Motion Characteristics of Cellulose Particles in Oil—Analysis of the Synchronized Interframe Imaging and Voltage Observations

The movement and aggregation of cellulose particles reduce the insulation performance of the transformer, thereby increasing the risk of oil-paper insulation failure. In this study, an experimental platform is constructed to synchronously record the particle motion images and voltage, allowing for the observation of the typical motion mode of the particle between electrodes, namely, the back-and-forth motion mode, under alternating current (ac) voltage. The connection between the cellulose particle’s movement and the ac voltage phase in this motion mode is subsequently examined, delving into the trajectory of particle motion, which is captured through the implementation of image processing technology. The results indicate that the cellulose particle does not always move in the direction of the electric field lines. Within one cycle of the power frequency voltage waveform, the particle exhibits two states: staying on the electrode surface and moving in the oil gap, with each state occupying approximately half of the time. In addition, the cellulose particle consistently moves within the oil gap during the second and fourth quadrants of the voltage cycle, while it remains on the electrodes during the first and third quadrants. Subsequently, an analysis model is conducted to simulate the particle’s trajectory as it moves between the electrodes, coupled with the calculations and analysis of the variation in the velocity and the primary forces exerted on the particle. The results show that the particle tends to move toward the more concentrated area of the electric field, and the closer it is to the center of the spherical electrode, the denser its motion trajectory is. This study provides a theoretical basis for the subsequent insulation hazard assessment of cellulose impurities.