”

Section: Role Of Nano-fillersmentioning

confidence: 94%

Treeing Phenomena in Epoxy/Alumina Nanocomposite and Interpretation by a Multi-core Model

et al. 2006

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ObjectivesIn order to clarify how different treeing lifetime and tree growth behavior were between epoxy resins and their nanocomposites, laboratory-prepared epoxy/boehmite alumina nanocomposites were subjected to local high electric filed using treeing test cells, and were evaluated on their treeing performances. Both results experimentally obtained are interpreted based on a multi-core model, and some contradiction in explanation is pointed out for further research. A crossover phenomenon was newly found and interpreted in terms of the multi-core model. ResultsTreeing phenomena in epoxy/alumina nanocomposite were experimentally investigated and explained to some extent in terms of a multi-core model. Role of nano-fillers was discussed and clarified for treeing resistance. Major results are as follows:(１) Alumina nano-fillers are effective to suppress both tree initiation and propagation. Optimum content of the nano-fillers is around 5 wt% at our current manufacturing technology.(２) It was found that there are two kinds of tree growth processes, i.e. thin channel formation and thick channel formation. At high field, the former is followed by the latter.( ３ ) It was elucidated that thin tree channels reach the opposite electrode at high field, but cause no breakdown in both pure epoxy and its nanocomposite. Treeing breakdown takes place, when thick channels bridge a dielectric specimen, as usually anticipated.(４) Tree channels are broadened from thin to thick by partial discharges (PD's) taking place inside the channels. PD products emerge onto the inner surface in nanocomposites, but no PD products are traced in pure epoxy.(５) A crossover phenomenon as shown in Fig. 1 is recognized in tree growth vs. applied voltage characteristics between pure epoxy and its nanocomposite. Selective paths for thin tree channel formation at high field are assumed in the nanocomposite for explanation.(６) Increase in tree initiation threshold is explained by the increase in the height of a barrier between the electrode and the dielectric. This increase is substantiated by the effect of charge redistribution that is considered to be formed near the metal electrode. This charge redistribution must be caused by the collective role of the electric double layers that each of the multi-cores in the multi-core model may possess.(７) Difference in the speed of thin channel formation at high electric field between pure epoxy and its nanocomposite is interpreted by the concept of rather straightforward selective paths. It is suggested that such paths will be effective with the repulsive force caused by charge tails of the electric double layers that the multi-cores of nano-fillers generate.(８) At medium electric field, nano-fillers or multi-cores are considered to work as high permittivity media to invite a tree tip filled with partially ionized conducting gas. This can explain longer tree growth time in nanocomposites than in pure epoxy.(９) Nanocomposites are more erosion-resistant inside the tree channels than pure epoxy, as clarified in s...

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“…Cross-linked polyethylene (XLPE) insulation with nano fillers is preferred for extra high voltage dc power cables, since it exhibited better dc dielectric performance than simple XLPE insulation [4]. In this regard, various dielectric properties of low density polyethylene (LDPE) with nano fillers such as MgO nano fillers have been intensively investigated as fundamental study [5] [6].…”

Section: Introductionmentioning

confidence: 99%

Tree initiation and growth in LDPE/MgO nanocomposites and roles of nano fillers

Tanaka

Iizuka

Sekiguchi

et al. 2009

2009 IEEE Conference on Electrical Insulation and Dielectric Phenomena

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Processes of tree initiation and growth in LDPE/MgO nanocomposites were investigated by using optical and partial discharge (PD) detection methods. They can be divided into three stages depending on tree length. The first stage corresponds to the initial growth of about 10 m and might be subtly affected by the filler content up to 1 phr. This might be influenced by Coulombic field formed around nano fillers. The second stage is interpreted as tree growth around 100 m, and is suppressed by nano fillers up to 2 phr, where trees grow by colliding with nano fillers. The third stage leads to final breakdown at which tree lengths are of 1 mm order, and are retarded by nano fillers up to 10 phr, where PD erosion processes are involved.

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Effects of nano-sized MgO-filler on electrical phenomena under DC voltage application in LDPE

Cited by 39 publications

References 2 publications

Numerical investigation of temperature and electric field dynamics in polymer insulation at HVDC

Numerical investigation of temperature and electric field dynamics in polymer insulation at HVDC

Treeing Phenomena in Epoxy/Alumina Nanocomposite and Interpretation by a Multi-core Model

Tree initiation and growth in LDPE/MgO nanocomposites and roles of nano fillers

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