造纸用水电导率对油纸绝缘电气特性的影响

Electrical Properties of Oil-paper Affected by Water Conductivity During Paper-making Process

水在纸的制造过程中发挥了关键作用。为探究水电导率对油纸绝缘电气性能的影响,分别利用电导率为3μS/cm的纯净水和电导率为100μS/cm,500μS/cm和1 000μS/cm的氯化钠溶液制备绝缘纸,进而得到油纸试样。对所得试样,测试电导电流、体积电阻率、介电特性和击穿特性。结果表明:随着造纸用水电导率的增加,油纸试样的电导电流上升,体积电阻率下降,介质损耗角正切值增大;交流击穿场强没有显著变化而直流击穿场强从90 kV/mm下降到72 kV/mm。利用离子色谱仪分析绝缘纸中钠离子和氯离子的质量分数,发现离子质量分数随水电导率的增加而升高。由此得出,造纸过程中随着水电导率增加,纸中残留的离子含量增加,从而引起油纸绝缘部分电气性能的变化。

Water plays an essential role in paper-making process. In order to investigate the effects of water conductivity on the electrical property of oil-paper, we prepared kraft paper samples with pure water of 3 μS/cm and sodium chloride solutions of 100 μS/cm, 500 μS/cm and 1 000 μS/cm respectively, and used these samples to make oil-paper specimens after vacuum impregnation. Then we measured the polarization current, volume resistivity, dielectric property and breakdown property of the oil-paper samples. The results show that as water conductivity increases, polarization current increases, volume resistivity deceases, dielectric loss factor increases, AC breakdown field changes little, and DC breakdown field decreases from 90 kV/mm to 72 kV/mm. We also used ion chromatography to analyze sodium ion content and chloride ion content in the kraft paper samples： both of them increase as water conductivity increases. It is suggested that in making process, increasing water conductivity will increase ion content in kraft paper and hence cause electrical properties variation of oil-paper insulation.