Introduction
This case study presents journal bearing fault detection performed on a 2640 kW motor. The motor experienced a significant increase in vibration levels only three weeks after commissioning. Vibration analysis was performed, and the MCM1 AI-assisted diagnostics indicated two potential issues: a journal-bearing fault and a bent shaft. However, the stator current analysis did not show any abnormalities associated with these faults.
Vibration measurement using MCM1 device
Vibration Observations
Measurements showed that the overall RMS vibration was 2.4 mm/s, a value higher than expected. The frequency response revealed a dominant 2X rotational component and a clearly noticeable 4X component, both appearing in no-load conditions.
When the motor is assumed to be properly mounted on its foundation, the presence of these harmonics strongly suggests internal mechanical issues rather than installation-related problems.
FFT Waveform of the Velocity Signal.
Findings
The coexistence of strong 2X and 4X vibration components under no-load operation is characteristic of journal-bearing fault, resulted in a bent shaft.
No signs of mass unbalance, stator winding faults, rotor-bar defects, or electrical anomalies were observed in either the vibration data or the current spectrum. Therefore, the abnormalities are mechanical and internal to the rotor–journal assembly.
Related Frequency Components of Journal Bearing Fault.
Heart Shape Orbit Pattern.
Conclusion
The vibration analysis conclusively identified a critical mechanical condition for the 2640 kW motor. Strong fault signatures—particularly dominant 2X vibration and heart shape orbit pattern—validated the presence of journal bearing degradation. Based on the fault severity, immediate shutdown and corrective action are recommended to prevent further deterioration and avoid potential catastrophic failure.
