低气压下不同伞型结构复合绝缘子交流污闪性能对比

Comparison of AC Pollution Flashover Performances for Composite Insulators with Different Configuration Under Low Atmospheric Pressure

为得出高海拔、低气压污秽地区污闪性能优异的复合绝缘子技术参数,在大型多功能人工气候室内对高海拔、低气压条件下干弧距离比较接近的4组不同伞型结构的复合绝缘子(共7种)的污闪性能进行了对比研究。分析了复合绝缘子技术参数、污秽度对气压影响特征指数n及污闪梯度EL的影响。结果表明,气压特征指数n介于0.55～0.88之间,且随着污秽程度加剧而变小;在一定的结构高度下,n随着复合绝缘子伞间距与伞伸出之比S/P减小而增大,随伞裙边缘两点之间爬电距离与直接空气间隙距离之比l/d增大而增大。在低气压、污秽共同作用下,大小伞型爬距与干弧距离之比L/h为3.55的复合绝缘子在海拔≤2500m时污闪梯度EL最大,耐污性能最佳;海拔高度达4000m、大小伞型L/h为3.27时污闪梯度EL最大,耐污性能最佳,最佳L/h有随气压降低而变小的趋势。

In order to find out the optimal configuration of composite insulator under high altitude and pollution region,laboratory comparison studies were carried out on the pollution flashover performance of four configurations composite insulators （the number is seven in all） in the big multi-function artificial climate chamber. The influences of configuration parameters,salt deposit density （SDD） and atmospheric pressure on the characteristic influence exponent n of air pressure and flashover gradient EL of the test samples were analyzed. It is shown that the characteristic influence exponent n is between 0.55 and 0.88 determined by the SDD and configuration parameters of composite insulators. The characteristic influence exponent n will decrease as the SDD increasing,will increase as the ratio of the distance of nearby umbrella and spread distance of umbrella （S/P） decreasing,and will increase as the ratio of the creepage distance and geometrical distance of the two points on the edge of umbrella increasing. The big-small umbrella configuration composite insulator with the 3.55 CF coefficients （ratio of creepage and dry-arc distance） has the biggest EL and optimal pollution performance under the 2500 m altitude. When the altitude reaches 4000 m,the same umbrella configuration composite insulator with the 3.27 CF coefficients have the best pollution performance. There is a general tendency of the smaller value of the optimal CF for higher altitude.