Study on Kinetic Behavior and Adsorption Mechanism of the Micron Metal Dust Near the Basin-type Insulator in DC GIL

摘要

Metal dust of micron level is often generated in DC GIS/GIL, probably causing serious faults such as surface flashover of insulators. In this paper, a semi-closed coaxial cylindrical electrodes platform was built as to study the movement behavior and adsorption mechanism of the micron metal dust near the basin-type insulator, and unique phenomena were obtained. Firstly, two adsorption modes of dust were discovered. One is "accumulative adsorption" on the insulator, and the other is "diffusive adsorption" towards the high-voltage electrode and grounded electrode. Then, some special phenomena were observed. For accumulative adsorption, an obvious "polar effect" was found. The adsorbed range is wider, the adsorbed amount is larger and the adsorbing time is shorter when under negative voltage. And a "maximum value" of accumulative amount is found as voltage is increased. What’s more, the increase in amount of dust and voltage may lead to "explosion" of the metal dust. To account for the experimental phenomena, a stress analysis model under multi-physical fields were established. In the "V" shaped area formed by the insulator surface and dust heap, effects of electric field forces on dust particles cancel each other out. Hence, the key to accumulative adsorption turns to be the coulomb force of surface charge in insulator on charged particles. While the polarity of surface charge in insulator contributes directly to the polarity effect of accumulative adsorption. The main factor on diffusive adsorption lies in the distorted electric field force on the charged dust, and repulsion between them makes the distribution uniform. Finally, This paper considered that interaction between coulomb force and distorted field force causes the "maximum value" of accumulative adsorption. However, the mechanism of all special motion behavior remain to be further studied.