发电机定子线棒层间垫条缺陷引起的绝缘击穿分析  

Analysis of Insulation Breakdown Caused by Interlayer Strip Defect of Generator Stator Bar

作　　者：潘剑南 李浩良 PAN Jiannan;LI Haoliang(Guangzhou Yueneng Power Technology Development Co.,Ltd.,Guangzhou 510075,China)

机构地区：[1]广州粤能电力科技开发有限公司,广州510075

出　　处：《大电机技术》2022年第6期43-47,54,共6页Large Electric Machine and Hydraulic Turbine

摘　　要：针对某空冷型燃气轮发电机定子绕组在交流耐压试验过程中绝缘击穿的问题,发现均为上层线棒层间垫条侧的窄面绝缘击穿。通过测量槽楔的松紧度和层间半导体垫条的厚度,以及观察线棒表面绝缘的情况,推断出线棒绝缘击穿的最初原因是层间搭接式垫条接头厚度偏薄。层间垫条缺陷导致上层线棒与层间垫条之间形成空气间隙,并造成中间的槽楔松动。发电机运行时,线棒径向振动较大,造成线棒发生电腐蚀和振动磨损。线棒绝缘在两者的共同作用下不断劣化,最终在交流耐压试验中击穿。最后提出用整条式长垫条代替搭接式垫条的方法解决垫条接头厚度偏薄的问题,能更有效保护线棒绝缘。In view of the insulation breakdown of an air-cooled stator winding of gas turbine generator during the AC voltage withstand test,it is found that all of them are narrow surface insulation breakdown on the side of interlayer cushion strip of upper winding bar.By measuring the tightness of the groove wedge and the thickness of the interlayer semiconductor strip,and the surface insulation of the winding bar,the initial cause of the insulation breakdown of the stator winding and bar is the thin thickness of the interlayer lap joint.The defective interlayer strip causes an air gap between the upper stator winding and bar and the interlayer strip,and loosening of the middle stator wedge.When the generator runs,the radial vibration of the stator bar is large,resulting in electric corrosion and vibration wear.The insulation of the stator winding and bar is continuously degraded under the combined action of the two,and is finally broken down in the AC voltage withstand test.Finally,the method of using the whole long cushion strip instead of the lap cushion strip is proposed to solve the problem of the thin joint thickness of the interlayer strip,which can more effectively protect the insulation of the stator winding and bar.

关 键 词：定子绕组和线棒 层间半导体垫条 槽楔松动 磨损 振动火花放电 电腐蚀 绝缘击穿 

分 类 号：TM303.4[电气工程—电机]