Medium Voltage Motor Vibration - Where do I Start? A Primer for Early Career Professionals

Petrochemical end users are hiring new graduates to fill in for the retiring workforce. Many universities have shifted the focus of their curriculums to cater to the field of high tech, leaving only a handful of institutions with strong programs in power engineering and subfields such as electric machines, power electronics, and power systems. Addressing skill gaps has become a point of discussion, from break rooms to board rooms. Electric motors form the bulk of prime movers for pumps, compressors, fans and other driven equipment. Proper application of electric motors ensures that a given service will be safe, reliable and efficient. Motor vibration is a critical application consideration. This paper outlines the principles of motor vibration, the electrical, mechanical, and civil reasons for their cause, and how vibration is detected and mitigated. Then, the paper describes factory acceptance testing and the governing standards (such as NEMA MG-1 and American Petroleum Institute (API 541)), and compares them from a vibration limit perspective. Finally, the paper discusses what manufacturing or external methods are effective in reducing vibration, and how rotors are balanced and tested to meet requirements. The goal of the paper is 1) to provide basic concepts and terminology related to medium voltage (MV) motor vibration and 2) to share an end user’s perspective on what matters most during specification, evaluation and installation.