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RISS 인기검색어
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- 저자 : Feng Changhui (검색결과 3 건)
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Yongqiang Wang,Changhui Feng,Yu Luo,Ruoyu Fei 한국섬유공학회 2020 Fibers and polymers Vol.21 No.11
To study the variation of surface characteristics of glass fiber reinforced epoxy composite insulation materialsduring the development of tracking, this paper established an experimental platform for tracking under the inclined platemethod and prepared samples of glass fiber reinforced epoxy resin. In this paper, according to the experimental dischargephenomenon, discharge repetition rate phase diagram and corrosion degree of materials, the process of tracking was dividedinto four stages: initiation, stability, development and outbreak stages. Scanning electron microscope was used to observe thechange of micromorphology of samples in different stages of tracking. The content of elements in different stages of trackingwas determined by energy dispersive spectrometer. The surface characteristic functional groups in different stages of trackingwere measured by Fourier transform infrared spectroscopy. The results show that with the change of surface morphology andthe formation of surface products during tracking, the content of C element in the spherical region of the material decreasedfirst and then increased, and the content of O and Si increased first and then decreased. The epoxy group of the material wasgradually decomposed. Carbonyl group was generated on the surface of the material, and then decomposed during theoutbreak stages. In addition, the deterioration mechanism of thermal aging and tracking was quite different. Thermal agingprovided convenient routes for the electron injection into the material during tracking, thus reducing the tracking and erosionresistance of the material.
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Yongqiang Wang,Yu Luo,Changhui Feng 한국고분자학회 2019 Macromolecular Research Vol.27 No.10
This study aimed to investigate the effects of temperature and aging on the characteristic parameters of dielectric spectra of epoxy resin impregnated paper insulation. A broadband dielectric spectra test platform was established and an equivalent physical model of the valve side dry-type bushing of the converter transformer was developed. Different degrees of thermal aging were performed at 130 °C for 0, 4, 8, 16, and 32 days. In addition, variation of the complex permittivity and dielectric loss factors of epoxy resin impregnated paper at different temperatures and different degrees of aging was revealed. The dielectric spectra test results were fitted using the Havriliak-Negami (HN) relaxation model. The characteristic parameters were extracted, and the influences of temperature and aging on the characteristic parameters of the HN model were analyzed. The results show that in the low frequency range, temperature and aging exert greater influences on the complex permittivity. In the high frequency range, temperature and aging have smaller effect. The relaxation time and temperature satisfy the relationship of the Arrhenius equation, and the relaxation strength increases exponentially with increasing temperature. The relaxation time τ, the relaxation intensity Δε, the shape parameter α, and the shape parameter β can characterize the aging degree of paper insulation. A linear relationship between relaxation and aging times, and an exponential relationship between relaxation intensity and aging time were revealed.
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Wang Yongqiang,Liu Han,Feng Changhui,Guan Jie,Geng Yicheng 한국섬유공학회 2019 Fibers and polymers Vol.20 No.10
Electric tree aging due to the action of long-term partial discharge stress of epoxy resin casting insulation is amajor problem in electrical engineering. On the discharge experimental platform, initiation and culture experiments of theelectric trees were carried out at a power frequency voltage of 20 kV. The mass fractions of the spherical glass fibers were 0,0.5, 1, 2 and 3 %. The results showed that the electrical dendritic process of epoxy resin experienced initiation, growth, lagand burst periods, the phase maps of the corresponding partial discharges in the four periods were all “mountain-like”. Theelectric tree of pure epoxy resin showed a typical dendritic structure, after the glass fiber was properly added, the electric treebecame lighter in color with a more complicated shape, the damage also became more serious, however, the growth of theelectric branch was suppressed. The electric tree aging channel of the epoxy resin appeared black and under microscopy themicro-branched channel wall appeared white. When the amount of glass fiber was 2 %, the initiation time of the electric treeswas prolonged, the growth rate of the electric trees decreased and suppressing development of the electric tree branches wasoptimal.
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