不同水分含量下三元混合式绝缘油浸纸板的介电、工频击穿及产气特性对比研究

Dielectric,AC Breakdown,and Gas Generation Characteristics of Three-element Mixed Insulating Oil-impregnated Pressboard Under Different Moisture Contents

矿物油与天然酯组合而成的混合绝缘油能统筹兼顾矿物油和天然酯的优势和不足,近几年受到国内外学者的广泛关注。以矿物绝缘油浸纸板为参比,对不同水分含量的三元混合式绝缘油浸纸板的介电及工频击穿特性进行分析,同时分析了多次击穿后三元混合式绝缘油-纸复合体系的产气特性。结果表明:三元混合式绝缘油浸纸板具有更高的相对介电常数、介质损耗因数和体积电导率,并随着水分含量的增加而增大;三元混合式绝缘油浸纸板的工频击穿电压高于矿物绝缘油浸纸板,且随着油浸纸板水分含量的增加优势更加显著;绝缘油浸纸板多次工频击穿后,H2和C2H2在三元混合式绝缘油和矿物油中的溶解浓度较其他气体浓度偏高;采用三比值法对三元混合式绝缘油-纸复合体系的产气特性进行分析,发现基于油中溶解气体分析判断矿物绝缘油-纸复合体系故障类型的边界阈值不再适用;三元混合式绝缘油中含有的天然酯是造成两种绝缘油-纸复合体系工频击穿产气特性差异的主要原因。

A mixed insulating oil composed of mineral oil and natural esters can take the advantages and disadvantages of mineral oil and natural ester simultaneously,which has attracted wide attention at home and abroad.In this paper,taking the mineral oil-impregnated pressboard as the reference,the dielectric and AC breakdown characteristics of the three-element mixed insulating oil-impregnated pressboards with different moisture content were analyzed,and the gas generation characteristic of the three-element mixed insulating oil-paper composite system after multiple breakdowns was analyzed.The results show that the three-element mixed insulating oil-impregnated pressboard has higher relative permittivity,dielectric loss factor,and volume conductivity,and increase with the increase of moisture content.The AC breakdown voltage of the three-element mixed insulating oil-impregnated pressboard is higher than that of the mineral insulating oil-impregnated paperboard,and with the increase of moisture content,the increasing advantage is more significant.After multiple breakdown of insulating oil-impregnated pressboard,the solubility concentration of H2 and C2H2 in three-element mixed insulating oil and mineral oil are higher than that of other gases.The gas generation characteristic of the three-element insulating oil-paper composite system was analyzed by three ratio method,it is found that the boundary threshold for judging the fault type of mineral insulating oil-paper composite system based on the analysis of dissolved gas in oil is no longer applicable.The natural esters in three-element mixed insulating oil is the main cause for the difference of AC breakdown and gas generation characteristics between two insulating oil-impregnated pressboard composite systems.