油浸层压纸板在低场强下空间电荷的积聚特性

Accumulation Characteristics of Space Charge in Oil Impregnated Pressboard with Lower Electrical Field

换流变压器油纸绝缘系统中大多采用较厚的层压纸板,但目前有关较厚纸板的空间电荷积聚特性的研究较少。为此,利用脉冲电声法(PEA),研究了低场强(<5kV/mm)较厚纸板(0.5～2mm)中电荷的积聚特性,以及水分质量分数和温度因素对油浸层压纸板空间电荷积聚特性的影响,并采用热刺激电流法(TSC)研究了不同厚度油浸纸板空间电荷积聚特性的差异。研究发现,层压纸板中的水分质量分数对空间电荷的积聚影响显著,当质量分数在0.9%～3.5%范围内时,空间电荷随着水分质量分数的增加而线性增加;温度对空间电荷的影响也很明显,当纸板温度升高到333K时,其相同时间内积聚的空间电荷密度峰值是273K时的4倍。纸板厚度对其电荷积聚的影响规律和机理还需要进一步研究。

Using the pulse electroacoustic （PEA） method, we investigated accumulation characteristics of space charge and influential factors（mass fraction of water and temperature） in oil-impregnated thick pressboards （0. 5-2mm thick） under low electrical field values （〈5 kV/mm）. Moreover, we adopted the thermoelectric stimulated current（TSC） to analyze the different influences of various pressboard thickness on the accumulation characteristics of space charge. The results show that, the mass fraction of water in pressboards has a great influence on the charge accumulation; when the mass fraction ranges within 0.90% -3.5%, the space charges is linearly increased. Temperature also has a great effect on the charge accumulation： when the temperature of pressboards is 333 K, the peak of charge density is 3 times more than that under the temperature of 273 K within a same time period.