This may be a vague description of the motor but it is a 5500hp frame that runs at 7000 hp, used with VFD AC for Z-mill winder. Bearing is 23052CC. What levels should you expect to see on a newly rebuilt unit tested in the shop. I thought .05 in/s pk would be a good alarm limit. They are reporting .12 in/s pk overall. SPectra shows some 1-2-3-4-5-6 x harms. Also a single spike at outer race. Any thoughts?

This message has been edited. Last edited by: jbalko,

You probably already know that NEMA MG-1 specifies 0.12 ips pk/0 overall limit for rigid mounted new motors. EASA AR-100 uses the same limits for motor refurbishments. Most customers have a spec.

As far as what you are seeing... beats me. The harmonics make me wonder about looseness. If motor is running in an unusual configuration such as uncoupled, I always wonder about the preload of the bearings.

If you have single BPFO fundamental with no harmonics, it brings to mind a housing problem. Maybe pillow block bearing not assembled correctly.

We don't have any rolling bearing motors that big. All of our horizontal motors above NEMA frame have sleeve bearings. I haven't run accross that style bearing either. What is it?

Jbalko,
How is the motor anchored down when it is being ran?
Is it just sitting on the concrete, hoping the weight of the rascal will hold it solid.
I have seen harmonics on 300-500 HP sitting on the floor without hold downs, even with excellent balance. Soft foot also when all four feet were mounted down to rails embedded in the floor (rails were old, seen a lot of motors).
Might be sitting on the GM standard rubber matting also (bet it's a high durometer if so).

Dave

JBALKO,
My thoughts are inline with Dave's. I have gone out to our shop to check motors that the mechanic's claim to have " high vibration" only to find that they never bolted it down.
What was done to the motor in shop? What sort of failure did it have? Any machine work?
What does the twf look like? To answer your question: If,on a newly rebuilt motor, I see an amplitude of >.07in/sec, I will redflag the unit
and not allow it to be shipped without another complete check on repairs that were performed on that unit.
Thanks, Jeff

This message has been edited. Last edited by: <Jeff3>,

Note the levels are in RMS. 11.2 equals outer race for the bearing. The bearings had problems and were replaced. Speed is 1198. I am not sure if it was bolted down. I will find out.

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