Study on Bridging Characteristics of Fiber Particles in Flowing Insulating Oil Under DC Electric Field

This article investigates the bridging behavior of fiber particles in insulating oil under the background of a flow-electric coupled field, which is of great significance for explaining the micro-discharge and the deterioration of the overall electrical properties of insulating oil in a transformer. Based on the observation experiments, a constructed oil circulation device and shooting system is used to study the bridging characteristics of fiber particle swarm in oil flow under a dc electric field. The effects of electric field intensity, oil flow velocity, and mass fraction of particles in oil on the bridging process are analyzed in detail, and the changes of conduction current between electrodes under different conditions are recorded. The results show that the bridging behavior of the fiber particle swarm is the result of the combined action of the flow field and electric field. The forces provided by the electric field on the fiber particles cause them to aggregate and bridge between electrodes, and with the increase of field intensity, the bridging speed increases significantly. The influence of flow velocity is more complicated, and it has different effects on the bridging process of particles under low and high field intensity. The mass fraction of fiber particles in oil is negatively correlated with the difficulty of bridging between electrodes. Finally, the bridging mechanism is explained from the perspective of the forces on particles and electric field distortion, and the variation characteristics of conduction current between electrodes are analyzed.