水分对油纸绝缘热老化速率及热老化特征参量的影响

Influence on the Thermal Aging Rate and Thermal Aging Characteristics Caused by Water Content of Oil-Paper Insulation

本文设计了在110℃和130℃下初始含水量分别为1%、3%、5%的绝缘纸试品在变压器油中的老化试验。系统地研究了不同初始含水量对油纸绝缘热老化速率的影响,分析对比了老化过程中的绝缘纸聚合度、纸中含水量、油中含水量、油中糠醛含量、油中酸值等老化特征参量的变化趋势。研究结果表明:初始含水量从1%增长到3%的绝缘纸平均降解速率的增长率比初始含水量从3%增长到5%时大得多,且从3%增长到5%时降解速率的增长率已经很小,有趋于饱和的趋势;老化过程中油中水分与纸中水分均是波动的,二者的波动幅度有较好的正相关关系,且二者整体上波动趋势的关系与初始含水量有关;水分含量及其变化趋势能影响老化过程中糠醛、酸等老化特征产物的变化趋势。因此本文提出应根据整个老化过程中油、纸二者水分含量整体上波动趋势的关系及波动幅度的大小来对变压器油纸绝缘进行状态评估及受潮分析,并建议在根据传统的油中糠醛、酸值等老化特征参量来对油纸绝缘进行状态评估及故障诊断时需充分考虑水分的影响。

In this paper, a aging test is designed, in which the insulating papers with the initial moisture contents of 1%, 3%, 5% were aged in transformer oil at ll0~C and 130~C respectively. The influences of the different initial moisture contents on the oil-paper insulation thermal aging rate are studied systematically. This paper also analyes the variation trends of some aging indicators including degree of polymerization of insulation paper, water content in paper, and water, furfural, acid content in oil during the aging process. The results indicate that, water can accelerate thermal aging rate of the oil-paper insulation, and the lower the temperature the greater the impact factor of water content to accelerate aging. The water content in both oil and paper are fluctuant during the aging process, the fluctuation amplitude in oil and paper have a good positive correlation, and the relationship is related to the initial moisture content. Water can affect the proliferation and the distribution ratio of the aging characteristic products such as furfural and acid in the oil-paper system. Therefore, to make the assessment insulation state and insulation damp effect more accurate, this paper suggests that the globalrelationship of the fluctuations trend between oil and paper water content and the fluctuation amplitude should be take into consideration, as well as the impact of water when using the traditional characteristic parameters such as furfural, acid in oil to assess the oil-paper insulation state and fault diagnosis.