带并联间隙地线复合绝缘子直流覆冰闪络特性

架空地线融冰已成为一个亟需解决的问题,目前通常对架空地线进行改造加装带间隙的绝缘子并采用直流融冰,其融冰电压受到地线绝缘子放电电压的制约,进而也影响了地线融冰的长度。对耐张型和悬垂型两种地线绝缘子在严重覆冰条件下并联间隙大小与地线绝缘子直流冰闪电压间的关系进行了试验研究。结果表明:两种地线绝缘子表面清洁、未覆冰情况下,其直流50%放电电压U50%与并联间距d呈幂指数关系,随着并联间距d增大,U50%增大,且增速逐渐减小;覆冰条件下,耐张型并联间隙地线复合绝缘子并联间距的选择与覆冰厚度di相关,可以选为(10+2di)mm;悬垂型地线绝缘子在严重覆冰地区建议选择80~100mm的并联间距。在保证融冰期间地线与杆塔保持良好绝缘的条件下,应选择较小间距来提高其防雷性能。

DC Icing Flashover Performance of Composite Insulators with a Parallel Air Gap Used for Overhead Ground Wire Insulation

The de-icing method of overhead ground wire has become an urgent problem. An insulator with a parallel air gap is generally installed for overhead ground wire insulation, whose de-icing voltage is related with the flashover voltage of insulator and breakdown voltage of air gap. Thus the air gap affects the de-icing length of the ground wire. Quantitative contrast experiments were carried out to study the relationship between the icing flashover voltages of the insulators and their air gaps. The test results show that, for clean (non-iced) strain and suspension insulators, the relationship between the 50% flashover voltage U50% and the air gap length d can be described as a power-law function. That is, U50% increases with the increase of d, but the growth rate decreases. Under icing condition, the air gap length of strain insulators can be chosen based on the ice thickness di, as (10+2di) mm. In heavy icing areas, the parallel air gap length of suspension insulators can be 80~100mm. During the de-icing period, the air gap length should be chosen as small as possible to improve its lighting protection performance, under the guarantee of good insulation between the ground wire and the tower.