电力变压器绝缘纸热老化的击穿电压特性

The Breakdown Voltage of Power Transformer Insulation Paper After Thermal Aging

基于对矿物油、植物油分别与热稳定绝缘纸组成的油纸绝缘系统在90℃、110℃、130℃下进行的500多天的加速热老化试验,研究了其击穿电压特性变化规律,并且进一步分析了变化产生的主要原因。试验结果表明:两种油纸组合在三个温度下,击穿电压均有上升的趋势,以110℃和90℃下的样品尤为明显;植物油组合的油纸绝缘击穿电压整体高于矿物油组合的油纸绝缘;击穿电压与老化温度、绝缘纸聚合度之间并无明显关系;在老化过程中,整个油纸绝缘系统并未达到水分平衡,绝缘纸中微水含量基本保持在2%以内,老化过程中的微水对绝缘纸的击穿电压影响不大。

Breakdown voltage is a very important dielectric parameter for dielectric materials.The analysis of breakdown voltage during aging process of transformer insulation paper is of great significance for the mechanism research.Therefore,in this paper,a set of accelerate thermal aging experiments are designed under three different temperatures（90℃、110℃、130℃） and lasted for more than 500 days,and there are two oil-paper insulation systems made up with mineral oil/thermal upgraded insulation paper,and BIOTEMP oil/thermal upgraded insulation paper used in this experiment.The test specimens were sampled periodically and then the breakdown voltages were analyzed.Further more,the main reason of the breakdown value variation was discussed.The test results indicates that,under three different temperatures,the breakdown voltage of insulation paper in both the two insulation systems had the tendency of small increase,especially under 110℃ and 90℃.The breakdown voltage of KR is entirely higher than PR.There are no obviously relations between breakdown voltage and aging temperature,neither with DP of insulation paper.During thermal aging,water in oil-paper insulation is not equilibrium,water inside insulation paper is always below 2% and the affection to breakdown voltage made by water content is very tiny.Thus,to research the whole electric performance of oil-paper insulation in future,more attention should be paid to the overall oil-paper insulation system.