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1994年初,我们分厂接到修复1万2千kW汽轮发电机励磁机电枢铜环的任务。异常现象是励磁机运行过程中有电火花产生,危及整个发电机组的正常运行发电。 一、问题的分析 电枢的铜环长140,直径为200_0~(+2),公差值很大,尺寸精度要求不高。电刷靠弹簧弹力压紧在电枢铜环表面,实现滑动配合。电枢铜环的表面粗糙度值为R_a0.4。现场检查发现,电枢铜环表面被电刷磨损出数道环形沟痕,深浅不一。最深的沟痕估计达到0.4～0.5。沟痕的产生严重地降低了铜环表面质量。由此可见,沟痕使电刷在电枢铜环表面之间产生了间隙,致使电枢运转过程中产生电火花。 分析结果:铜环尺寸仍在公差范围内,只是表面质量已不能满足正常运行的需要,远远超出了设计要求。去除沟痕,电枢铜环表面恢复设计要求的粗糙度值。直径需缩小0.8～1.0左右,尺寸仍在公差范围内。使用时有弹簧弹力的作用,不会影响运行。因此研究决定:设法恢复铜环表面粗糙度值。
In early 1994, our factory received the task of repairing 12,000 kW turbo-generator armature copper ring. Anomaly is the occurrence of sparks during the operation of the exciter, endangering the normal operation of the entire generating set. First, the analysis of the problem Armature copper ring length 140, diameter 200_0 ~ (+2), the tolerance value is large, the dimensional accuracy is not demanding. The brush is pressed against the surface of the armature copper ring by spring force to achieve a sliding fit. Armature copper ring surface roughness R_a0.4. Site inspection found that the armature copper ring was brushed a few ring groove scratches, shades. The deepest groove marks are estimated to reach 0.4 ~ 0.5. The occurrence of groove marks severely reduces the surface quality of the copper ring. Thus, the groove marks the brush in the armature copper ring between the surface of the gap, resulting in spark armature operation. Analysis results: copper ring size is still within tolerance, but the surface quality can no longer meet the needs of normal operation, far beyond the design requirements. To remove the furrow marks, the surface roughness of the armature is restored to the desired roughness value. Diameter should be reduced by about 0.8 to 1.0, the size is still within the tolerance. Spring elastic when used, will not affect the operation. Therefore, the study decided: try to restore the copper ring surface roughness value.