Flow Field and Collision Characteristics of Contaminated Solid Particles on Outdoor Insulators

External insulator is one of the essential electrical equipment associated to the protected and secure operation of the electrical system. Therefore, it is very necessary and important to find out about the defects of external insulators, especially dirty lightning. This paper used Fluent software to set up a hydrodynamic model of outdoor insulators.By checking the air distribution around the isolator, the relationship between collision rate and wind speed, particle size and concentration is analyzed. The results show that the particle deposition deteriorates with the increase of particle concentration, but the collision velocity usually remains unchanged. The gravitational sedimentation effect and collision rate both increase with the increase of particle size.However, when the size of solid particles is too large and at low wind speed,the insulator surface cannot be reached, and in this case, the collision rate will decrease.