Influence of floating dust concentration on AC breakdown voltage of short rod-rod air gap

摘要

The electrical strength of outdoor insulators may decrease and the flashover accidents occurred in the past years. Researchers have carried out the discharge characteristics investigation on outdoor insulators in the sand storm, however it is still necessary to the study the discharge/flashover characteristics in floating dust weather since the investigation is still undergoing and conclusions not fully agreed by the researchers. In this paper, an artificial climate chamber is designed to resemble different dust environment and the breakdown voltage characteristics of typical electrode assignment are discussed carefully. Two diameters of rod-rod electrodes, Φ6 and Φ16 are utilized in the experiment and the concentration of dust in the chamber is controlled in the range of 200-1200μg/m3. The relationships between the breakdown voltage under AC supply with different dust concentration in the electrode system of Φ6 and Φ16 are shown in this paper. From the experiment, it is obvious that the breakdown voltage decreases with the dust concentration in the Φ16 rod-rod electrode system while a minimum value may appear in the Φ6 rod-rod electrode assignment. The possible reason is the present of dust in between the gap may contribute in two ways; the first one is to adsorb free electrons and photons which will increase the breakdown voltage, the other one is to enhance the electrical field in the nearby region which will make the breakdown process easier to develop in contrast. The initial wind speed also has effect on AC breakdown voltage under floating dust weather.