Practical Solutions to Machinery and Maintenance Vibration Problems
Chapter 15, Improvement Routines
Section 2, Reworked And New Motors
1. At the electric shop, place motor on gasket material (under each foot) or on a rubber mat.
2. Fiberglass tape the half key in place. Be sure to use key length equal that used when balancing the armature (see section "Key Length Considerations.")
3. Run motor, recording all vibration readings including phase. If acceptable, give copy to Maintenance Department for comparison with vibration levels of total machine. Keep file for the Electrical Department. For some plants, overall, non-filtered vibration readings will be all that is possible with the available instrument. However, a valuable improvement is to obtain FFT spectra.
4. Install motor at the job site, including alignment elimination of soft feet, etc.
5. Run motor and driven machine. Obtain amplitude readings at all bearings. If any one bearing shows excessive vibration, perform a Foot-Related Resonance test.
6. If vibration is still not acceptable, consider those situations whereby the vibration amplitudes increase only when under load, such as vibration due to eccentric air gap, eccentric armature, loose windups or laminations, cracked rotorbars, hot spots and so on.
This textbook contains only part of the information in our Practical Solutions seminar.