Dear Experts ,

yesterday i have tested a solo run motor with high vibration after overhaul at work shop .

POLE : 2      ,Motor R.P.M : 2910   ,  Hz : 50 , 15 K.W ,   415 V  ,   29.0 Amps . 

N.D.E Bearing : 6309          D.E Bearing : 6310  SPECTRUM ZOOM

Stator slots : 24     Rotor Bars : Not known .

Below i have attached Velocity , acceleration & Displacement spectrum .Please share your Findings .

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Original Post
Kishore kumar posted:

Yes , yesterday balancing done on assembled motor .vibration reduced to 1.5 mm\sec .But I am concerning about high frequency peaks observed and side banda at line frequency or 1x .what will be the motor behaviour ,if it is installed on site to its equipment..

Can you post data showing these peaks, sidebands, etc. after the rework that brought the motor down to 1.5 mm/sec?

"But I am concerning about high frequency peaks observed and side banda at line frequency or 1x."

It isn't clear if that last data is still from a solo test or coupled to a load.  If it is loaded, the various small peaks seem to be about 0.15 mm/sec RMS or lower so I would not be overly concerned.  If the data is solo, then I would proceed with loading the motor up while making observations.   

If the motor is running uncouple to the driven machine, I would be a little concerned with the 9 rpm slip on an uncoupled motor, that is if the spectrum's cursor is displaying the correct 1x rpm.

Sometimes, if the "Locate Peak" function is used to locate a frequency, it can give a, somewhat, wrong frequency, depending on the resolution and the amount of energy "riding" next to the frequency in question, in this case, 1x rpm. The use of the "toggle cursor" function to help align the fundamental and the harmonics of the fundamental, IMO, gives, most of the time, a closer true rpm. But then again, the resolution has an effect on this also.

I am referring to the CSI (Emerson) software. No problem with the software, IMO, just possibly the resolution used.

Have you strobe or confirmed the speed in the data you are posting?

Only my opinion and I could be totally wrong.

Thanks and Have a Great Day,

Ralph

Motor tested solo in workshop before and after corrections .Motor rotor balanced before on dynamic balancing bed , but found vibration after assembly trial run .

Then balanced after assembly again , vibration lowered but found same peaks.

What if it was unbalanced due to electrical issue (electromagnetical forced due to faults in stator or rotor )and then arrested by balancing .

Kishore kumar posted:

Motor tested solo in workshop before and after corrections .Motor rotor balanced before on dynamic balancing bed , but found vibration after assembly trial run .

Then balanced after assembly again , vibration lowered but found same peaks.

What if it was unbalanced due to electrical issue (electromagnetical forced due to faults in stator or rotor )and then arrested by balancing .

The data you posted after a rebalance doesn't show any issues but as Barry pointed out a solo run on a motor leaves a lot to be desired.  The points you bring out, what I've changed to bold text, need load to make potential issues evident.

 

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