Distribution characteristics of metal particles in flowing transformer oil with paper-covered electrodes

Metal particles are generally regarded as the most hazardous solid particle impurities to the insulation capability of transformer oil. The aggregation of particles in oil channels can cause a significant reduction in insulation performance. However, the distributing characteristic of particles in flowing transformer oil will be changed due to the solid insulation dielectrics. In this paper, the particle distributing observation system was constructed and the distribution images in flowing oil with paper-covered electrodes were observed using a high-speed camera. Simultaneously, the change of leakage current was recorded. Finally, the force conditions of free particles and adsorbed particles were analyzed and the change mechanism of distribution characteristics when the electrode was covered by insulating paper were discussed.