Influence of the high-speed sand dust environment on breakdown characteristics of needle-plate air gap

To ascertain flashover mechanism of the roof external insulation in high-speed airflow environment, breakdown characteristics and mechanisms of short needle-plate air gaps in high-speed airflow were investigated based on an artificial experimental wind-tunnel platform We obtained the breakdown characteristics of the air gaps in wind sand environment by studying the influences of sand mass concentration, wind speed, gap distance and Sand diameter on the breakdown voltage. It is found that the breakdown voltage of air gaps decreases with the increase of the sand mass concentration. When the wind speed increases, the breakdown voltage both in weather of wind sand and in weather of wind appear to be a curve which increases at first and then decreases, and that the breakdown voltage in weather of wind sand is lower than that in other cases. The breakdown voltage decreases at first and then increases with the increase of the sand mass concentration, and there is a minimal value. Research results can provide theoretical basis for roof external insulation protection in high-speed airflow environment.