DC Arc Numerical Calculations and Experimental Researches Based on the Arcing Horn Used in Over-head Line

Arcing horn, which is a kind of rod-rod air gap, is usually parallel-installed on the insulator in the over-headlines in order to protect the insulator from being burnt by the fault arc. However, if the fault arc cannot be interrupted by the arcing horn in time, it will cause the operation of DC transmission systems unstable. So, it is necessary to do some researches on the characteristics of arc motion. Here, a magneto hydro dynamic (MHD) model was built to simulate the arc moving behaviors, as well as the mathematical model for dynamic DC arc in the arcing horn was analyzed. Three kinds of airflows, such as the cross-wind, the non-wind and the wind in 45° direction, were simulated to demonstrate the effects of airflows on the arc moving behaviors. The arc temperature, voltage, current and resistance were presented according to the MHD simulation model. Finally, some experiments were made to compare with the simulation results. Experimental results verify that the MHD simulation model is correct. The arc temperature is as high as 9000 K and it is not significantly different during the various evolution processes. The direction of airflow has much influence on the arc moving behaviors under three different conditions. The arc voltage and resistance are gradually increased while the arc current is decreased after 250 ms. This paper is useful for the researches of DC arc movement in the arcing horns.