电力变压器的寿命,主要由其固体绝缘的条件决定,当矿物油是这些机器中的冷却剂时,在各种操作条件下是众所周知的。然而,有一种趋势是用可生物降解的液体代替这种油,尤其是酯类;因此,了解固体绝缘与这些流体的老化是至关重要的。目前可用的数据不允许在市场上可获得的酯中选择最佳酯,因为每一项研究都适用不同的条件,无法比较结果。因此,本文分析了以下五种最有前途的商业酯对牛皮纸和热升级牛皮纸的降解:向日葵,油菜籽,大豆,棕榈,和合成。材料在130、150和170°C下进行加速热老化,并通过其聚合度和降解动力学模型的获得来评估论文的完整性。在这项工作中研究了广泛的材料,接受了相同的治疗,允许比较酯,揭示了替代流体影响的显著差异。向日葵,油菜籽,大豆酯提供了最好的纸张保护,即,在150°C的测试中,牛皮纸的聚合度用这些液体降低了71%,与矿物油减少83%相比,用棕榈酯减少79%,和75%的减少与合成酯。此外,获得了不同的动力学模型来预测降解;结论是Emsley模型提供了最佳拟合。此外,发现一种类型的纸张的介电流体的行为不能外推,这只在广泛的研究中值得注意。
The lifespan of an electrical transformer, primarily determined by the condition of its solid insulation, is well known under various operating conditions when mineral oil is the coolant in these machines. However, there is a trend toward replacing this oil with biodegradable fluids, especially esters; therefore, an understanding of the ageing of solid insulation with these fluids is essential. Currently available data do not allow for the selection of the best ester among those available on the market, as each study applies different conditions, making it impossible to compare results. Thus, this paper analyses the degradation of Kraft and Thermally Upgraded Kraft papers with the following five most promising commercial esters: sunflower, rapeseed, soybean, palm, and synthetic. The materials underwent accelerated thermal ageing at 130, 150, and 170 °C, and the integrity of the papers was evaluated through their polymerisation degree and the obtaining of the degradation kinetic models. The wide range of materials studied in this work, which were subjected to the same treatments, allows for a comparison of the esters, revealing significant differences in the impact of the alternative fluids. Sunflower, rapeseed, and soybean esters provided the best paper protection, i.e., the degree of polymerisation of Kraft paper in the tests at 150 °C decreased by 71% with these fluids, compared to the 83% reduction with mineral oil, 79% reduction with palm ester, and 75% reduction with synthetic ester. Furthermore, different kinetic models were obtained to predict the degradation; it was concluded that the Emsley model provides the best fit. Additionally, it was found that the behaviour of a dielectric fluid with one type of paper cannot be extrapolated, which is only noticeable in broad-scope studies.