环氧-云母复合绝缘固化过程介电响应特性

The dielectric response characteristics of curing process in Epoxy-Mica composite insulation

为研究环氧-云母复合绝缘固化工艺条件对大型发电机绝缘质量影响的机理,采用频域谱法对电机线棒试品进行宽频介电谱测试。根据介电响应理论推导出介质损耗因数随频率和温度变化的关系式,同时实验研究了不同固化温度、固化时间下的介电参数频域特性。结果表明,170℃完全固化后的绝缘体系的介电响应特性要优于150℃和160℃时未达到完全固化的绝缘体系,固化后绝缘体系中小分子交联聚合成大分子,使能发生固化的极性分子大大减少,整体损耗也小于150℃和160℃下的损耗,且完全固化后的试样中各频率对应的损耗散点图也明显有一个收敛的趋势。研究表明,随着固化程度的增加,介质中容易发生转向极化的小分子逐渐减少,使同等频率下的松弛损耗相对于未固化时的损耗大幅度减小,固化后环氧-云母复合绝缘体系的介电性能有大幅度提高。

For studying the effects of epoxy-mica curing process on the quality of high-capacity generator insulation,the frequency domain spectroscopy was used for wide frequency dielectric spectroscopy measurements of the generator bars.The expressions related to the relationship of dielectric dissipation factor with frequency and temperature were derived according to dielectric response theory,meanwhile,frequency domain characteristics of dielectric parameters were investigated under the test conditions of different curing temperature and duration.It is shown that the dielectric response characteristics of insulation system fully cured in 170 ℃ are superior to that of incompletely cured insulation system in 150 ℃ and 160 ℃.Small molecules crosslink into macromolecules after cured,which greatly reduce the curable polar molecules.Total loss is less than those with temperature of 150 ℃ and 160 ℃.In addition,there is a significant convergence trend in the loss scatter plot for each frequency of completely cured samples.It is concluded that,with increasing degree of curing,small molecules prone to orientated polarization gradually reduce,and the dielectric loss thus decrease significantly with respect to the incompletely cured samples in the same frequency.The dielectric properties of epoxy-mica composite insulation is greatly improved after curing.