In insulating liquid, a conductive particle becomes charged through the interaction with a conductor exposed to an applied field. Then, it migrates in the action of both electric field and fluid and causes the enhancement of local field when it is in proximity of the conductor with opposite polarity. The enhancement will lead to partial discharge (PD) and may even ignite full gap breakdown in special cases. This study reviews comprehensive researches relevant to these topics. In the first place, several theoretical methods about how to obtain the charges held by a conductive particle with known potential are introduced, so are experimental methods. Then, forces acting on the charged particle in liquid are classified, and its migration characteristics, as well as influential factors, are described. Subsequently, PD and breakdown mechanisms of liquid initiated by conductive particles are presented. The latter involves two cases: electric-field enhancement when the particle concentration is low and bridging phenomenon when it is high. At last, two important, but frequently ignored factors, i.e. dielectric barrier and oil flow, are highlighted, and the authors’ suggestions for future work are put forward.

中文翻译：

---

绝缘液体中导电颗粒引起的局部放电和击穿研究述评

在绝缘液体中，导电粒子通过与暴露于外加电场的导体相互作用而带电。然后，当它在极性相反的导体附近时，它在电场和流体的作用下迁移并引起局部场的增强。这种增强将导致局部放电（PD），甚至在特殊情况下甚至可能引发全部间隙击穿。本研究回顾了与这些主题相关的综合研究。首先，介绍了几种有关如何获得具有已知电势的导电粒子所保持电荷的理论方法，以及实验方法。然后，对作用在液体中带电粒子上的力进行分类，并描述其迁移特性以及影响因素。后来，提出了由导电粒子引发的PD和液体的分解机理。后者涉及两种情况：当粒子浓度低时电场增强，而当粒子浓度高时发生桥连现象。最后，重点介绍了介电势垒和油流两个重要但又经常被忽略的因素，并提出了对未来工作的建议。