牵引电机在线运行达到检修规程规定的运行里程后，应进行高级检修。在高级检修时，对转子转轴进行磁粉检测过程中，在转轴的某特定部位多次发现磁痕显示。分析并判定这些磁痕显示的性质，即是相关显示（疲劳裂纹），还是非相关显示、伪显示等，以为确定转轴是否报废以及牵引电机的在线运行评估提供重要的依据。

When the on-line operation of a traction motor reaches its mileage stipulated in the maintenance rules, advanced maintenance should be carried out. In the process of high-grade overhaul and magnetic particle detection of rotor rotating shaft, it is found many times that magnetic traces appear in a certain part of the rotating shaft. It is of great significance to analyze and determine whether the magnetic trace is related display (fatigue crack) or non-related display, pseudo-display, etc, so as to determine whether the shaft is scrapped and provide an important basis for the on-line operation evaluation of the traction motor.