Temperature and humidity are the main factors that cause the decomposition of Nomex paper widely used as turn-to-turn insulation material of mining dry-type transformers. In this study, for understanding the effect of ambient humidity and thermal aging on the properties of Nomex paper, specimens with the initial moisture content of 7% were aged in the oven for 168, 504, 672 h at 180°C, respectively. After thermal aging, corona discharge experiments of unaged and aged specimens with different aging degrees were carried out at different relative humidity (RH) levels from 10 to 70%. The characteristic parameters of corona discharge, such as the average discharge amplitude and the number of discharges, were measured. Then, the surface conductivity and the surface potential decay rate were measured. The morphology and attenuated total internal reflectance Fourier transform infrared spectroscopy were also analysed for explaining the difference of properties between unaged and aged specimens. The experiment results indicate that the average discharge amplitude decreases with the increase of RH or the deepening of the aging degree of specimens, but the number of discharges shows the reversal tendency. The changes in the physical structure and chemical composition, which is induced by the hydrolysis reaction of Nomex paper, accelerate the surface potential decay and increase the surface conductivity.

温度和湿度是导致Nomex纸分解的主要因素，该纸被广泛用作采矿干式变压器的匝间绝缘材料。在这项研究中，为了解环境湿度和热老化对Nomex纸性能的影响，将初始水分含量为7％的样品分别在180°C的烤箱中老化168、504、672 h。热老化后，在10％至70％的不同相对湿度（RH）水平下，对不同老化程度的未老化和老化试样进行电晕放电实验。测量电晕放电的特征参数，例如平均放电幅度和放电次数。然后，测量表面电导率和表面电势衰减率。还分析了形态和衰减的全内反射傅里叶变换红外光谱，以解释未老化和老化试样之间的特性差异。实验结果表明，平均放电幅度随相对湿度的增加或试样老化程度的加深而减小，但放电次数呈逆趋势。由Nomex纸的水解反应引起的物理结构和化学组成的变化加速了表面电势的衰减并提高了表面电导率。实验结果表明，平均放电幅度随相对湿度的增加或试样老化程度的加深而减小，但放电次数呈逆趋势。Nomex纸的水解反应引起的物理结构和化学组成的变化，加速了表面电势的衰减并提高了表面电导率。实验结果表明，平均放电幅度随相对湿度的增加或试样老化程度的加深而减小，但放电次数呈逆趋势。Nomex纸的水解反应引起的物理结构和化学组成的变化，加速了表面电势的衰减并提高了表面电导率。