Induction motor condition monitoring: Vibration analysis technique - A practical implementation

Vibration analysis is one of the most successful techniques used for condition monitoring of rotating machines. The aim of this presentation is to show that vibration analysis is a very efficient and convenient tool for diagnosing mechanical and electromagnetic problems in induction motors. This presentation is based on thirty-five years of the author´s experience in the field of vibration motor diagnostics. Case histories from VSC´s field service files covering assorted industries represent typical mechanical and electromagnetic problems found in motors by using vibration analysis techniques. Among them are: bearing failure, mechanical imbalance, structural resonance and foundation problems, winding damage, voltage waveform distortion, faulty control of Variable Frequency Drives (VFD), and combinations of mechanical and electrical problems. A short theoretical analysis of electromagnetic excitation forces based on classical electrical machinery theory is presented. A comparison of the advantages and disadvantages of the varied modern techniques used or recommended in today´s industry for electrical motor condition monitoring is provided. The place of vibration analysis in the realm of expert systems for motor condition monitoring is also discussed.