Air Handler Unit High Fan Free End Vibration

Air Handler Unit Vibration Issue 

The vibration readings on the fan free end of the Air Handler AH-15050 have been significantly higher than the baseline during the last 20 days. RMS Acceleration has increased by 100%

Raised noise floor in acceleration spectrum for Fan Free End. The spectrum peaks indicates a VFD speed change from 26Hz to 30Hz(gradually). Due to this change we are observing an increase in Accel RMS vibration. Currently the speed of the Motor is 28Hz.

In the velocity spectrum on the Fan Free End there are sub synchronous peaks present which were not significant before the increase in vibration trend. 

We are seeing 1x harmonics on the fan drive end

Any advise on what could be the problem....

Original Post

If you could give us a little more information, there might be some suggestions. But the data, IMO, which you have provided  is not telling us much.

Where in the frequency range is the acceleration increase located?

Have you some spectrums and waveforms you can post?

Is it a belt drive or a direct coupled drive?

100% above baseline? What is the baseline? Is the baseline based on the overall value in acceleration?

High floor in accel might mean a bearing fault, depending on where the energy is located in Fmax plot.

Sub harmonics could mean bearing cage faults, internal looseness, belt frequency, etc.

Can you give us some more info?

Where in the frequency range is the acceleration increase located?

Frequency range of Accel Peaks are from 1KHz to 1.6KHz

Is it a belt drive or a direct coupled drive?

Belt Drive

100% above baseline? What is the baseline? Is the baseline based on the overall value in acceleration?

Baseline is in RMS accel in radial direction

 

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