Analysis of the Dispersion of Insulator U_50% Considering the Influence of Waveform and Altitude

This paper investigates the impact of standard and short-tail impulse waves on the discharge voltage of insulators at different altitudes. Through experiments conducted in both plain and high-altitude regions, the U50% discharge voltage was recorded using the up-and-down method, and the normality of the discharge voltage was assessed by the Shapiro-Wilk test. The dispersion of discharge voltage under various conditions was then analyzed. The study finds a strong linear relationship between the dry arc distance and the $\boldsymbol{U}_{50 \%}$ discharge voltage under standard wave impulses. In high-altitude regions, the normality rate of positive polarity standard waves ($\mathbf{4 5 . 4 5 \%}$) is higher than that of positive polarity short-tail waves. Additionally, the normality rate in plain regions (54.55%) exceeds that in high-altitude regions. The results demonstrate that discharge voltage dispersion is greater at high altitudes and under short-tail wave impulses. These findings contribute to a deeper understanding of the discharge processes of insulators in different environments and conditions, and provide crucial data support for the lightning protection design of transmission lines.