Axial Vibration at Outboard bearing of 1410 kW motor

[Inspectengr]

We have Motor driving Reciprocating compressor with following specifications:
OUtput: 1410 kW
Voltage: 6300
Amps: 170
Phase: 3
Frequency: 50 Hz
Rated Speed: 295 RPM
Speed Monitored: 299 RPM
Stator winding 168 slots wound with a 2-layer lap winding
Rotor WInding: 204 Slots with cage rotor winding
Poles: 20
Sleeve type bearing.

We are experiencing at M1A (Motor outboard axial) peaks at 12x, 14x, 16x - Vibration for last 6 months. and the amplitudes is on rise consistently. Maintenance carried out of bearings area but no abnormality found. Attached please find spectrum of the motor with CSI-2130.
Can any one give the idea what could be the real problem behind these peaks????
Urgent reply awaited.

[machinedoc]

Never seen such spectrum on a reciprocating compressor. Anyhow spectrum indicates some looseness in the system. Can you send me the peakview data captured with your CSi to determine the effect of impacting in the system.

[Inspectengr]

Attached find more data

M1P - Motor outboard peakvue
M1A- Motor outboard axial
M2P- Motor inboard peakvue
C1P- Compressor inboard peakvue
C2P- Compressor outboard peakvue

Hope this clarify the problem...

[machinedoc]

Can you please send me the cross phase data of compressor across coupling

[Inspectengr]

Currently, as soon i get the data i will provide it...
we have to perform tests on the machine tomorrow... what sort of tests should we be focusing to clear ourselves regarding the problem...

[machinedoc]

What sort of test are you planning to?
1. You can change the lube oil pressure and temperature and see its effect.
2. See if you can clean the motor fan.
3. See if you can vary the number of drops of lubricator in the stage.
4. Increase in gas pressure can also be useful.
Usually high axial vibration with sinusoidal noise is due to the change in magnetic center of motor. Do you have abnormal noise also in your case?

If you still have increasing trend in vibration you should take the machine down and inspect piston locknut, rider band, and big end and crankshaft bearings as soon as possible.

[fraz]

Do you have a rod drop system installed at your machine? If not then you should also inspect its rider band

[Inspectengr]

Thanks for ur observations and suggestions.

Good news is that the vibration on the machine have reduced. The maintenace activities carried on the machine are:
1. Sleeve bearing inspection (Found ok)
2. FOundation bolts tightened. (Found slightly loose)

Attach also found vibration data of the point with reduced vibration.
Regards

[machinedoc]

Good to hear this