空间电荷与直流电导联合测试技术用于纳米MgO抑制XLPE中空间电荷的研究

粒径70nm的MgO以不同浓度与交联聚乙烯(XLPE)共混制成聚合物纳米复合介质。采用自主研发的四电极系统同时测量复合介质的高场电导特性和空间电荷分布。通过强场电导实验发现,在室温下,XLPE及纳米MgO/XLPE复合介质的电导机理不是单纯的空间电荷限制电流(SCLC)。此外,添加纳米MgO可以明显地提高空间电荷的注入阈值,并且在低于空间电荷注入阈值的电场下,复合介质的电导电流密度随纳米MgO浓度的增加,先减小后增大。最后从空间电荷的实验数据验证了纳米MgO能有效抑制XLPE中空间电荷,并进一步定性地认为纳米Mgo的添加提高了电子注入的电场强度阈值。

Research on the Space Charge Suppressing Mechanism of Nano-MgO in XLPE with a Joint Measuring Technology of DC Conduction and Space Charge

The nanocomposite is produced by adding different concentrations of nano-MgO,whose particle size is 70nm,to cross linked polyethylene(XLPE).The high field conduction and space charge distribution of samples are studied with a jointing measuring apparatus of dc conduction and space charge.It is found that the conduction mechanism of XLPE and the composites of nano-MgO/XLPE are not dominant by space charge limited current(SCLC) at the room temperature.At the same time,space charge injection threshold of the samples was calculated.It is shown that the addition of nano-MgO could increase the threshold 30.69% higher than that of pure XLPE.Moreover,it is found that the dc conduction of nano-MgO/XLPE decreases firstly and then increases with the increment of nano-MgO content as dc electrical stress is below the injection threshold.Space charge distribution in all samples is investigated and it is found that nano-MgO could well decrease the hetero-charge accumulation and inhibit electron injection in XLPE.