Compressor Bearing Vibration

[rasmumm]

A Motor that drives our centac air compressor has suddenly increased vibration readings with a dominant peak at 2X which is extremely close to being BSF. It increased over 7 days from .058ips to .142ips. There is a cyclical noise being emmitted from the bearing that I can detect using ultrasonics. My question is, this being a 3600rpm motor, how long do I have before I should replace the bearing?

 

[CRS1]

Is it possible that the 2 X increase is actually at 2 X Line feq. (120 Hz)> If you don't have enough spectral resolution, it can be hard to distinguish on a 2-pole motor. Increased 120 Hz vibration is related to a motor electrical problem of some sort. I have seen a poor electrical connection on one phase create a substantial increase at twice line frequency, and "softfoot" or stator problems could also be causing the increase.

Tim Wechsler

 

[JasonChen]

You said that your compressor has "suddenly" increased vibration readings with a dominant peak at 2X. I suspect your motor of softing foot. You have to check the tightness of feet as well as alignment before replacing the bearing.

Regards,
Jason

 

[tophat]

Hi, In my experience as an analyst over 13 years, I believe your problem is probably eloectrical. One way to check is to cut the power while monitoring the motor to see if the sound and level suddenly quits. You should take some high resolution spectra to see if it is 2X running speed or electrical. Good Luck
Tophat.