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Graphene oxide, a kind of nano-fillers with desirable thermal and electrical properties, could be added to epoxy resin and achieve satisfactory dispersion status due to its hydrophilicity, which lend great help to the preparation of samples. Graphene oxide could be mixed with water since its functional groups, O-H is in harmony with water's functional groups. Furthermore, epoxy resin, flexibilizer,...
Carbon nanotube (CNT) was modified with TDI molecules in order to improve the dispersion of carbon nanotube fillers in organic phase. Semi-conductive layer prepared by epoxy matrix with 0.045 phr CNT was second-time bonded to the neat epoxy for preparing double-layer composite. Broadband dielectric spectroscopy was performed to measure the complex permittivity of neat epoxy, epoxy — CNT/epoxy double-layer...
Generally, UHV converter transformer bushing cores use epoxy resin and insulating paper composite materials as the main insulating dielectric. It is necessary to study the space charge behavior of epoxy resin/insulating paper composites at high temperature and field strength. According to the insulation structure of dry-type bushing core, two epoxy/paper/epoxy three layers Composite samples with different...
In order to study the effect of the glass transition temperature (Tg) on space charge behavior of epoxy resin under polarity reversal voltage, the epoxy resin samples with low Tg were casted in vacuum condition. The dielectric spectra of the samples were measured over the frequency range of 10−1 to 106 Hz at different temperatures. At different temperatures the negative poling field of −30 kV/mm was...
There are more and more converter transformers, bushings, smoothing reactors use epoxy resin or epoxy/insulating paper composite materials as the main insulating medium, in the UHVDC transmission projects. In practice, there are many interfaces between epoxy and insulating paper exist in paper/paper insulation system. Compared with epoxy resin, there are a lot of traps in paper. The structure of the...
Epoxy resin has been widely used in dry-type insulation application such as DC dry-type bushings. In practice, DC dry-type bushings work not only under DC voltage, but also under multiple harmonics with 50Hz fundamental frequency. This study focuses on the effects of space charge behavior of epoxy resin on real voltage of DC dry-type bushings. By using Fourier decomposition, the real voltage of DC...
The mechanical and dielectric properties change significantly when the temperature is close to the glass transition temperature (Tg) for epoxy resin, which is a dry-type insulation materials used in the high voltage direct current (HVDC) power transmission system. In order to study the effect of dynamic glass transition on space charge behavior in epoxy resin, samples with Tg as approximately 82 °C...
The effect of electrode material on the space charge behavior in epoxy resin has been investigated using the pulsed electro-acoustic (PEA) technique. Common metallic electrode materials, i.e. gold, silver and copper, were selected and sputter-coated on the specimens, and the space charge dynamics after the application of various electric fields were monitored at 293 K and 313 K. The space charge accumulation...
Epoxy resin has been widely used in dry-type insulation application, such as dry-type bushings. This study focuses on the temperature effect on the space charge characteristics and dielectric properties of epoxy resin. The space charge distribution measurement has been performed at different electric fields and temperatures by the PEA method, ranging from 2kV/mm to 60kV/mm at 291K, 313K and 343K respectively...
In order to study the interfacial effect on space charge distribution in HVDC bushings which impregnated with epoxy resin, samples just like epoxy-impregnated paper-epoxy were prepared by vacuum casting process. Space charge characteristics have been studied by the method of pulsed electroacoustic (PEA) technique at different electric fields and temperatures, including charge polarity, charge amount,...
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