应用油中酸值评估不同老化程度绝缘纸中水分含量

Evaluation of Water Content in Insulation Paper of Different Aging Degrees Using Acid Value in Oil

变压器油纸绝缘老化会影响水分在油纸中的分布情况,为此,应用绝缘油中酸值作为老化的特征参数以定量描述老化对水分分布的影响。对4组油纸绝缘试样进行不同程度的加速热老化试验,结果表明:油纸绝缘老化导致油中水分的饱和溶解度不断增加,并促使绝缘纸中水分向绝缘油中转移。根据试验测量结果,引入与油中酸值相关的平移因子m,建立了绝缘油中水分饱和溶解度与油中酸值和温度的数学表达式;根据Freundlich等温吸附方程式建立了绝缘纸中水分质量分数与油中水分质量分数、油中酸值和温度的数学表达式,拟合得到吸附平衡常数c和系数n与温度的关系式。应用以上研究成果可以更准确有效地评估不同老化程度的绝缘纸中水分质量分数,具有重要工程应用价值。

Aging affects the internal water distribution in oil-paper of transformer. Thus, using the acid value in oil as a characteristic parameter of aging, we described the influence of aging on water distribution. Meanwhile, we carried out accelerated thermal aging tests on four groups of oil-paper insulation samples, and found that aging of oil-paper insulation would increase the water saturation in oil and prompt the water transportation from paper to oil. According to these results, we introduced a shifting factor m related to acid value in oil to establish a mathematical expression involving acid value in oil, temperature, and water saturation in paper by the Arrhenius equation, and established a mathematical expression in- volving water content in paper, acid value in oil, temperature and water content in paper by the Freundlich adsorption equation. Then we obtained the fitting relationship between adsorption equilibrium constant c, coefficient n, and tempera- ture. The water content in papers of different aging degrees could be evaluated accurately by using the results mentioned above.