An analytical approach to solving motor vibration problems

Vibration problems in induction motors can be extremely frustrating and may lead to greatly reduced reliability. It is imperative, in all operations and manufacturing processes that downtime is avoided or minimized. If a problem does occur, the source of the problem is quickly identified and corrected. With proper knowledge and diagnostic procedures, it is normally possible to quickly pinpoint the cause of the vibration. All too often, erroneous conclusions are reached as a consequence of not understanding the root cause of the vibration. This may result in trying to fix an incorrectly diagnosed problem, spending a significant amount of time and money in the process. By utilizing the proper data collection and analysis techniques, the true source of the vibration can be discovered. This includes, but is not limited to, the following: electrical imbalance; mechanical unbalance-motor, coupling, or driven equipment; mechanical effects-looseness, rubbing, bearings, etc.; external effects-base, driven equipment, misalignment, etc.; resonance, critical speeds, reed critical, etc. Once the electrical and mechanical interactions in a motor are understood, and the influence external components have on the apparent motor vibration, identification of the offending component is usually straightforward. This paper provides an analytical approach for expeditiously understanding and solving these types of problems.