Comparison of induction motor bearing diagnostic test results through vibration and stator current measurement

The paper discusses results of tests performed by authors, related to the engine bearings diagnostic using vibration and stator current measurements. Vibration methods for bearing diagnostics have one disadvantage they require the availability of the machine for sensors installation. This is the reason for seeking new methods based on motor supply current analysis. It can be assumed that each bearing defect causes radial movement between the rotor and stator of the machine. These changes generate additional stator current harmonics. The paper contains the description of an automatic measurement system, developed for the measurement of those harmonics and processing that data to obtain bearing diagnostic information. System was tested on objects with intentionally made defects in bearings, results of this test was also shown in the paper.