Motor Vibration
Motor Vibration
(OP)
We have a horizontal 15,000hp motor driving compressors at each end of the shaft. We get concerned when vibrations approach 0.5 in/sec. We are getting high axial vibrations (up to 1.4 in/sec) at the brush end bearing pedestal at 2x running speed; no other harmonics, and no high readings at the other pedestal. We have checked compressor and coupling alignment and checked for soft foot; no problems there. Motor runs on magnetic center with adequate clearance at thrust bearings. Axial vibrations stop when power is removed and the motor coasts down. MCE test indicates no problems with air gaps or rotor bars. Can anyone suggest where else we can look?
Larry






RE: Motor Vibration
Most common electrical problems occur at 2*Line frequency. Is it possible that this frequency is 2*line frequency instead of 2x running speed?
Alignment was a logical item to check with 2x running speed and high axial vibration…. Might be worth double checking thermal growth compensation et cetera. Also a check of phase might give you some ideas.
RE: Motor Vibration
The problem is always obvious once you see what it is.
Larry
RE: Motor Vibration
thanks.
RE: Motor Vibration
For instance an airgap eccentricity (static) will cause twice line frequency vibration.
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Vibration