基于热重和红外光谱分析研究大电机定子绝缘中环氧的老化过程

Degradation Behaviour of Epoxy in Stator Insulation Based on Thermogravimetry and Infra-red Spectrometry

研究了绝缘常用材料环氧在大电机运行应力作用下的老化过程。对运行了23年的和备用的定子线棒主绝缘进行了热重和红外光谱分析。结果表明老化绝缘的热失重增加或增加了两个失重区,红外光谱分析表明C=O和—OH吸收峰强度明显增强,—CH3和—CH2吸收峰强度明显减弱,C—C吸收峰强度减弱。探讨长期承受运行应力作用的定子绝缘中环氧的老化机理为主链断裂、支链氧化。

The degradation behavior of epoxy in stator insulation under operating stresses was investigated by thermogravimetry and infra-red spectrometry. The insulation specimens were cut from a standby and an aged stator bat in a 300 MW/18 kV generator operating for 23 years. It is found that the weight loss measured by thermogravitary on some aged insulation increases, and addition two reaction intervals present in TG or DTG curve of other aged insulation. Based on infra-red spectrum of aged insulation it is found that the absorption peaks due to C=O and --OH increase obviously, those due to -CH3 and -CH2 decrease significantly, and that due to C-C decreases in intensity. The aging mechanism of epoxy in stator insulation under operating stresses for a long term might be the rupture of fundamental chain and the oxidation of branched chain.