Méndez Cristina, Olmo Cristian, Renedo Carlos Javier, Ortiz Alfredo, García Diego
Electrical and Energy Engineering Department, School of Industrial and Telecommunications Engineering, Universidad de Cantabria, Avenida Los Castros, 39005 Santander, Spain.
School of Electrical and Electronic Engineering, Universidad del Valle, Cali 760032, Colombia.
Polymers (Basel). 2024 Apr 25;16(9):1196. doi: 10.3390/polym16091196.
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.
当矿物油作为变压器的冷却剂时，在各种运行条件下，其固体绝缘状况是决定变压器使用寿命的主要因素，这一点广为人知。然而，目前有一种趋势是用可生物降解的流体，特别是酯类来替代这种油；因此，了解这些流体作用下固体绝缘的老化情况至关重要。目前可得的数据无法在市场上现有的酯类中选出最佳的，因为每项研究应用的条件不同，使得结果无法进行比较。因此，本文分析了牛皮纸和热升级牛皮纸在以下五种最具前景的商用酯类作用下的降解情况：葵花籽油、菜籽油、大豆油、棕榈油和合成酯。这些材料在130℃、150℃和170℃下进行了加速热老化，并通过其聚合度和获得降解动力学模型来评估纸张的完整性。这项工作中研究的材料种类广泛且都经过相同处理，这使得能够对酯类进行比较，揭示了替代流体在影响方面的显著差异。葵花籽油、菜籽油和大豆油酯提供了最佳的纸张保护，即在150℃的测试中，使用这些流体时牛皮纸的聚合度下降了71%，相比之下，使用矿物油时下降了83%，使用棕榈油酯时下降了79%，使用合成酯时下降了75%。此外，还获得了不同的动力学模型来预测降解情况；得出的结论是，埃姆斯利模型拟合效果最佳。此外，还发现一种介电流体与一种纸张的作用情况不能外推，这一点只有在广泛的研究中才会明显体现。
