Effect of Dark Periods on Subsequent Restrike in the Discontinuous Development of Positive Leader

Research on the physical mechanism of discontinuous development for the positive leader discharge is fundamental for optimizing the external insulation design of transmission lines. The effect of dark periods on the subsequent restrike, as a factor determining the discontinuous development feature, is investigated by means of a current measurement system with a wide dynamic range and direct optical imaging. With the increase of the voltage change rate, the duration of dark periods decreases, and the subsequent restrike is facilitated to occur and end the dark period. In addition, the discharge current and the amount of charge, representing the electrical characteristics, increase in the restrike process with the increase of these electrical parameters in the previous dark period. Two equations are suggested for fitting positive correlations of these parameters in the dark period and restrike processes.