Vibration Analysis and Troubleshooting of Large Synchronous Motors and Generators: Common Faults and Solutions

Despite the generally safe and reliable dynamic behaviour of synchronous machines, large synchronous motors and generators can experience high vibration due to various mechanical and electrical faults. This paper focuses on mechanical faults such as unbalance, misalignment, mechanical looseness, structural resonance, oil instability (i.e., oil whirl or insufficient oil flow), rubbing, and bearing wear. Vibration can be measured using accelerometers located on the bearing housing or proximity probes for journal bearings. These sensors can serve as protection systems, tripping the machine when high vibration is detected, or provide condition monitoring services and machine diagnostics. This paper presents a list of the most common causes of high vibration in large synchronous motors and generators, including recommendations for checks to diagnose the issue and corrective actions to solve the problem. Industrial examples will also be provided. The findings of this study can help asset managers and maintenance professionals troubleshoot and resolve high vibration issues in large synchronous motors and generators, improving their reliability and extending their lifespan.