载流条件下环氧胶浸纸套管温度分布及绝缘特性

Temperature Distribution and Insulation Characteristics of Epoxy Resin Impregnated Paper Bushing Under Current Carrying Condition

为研究环氧胶浸纸套管内部温度分布及对应的绝缘性能,构建了套管温升与绝缘性能同步测试回路,获得了不同电流下套管芯体温度分布及热点温度对套管绝缘性能的影响规律。结果表明:载流条件下套管油端芯体最大直径处存在由于热量累积导致的局部热点;在与套管绝缘材料接触的热点温度<100℃时,绝缘介质中松弛极化损耗现象明显,tanδ随频率变化曲线存在损耗“峰”和“谷”,曲线随着温度增加向高频方向平移,当热点温度>120℃时,绝缘介质中电导损耗作用突出,tanδ随频率变化曲线在对数坐标系中呈直线下降趋势;热点温度>140℃将损坏套管内部绝缘,恢复常温后tanδ和电容量急剧增加,绝缘电阻大幅下降;当热点温度>200℃时,套管内部将产生大量气体,芯体开裂,tanδ突增而电容量突降。该研究可为套管优化设计、试验及运行状态评估提供参考。

In order to study the internal temperature distribution and the corresponding insulation performance of the epoxy resin impregnated paper bushing,a synchronous test circuit for temperature rise and insulation performance of the bushing core was constructed.And the temperature distribution and effects of the hottest spot temperature on the insulation performance of the bushing under different currents were obtained.The results show that local hot spots may be caused by heat accumulation at the maximum diameter of the core at the bushing oil end under current carrying conditions.When the hot spot temperature in contact with the insulating material of the bushing is lower than 100℃,the phenomenon of relaxation polarization loss is obvious.There are“peak”and“valley”in the tanδ-frequency curves,and the curve shifts to the high frequency direction with the increase of temperature.When the hot spot temperature is higher than 120℃,the conductivity loss is prominent,and the tanδ-frequency curve shows a linear downward trend in the logarithmic coordinate system.If the hot spot temperature exceeds 140℃,the insulation of the bushing will be damaged,which is embodied in tanδand the capacitance increases sharply,and the insulation resistance decreases significantly.In case of severe local overheating with hot spot temperature exceeding 200℃,a large amount of gas will be generated inside the bushing,and the core will crack.And the tanδincrease but the electric capacity decrease suddenly.This study can provide a reference for the optimal design,test and operation state evaluation of the bushing.