From the attached document I see that you are pushing your limit of 7.1 mm/sec at 80% speed. But beyond that we know very little about your installation.
Can you provide more details; size of motor, RPM, how is motor coupled to fan?
Have you done or observed the fundamental 1st thing often recommended with a motor issue? That is checking what the amplitude does immediately after removing power. If the amplitude "hangs" some during the coastdown, then you likely have a mechanical issue; if it immediately drops, then you likely have an electrical issue.
"No 1x or 2x" at all? Even when the spectrum is shown in Micron units instead of mm/sec RMS and the amplitude scale is not controlled by the highest amplitude peak (3X), which might "squeeze" 1x down so as not be able to actually "see" it (1x) as much of a concern? In other words, can you get a 1x reading in displacement?
Have you been able to do a coastdown plot of the amplitude vs rpm, at the very least, from 80% speed, down to zero speed.
What are the RPMs at each Percentage reading you have shown us?
I just noticed that the original problem statement states “vibration at 45% 50% 60% 70% 75% 80% load” whereas the document refers to percentage of speed. Important that we know what these percentages make reference to, load or speed, otherwise we are just guessing!
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