An electrical machine, its support structure and the load to which it is coupled, form a complex electromechanical system. It can receive impulsive excitations that vibrates it at its own natural frequency, or it can be forced, by the exciting air -gap electromagnetic fi eld or torque spectrum of the driven or driving machine, at many different frequencies. These frequencies may cause the machine to emit an unacceptably high level of acoustic noise, or cause progressive mechanical damage, due to high cycle fatigue, which ends in a machine failure mode.

Chapter Contents:

• 8.1 Introduction
• 8.2 Stator core response
• 8.2.1 General
• 8.2.2 Calculation of natural modes
• 8.2.3 Stator electromagnetic force wave
• 8.3 Stator end winding response
• 8.4 Rotor response
• 8.4.1 Transverse response
• 8.4.1.1 Rigid rotors
• 8.4.1.2 Flexible rotors
• 8.4.2 Torsional response
• 8.5 Bearing response
• 8.5.1 General
• 8.5.2 Rolling element bearings
• 8.5.3 Sleeve bearings
• 8.6 Monitoring techniques
• 8.6.1 Overall level monitoring
• 8.6.2 Frequency spectrum monitoring
• 8.6.3 Faults detectable from the stator force wave
• 8.6.4 Torsional oscillation monitoring (IAS)
• 8.6.5 Shock pulse monitoring
• 8.7 Conclusions

Inspec keywords: fatigue; condition monitoring; vibrations; turbomachinery

Other keywords: electromechanical system; driving machine; electrical machine; exciting air -gap electromagnetic field; natural frequency; high cycle fatigue; support structure; online vibration monitoring; torque spectrum; machine failure mode; progressive mechanical damage

Subjects: Inspection and quality control; Mechanical machinery; Fracture mechanics and hardness (mechanical engineering); Maintenance and reliability; Vibrations and shock waves (mechanical engineering)