This research employs a high temporal resolution particle imaging velocimetry system to observe the entire bridging process of cellulose particles in insulating oil from a microscopic perspective. The analysis focuses on the particle dynamic behaviors that play a significant role in bridging and provided an in-depth elucidation of the bridging mechanism. By analyzing the motion characteristics of cellulose particles, mechanisms including charging, polarization, charge transfer, and inter-particle interactions were discussed. The space charge polarization effect of charged cellulose particles (SPCP) was discovered, leading to the development of a cellulose particle dynamic model that incorporates SPCP. This model provides a rational explanation for the observed dynamic behaviors of cellulose particles and holds the potential to become a fundamental theoretical in the field of liquid dielectric impurity particle contamination.

This study presents a novel method for measuring the collisional charge of micron-sized particles in insulating oil. Specific studies involves measuring the charge of micron carbon particles and cellulose particles in insulating oil and fitting the data to develop calculation formulas for collisional charge under various charging modes. The developed formulas provide crucial charge data to study impurity particle migration and aggregation in oil-immersed power equipment. The study also examines the impact of wall material, particle size, and electric field intensity on the collisional Charging Characteristics of particles. The collisional charge of particles is proportional to their surface area. As the electric field is strengthened, the collisional charge will tend to saturate. Furthermore, the polarity of the collisional charge of particles has been summarized. The measurement method proposed in this study has an error of approximately ±3.5% and performs well in measuring the collisional charge of micron-sized particles in liquid media.

Transformer oil will inevitably be contaminated by impurity particles in the actual operation process; Carbon particles are the most abundant conductive particles in transformer oil. The adhesion behavior on the internal insulating surface will cause electric field distortion, which will pose a serious threat to the safe and stable operation of oil-immersed power equipment. To this end, this paper builds an experimental platform for simulating the adhesion behavior of carbon particles in transformer oil, studies the adhesion characteristics of carbon particles, and analyzes the influence of electric field, particle size, oil flow velocity, and other factors on the adhesion of carbon particles. The results show that: the DC electric field is the main factor driving the adhesion of carbon particles on the surface of epoxy resin (with the increase in electric field strength, the degree of adhesion of carbon particles firstly rises and then decreases); the smaller the size of the carbon particles, the easier it is to adhere, and the corresponding electric field strength is different for different sizes of carbon particles when the degree of adhesion is the largest; the velocity of the transformer oil will have a significant impact on the adhesion behavior of the carbon particles (with the increase in the flow velocity, the degree of adhesion of carbon particles firstly rises and then decreases). The research conclusion of this article is helpful in guiding the evaluation of insulation performance and the optimization of insulation structure design in the converter transformer valve-side bushing considering the phenomenon of particle adhesion.