应用时–温–水分叠加方法改进油纸绝缘热老化寿命模型

Improvement of Lifetime Model on Thermal Aging of Oil-paper Insulation by Time-temperature-moisture Superposition Method

为改进现有的油纸绝缘热老化寿命模型,使模型的预测结果更为准确,研究初始水分含量及温度对油纸绝缘试品的加速热老化特性影响。首先,对4种初始水分含量的油纸绝缘试品分别在3个温度下开展加速热老化试验,以绝缘纸聚合度作为表征老化程度的特征参量,引入纤维素累积损失动力学方程研究其在老化过程中的变化规律;其次,在时温叠加方法基础上提出一种时间–温度–水分叠加的新方法,并改进了热老化寿命评估模型。结果表明,与之前的寿命模型相比,改进的模型不但考虑了温度对绝缘纸热老化速率的影响,而且考虑了不同初始水分含量对油纸绝缘热老化的加速作用,有助于对油纸绝缘的热寿命进行更为合理的评估。

In order to improve the lifetime model of oil-paper to obtain the more accurate prediction results,the influences of initial moisture contents and temperatures on aging properties of oil-paper was investigated.Firstly,oil-paper samples with four different moisture contents were aged at three temperatures.Degree of polymerization（DP） of paper was measured as indicator of aging degree.The variation of DP with aging time was studied by introduction of kinetic equation of cellulose degradation accumulation.Secondly,based on the time-temperature superposition（TTSP） method,a time-temperature-moisture superposition（TTSMP） method was proposed to improve the lifetime model.It demonstrates that by comparing with previous lifetime model,the merit of the improved one is that not only temperature but also initial moisture content are considered,which is helpful for making more rational estimation of insulation lifetime during long time aging.