**6. Conclusions**

Many contamination samples collected from porcelain insulator surfaces were measured, and obvious size distribution characteristics were found. Furthermore, an adhesion model was established to analyze the movement of particles, and the influences of different factors on adhesion were also studied. The following conclusions were obtained.


In addition, it can be considered that the size distribution of contaminated particles on the glass insulator surface is similar to that of the porcelain insulator, because glass and porcelain all belong to a rigid medium. However, the surface of a composite insulator will experience micro-elastic deformation during collision, resulting in a difference of the size distribution, so more detailed research about adhesion will continue to be carried out.

**Author Contributions:** Conceptualization, M.Z.; Methodology, R.W.; Software, Y.J.; Validation, M.Z., L.L. and Y.J.; Investigation, L.L.; Resources, L.L.; Data Curation, L.L.; Writing—Original Draft Preparation, R.W. and Y.J.; Writing—Review & Editing, M.Z. and L.L.; Visualization, Y.J.; Supervision, L.L.; Project Administration, M.Z.; Funding Acquisition, M.Z.

**Funding:** This research was funded by the New Theory, New Technology and Application Demonstration of Artificial Rain or Snow Catalyzed by Charged Particles (Project 2016YFC0401002), the Science Technology Program of State Grid Corporation of China (52170216000A), the Fundamental Research Funds for the Central Universities (2016YXZD069) and the National Natural Science Foundation of China (51777082).

**Acknowledgments:** We acknowledge the support given by Ming Lu and Xiaohui Yang, who work in State Grid Henan Electric Power Research Institute (Power Transmission Line Galloping Prevention and Control Technology Laboratory of State Grid, Zhengzhou 450052, China).

**Conflicts of Interest:** The authors declare no conflict of interest.
