大型发电机主绝缘老化的热分析研究

STUDY ON THE AGING OF STATOR INSULATION OF LARGE GENERATORS USING THERMOANALYSIS

大型发电机主绝缘老化与主绝缘内部微观缺陷的产生和发展以及环氧劣化有着极为密切的关系,该文对大型发电机主绝缘进行了热重分析和差示扫描量热分析研究。实验结果表明:与完好部位相比,缺陷部位的环氧含量以及环氧的氧化起始温度明显降低;而且,缺陷部位环氧的裂解活化能 DE显著增大。分析认为,多应力作用下环氧的老化是缺陷得以产生和发展并最终导致大电机主绝缘结构老化的重要原因。

The aging of stator insulation of large generators has great relation with appearance and development of micro defects inside the insulation ,and deterioration of epoxy. In this paper, Thermogravimetry (TG) and Differential Scanning Calorimeter (DSC) analysis are applied to the study on the aging of stator insulation of large generators. The results show that, compared with that of the sound parts, epoxy content and starting oxidation temperature of the defective parts presented much more remarkable changes in its physical and chemical performance. In detail, its content and starting-temperature of oxidation decreased obviously; furthermore, its decomposition-activation energy DE of epoxy in the defective parts increased evidently. It is considered that the aging of epoxy caused by multi-stresses is the main reason for the generation and development of defects and the final aging of the main insulation structure of large generators.