Motor making loud noise, but no obvious mechanical/electrical issues.

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GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
Thanks. This motor's is 890RPM. (which is kinda odd, I would assume it's a 8-pole machine, then rpm 900). I will have to verify when exact and at where this vibration was taken.
it's common to put the full load speed on the nameplate ... 10 RPM slip is pretty good. So we'd be looking at multiples of 0.89 to 0.90 kCPM ... I don't know the accuracy of the markers, but the 13.89, if a little off, COULD be a 15x or 16x motor speed. That conceivably could be a ball or roller bearing. Does this motor have plain or antifriction bearings?
You said you've done enough to know what the lamination vibration characteristics would be, so could you share some light on that?
You misread ... I said I've **NOT** done enough to ...

sorry.
 

Besoeker

Senior Member
Location
UK
How did you come to see that 1.774 is quite close to half supply frequency (30Hz)?

If kCPM kilocycles per minute then 1,774 kCPM is 1774 cycles per minute (1000 *1.774) amd the 1774/60 gives you 29.57 cycles per second which is 29.57Hz.
 
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