590 / 2022-03-30 15:56:00

DC Break-Up Performance of Water Streams in Rod-Plane Short Air Gap under Heavy Rain Conditions

Rain conditions; DC discharge; short air gap; water streams break-up performance; finite element simulation; simula-tion experiment

 The occurrence of heavy rain may cause rain streams on transmission lines, towers and insulator strings, which will shorten the insulation distance of the air gaps among transmission equipment, causing raining flashover fault. In order to study the break-up performance of the water streams and its influence on the discharge characteristics, this paper focuses on the DC discharge characteristics of rod-plane short air gap. The results indicate that the break-up process of the water streams in rod-plane short air gap is mainly affected by external electric field force, surface tension of rain stream and viscous force. The electric field force is as same as surface tension, which promotes water streams breaking up. The break-up of water streams goes through three stages in turn:  jet zone, transition zone, break-up zone. The break-up length of water streams decreases with the increase of applied voltage under different flow velocities, but the decreasing trend becomes slower. The critical length of the water streams increases with the increase of the velocity. In addition, the break-up diameter decreases with the increase of applied voltage, and the change rates are positively correlated with the diameter of water streams. By comparing the simulation results with the test results, the break-up diameter and length have the same variation trend with rainfall intensity and voltage. The deviation of the data of break-up diameter is about 10%, and the deviation of break-up length is within 15%. The research results can provide theoretical support for transmission line design and insulation selection.