液氮中绝缘体表面形状对沿面闪络电压的影响

Influence of Surface Shape of Insulator Immersed in Liquid Nitrogen on Surface Flashover Voltage

液氮环境下绝缘材料沿面闪络特性的研究是低温高压绝缘技术的重要内容,为得出有效增大爬电距离的方法,研究了液氮环境下绝缘材料的不同表面形状对沿面闪络电压的影响。通过实验测量了爬电距离均为10 mm的不同直径的圆柱形试品、不同斜面倾角的圆台形试品和折线形侧面试品在液氮中的沿面冲击闪络电压,并对试品的电场进行了仿真。实验结果表明:液氮环境中,圆柱型绝缘体直径增加,沿面闪络电压略有下降;不同形状的绝缘体沿面闪络电压有较大差异,其原因是表面形状改变了电场分布,三结合点处场强愈小,绝缘表面电位梯度愈均匀,沿面闪络电压愈高。

The study of surface flashover characteristic of insulation material in liquid nitrogen environment is one of the most important aspects of cryogenic high voltage insulation technique.To attain the approach of effectively increasing creepage distance,the influences of different surface shapes of insulation material immersed in liquid nitrogen on surface flashover voltage are researched.The surface impulse flashover voltage of cylindrical specimens with different diameters, specimens in the shape of circular truncated cones with different obliquities and specimens in the shape of fold line profile,here all specimens are immersed in liquid nitrogen environment and the all creepage distance of them are 10 mm, are measured by experiments,and the electric field distribution on specimen surface is simulated.Experiment results show that in liquid nitrogen environment as the diameters increase of cylindrical specimens,their flashover voltages decrease a little; there are obvious differences of flashover voltages among different shapes of insulator surfaces,and the reason is that the distribution of electric field is changed by surface shape;the electrical field of triple junction is higher,the insulator surface potential gradient distribution is more uniform,the surface flashover voltage will be higher.