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Transformer development is limited to smaller sizes and larger capacities due to two major shortcomings: first, the solid insulation that is used in an oil-immersed transformer, which is generally cellulosic paper, cannot resist high temperatures, and second, the significant difference in the dielectric constants between the cellulose paper and the transformer oil will lead to an uneven electric field...
The dielectric constant and the high temperature resistant performance of solid insulation used in oil-immersed transformer would limit the capacity and size of an oil-immersed transformer. In this paper, kraft paper and polycarbonate has been aged under 90 °C, 110 °C and 130 °C up to 300 days, simultaneously an electric pre-stressing of 3kV/mm is performed. The dielectric spectroscopy (here refer...
The poor thermo stability and electrical properties of insulation paper used in an oil-immersed transformer would limit the performance and size of the transformer. In order to substitute insulation paper, we chose polyphenylene sulfide (PPS) as the object of study to make research on its electro-thermal aging characteristics. We tested PPS's dielectrical, physical, chemical and mechanical properties...
Traditionally, oil-filled transformers have utilized cellulose paper as primary insulation. However, cellulose insulation is a relatively low temperature material and thermal degradation due to overload conditions and long-term aging can lead to transformer failures, Therefore, it restraints the development of high density power transformers. What's more, since the transformer oil has a relative dielectric...
Material's micromechanism determines its property, therefore we should research on polymer material's micromechanism so as to further explain its insulation characteristic. From material's infrared spectrum, main function groups can be found through the wave numbers of absorption peaks. In the experiment five kinds of polymer materials, which are kraft paper, PC, PET, PTFE and PPS, are aged in the...
This paper measured the dielectric properties of the kraft paper and three polymer materials before and after electro-thermal aging, the examined dielectric parameters are ac electric breakdown strength, dielectric constant and dissipation factor. Preliminary results show that under the same aging time, as the aging temperature rises, the dielectric strengths of kraft paper, PPS, PC and PET are not...
Traditionally, oil-filled transformers have utilized densified cellulose paper as the primary conductor insulation. However, cellulosic insulation is a relatively low temperature material and thermal degradation due to overload conditions and long-term aging can lead to transformer failures. In order to improve the structure and insulation performance of oil-filled transformers, this paper choose...
The transmission characteristics of the PD signal and the interference signals in the cross-bonding link-system of XLPE cable was researched by experiment based on the cross-bonding link-system of cable made exactly according to the real engineering system where the PD detection is initialized in the cable accessories. The experimental results showed that the PD signal can be distinguished from the...
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