表面受潮对浇注干式变压器线圈表面电场的影响研究

Study on the Influence of Face Wetting on Coil Surface Electric Field of Casting Dry-type Transformer

通过对一台10kV环氧树脂浇注干式变压器的外绝缘表面的电场分析来探究其在受潮环境下的放电机理.首先建立了该变压器的二维电场分析的有限元模型,并对其外绝缘表面干燥、带有连续受潮层两种不同运行环境下的沿面电场进行了对比分析,结果表明,相比于表面干燥,当表面带有连续受潮层条件时,变压器外绝缘表面局部电场强度升高近10倍,可能会在外绝缘表面产生沿面放电现象,这对外绝缘造成了一定的威胁.本文采用一种特殊的工艺对该变压器的外绝缘进行表面处理,使得连续的受潮层离散为分离的水滴,并对此情况下的表面电场进行了分析计算,通过与上述带有连续受潮层的计算结果进行对比,局部外绝缘表面电场强度降低80%,有效地提高了环氧树脂浇注干式变压器的寿命.

This paper investigated the discharging mechanism of dry-type transformer by analyzing theoutside insulation surface electric-field distribution of a 10kV epoxy resin cast dry-type transformer. First ly, the 2-D finite element model was established, and on this basis the surface electric-field distributions were analyzed under two operating environments of the dry outside insulation surface and the external in- sulation surface with wetting layer. The results have indicated that the local electric-field density of exter-nal insulation surface rises nearly ten times compared with the dry external surface, which is easy to cause the creeping discharging phenomenon and poses a threat to external insulation. A type of low surface ener gy coatinR was used on the Ufield distribution was analyzed when the coating surface was covered with dispersed water drops. Com pared with the above results, it is obvious that the surface electric-field density decreases eighty percent, which can effectively increase the life of the epoxy resin cast dry-type transformer.