2009 ECCE — predictive maintenance techniques to determine dirt in railway traction motors using radial stray flux analysis

Advanced maintenance techniques avoid unnecessary operations on equipment, anticipating failures and reducing maintenance operation times. The application of predictive techniques also makes it possible to monitor and supervise critical systems without needing to interrupt their use and to apply individual preventive or corrective measures for each piece of machinery according to its condition. Traction motors are critical elements in railway vehicles, it also being necessary to bear in mind the special working conditions to which they are subjected in the case of underground railway operations. One peculiarity of the environment in which electric railway motors work is that practically the whole network is underground, with a great amount of dirt existing. This dirt, which contains a high concentration of ferromagnetic particles, gets inside the traction motors through the ventilation grilles and accumulates in the air gap in the machinery. This contamination influences stator winding insulation features, since it is highly abrasive and conducts electricity. This work presents a new predictive maintenance method based in leakage flux for diagnosing the level of dirt in railway motors, taking advantage of the ferromagnetic features of this dirt without any need for disconnecting operations, only planning preventive maintenance operations when they are really necessary.