| With the rapid development of urban rail transit, DC Overhead lines are suffering more and more lightning strikes. At the same time, the traditional lightning protection measures are unable to prevent the urban rail transit from being lightning-strike. Therefore we must find new lightning-protection ideas to minimize the probability of lightning-strike to the DC Overhead lines.In this paper, on the basis of previous studies, the basic characteristics of DC arc are being discussed. The theory and practice prove that the strong airflow can drive the DC arc well, and then, exhaustive analysis is made about extinguishing properties of DC arc under the strong airflow. The simulation results of fluid dynamics software also prove that the jet angle has certain influence to the extinction of the arc. In addition, the images captured by high speed camera show the microscopic characteristics of DC arc under the strong airflow.Moreover, based on the above analysis and experiment, a new lightning protection interrupter gap applied on the city rail transit is being developed, which can well suppress the probability of sustained arc. Relevant experiments testify that the new lightning protection interrupter gap can rapidly and reliably put out the DC arc of 750V,1500V. |
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