Metal Particle Movement Behavior under DC Voltage: The Influence of Surface Charges Accumulating on a Truncated Insulator

Metal particle contamination is a critical factor killing the security of DC insulation system. The movement process of metal particle becomes complicated under DC voltages due to the existence of accumulated charges on insulator surface. In order to obtain the correlation between the surface charges and metal particle behavior, a metal particle movement simulation model is established. The metal particle lifting voltage is both measured experimentally and calculated by simulation, and the little difference demonstrates the effectiveness of the simulation model. Then the effects of surface charges on a truncated insulation with different polarities on the metal particle motion characteristics are investigated. The influence mechanism of surface charges on particle movement is revealed. The results show that the homo-charges increase the electric field near the grounded electrode. After colliding with electrode near high-field region, metal particle carries more charges, leading to a reduction in the lifting voltage. However, when the amounts of homo-charges reach a certain level, metal particle tends to move towards the insulator. Conversely, hetero-charges increase the particle lifting voltage and enable it to move away from the insulator. Besides, the electrode roughness changes the random reflection angle of the metal particle after colliding, making the motion characteristics of metal particle more complicated. We hope this study could deepen the understandings of interaction between surface charges and metal particle movement.