中文摘要：

用费克（Fick）第二扩散定律推导油纸绝缘中微水扩散的方程，通过分析边界条件并用数值分析法求解该偏微分方程，得到不同时刻绝缘纸中微水浓度随厚度变化的分布曲线，通过对这些分布曲线的积分计算获得绝缘纸中平均微水浓度随时问的变化曲线，数学分析和实验结果都表明该曲线符合指数函数，但该指数函数的平衡时间受温度、油纸绝缘中微水的稳态浓度、绝缘纸的厚度和透水方式等因素的影响，计算机仿真表明这几种因素对平衡时间的影响是互相独立的。最后通过求取所有单个因素下的平衡时间计算式，综合得到多个因素下的平衡时间的计算方程式。

英文摘要：

On basis of Fick＇s second law, a partial differential equation is designed to analyze the moisture diffusing in the oil-paper insulation. By analyzing the boundary condition and solving the equation, a set of curves for disequilibrium moisture concentration distributing along thick direction in paper at regular intervals are obtained. By integrating the curves, a curve for average moisture concentration in paper changing with time is obtained. Both the numerical calculation and experiment both show the curve is exponent, but the equilibration time is affected by the temperature, the equilibration moisture, the thickness of the paper, and the permeating modes. By the compute simulation, the four effects are validated independent, and the equation for counting the equilibrium time is obtained.