Motor primer. II

In recent years, much has been written about applying motors with variable speed drives, high speed rigid shaft motors, the impact of API Standard 541 on motors, motor diagnostics and much more. Most of these papers and articles assume that the reader has significant knowledge of motor theory and operation. However, this assumption is overly optimistic, considering that little, if any, colleges teach motor theory today and that application experience at motor user locations has been significantly reduced in recent years. This paper is the second of a series of papers on motor basics. The authors present motor theory and application information with an extensive reference list that will help engineers understand such questions as "why do motors make pulsating noises?". This paper will also serve as a valuable reference for those who use or purchase motors.