大型汽轮发电机定子主绝缘老化状态的研究

大型发电机运行过程中，在定子线圈的不同部位处，主绝缘会受到不同程度的多种应力作用。为了研究定子线圈不同部位处主绝缘的老化状态，本文对一台已运行了16年的大型汽轮发电机的定子线棒进行诊断试验，包括：极化指数测量、不同电压、温度下的介质损耗测量、交流电流测量、局部放电测量及声学测量。试验结果表明，定子端部主绝缘的老化程度比槽部主绝缘要严重。因此，建议在进行大型发电机预防性维修试验时，应注意端部绝缘的检测与维护。

Aging assessment of stator insulation in a large turbogenerator

Different portions of stator insulation of large generators are subjected to multistresses with different strength during operation. In order to study the aging extent of stator insulation, diagnostic tests are performed on the specimens of stator bars obtained from a large turbogenerator, which has been operated for 16 years. The tests include polarization index test, dielectric loss measurement at various voltages and temperatures, AC current measurement, partial discharge test and acoustic detection. The test results show that the aging extent of groundwall insulation of endwindings is more serious than that of the groundwall insulation in the slots. Based on the results, suggestion could be made that during predictive maintenance testing of large turbogenerators, more attention should be drawn to the insulation of endwindings.