Are these diesel generator vibration levels normal ?

[edison123]

Equipment: 415 V, 1320 KVA, 50 Hz, 1500 RPM Diesel Generator

Vibration Readings at 1500 RPM on the generator stator frame.:

NO LOAD, EXCITED (Pk to Pk Microns / Peak mm/sec)
D E --------------------------------- ODE
Horizontal - 48 / 10 – 11 ----------- 56 / 11
Vertical - 120 / 15 ---------------- 180 / 18
Axial - 260 / 26 ------------------- 280 / 25

900 AMPS LOAD (Pk to Pk Microns / Peak mm/sec)
D E --------------------------------- ODE
Horizontal - 80 / 15 ---------------- 72 / 12
Vertical - 220 / 21 ---------------- 180 / 17
Axial - 320 / 30 ------------------- 320 / 32

Are these vibration levels normal for a Diesel Engine Generator ? If they are high, what could be the causes ?

Thanks.

* I would go green if only I were not yellow *

 

[sms]

If this was on the engine, I would say it is high but not too high. On the generator, I would consider this way too high, unless this is a mobile unit, or if it is not well supported.

There are hundreds of causes... Can you tell us what the major vibration frequencies are? How is the gen set supported? What is the application (offshore, hospital, nuke plant)? Where exactly are the measurements gathered? You say on the stator frame, but is on or near a bearing?

"Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change?" Oddball, "Kelly's Heros" 1970

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[GregLocock]

Can you post a spectrum?

Cheers

Greg Locock

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[edison123]

Thanks Guys. Will post a spectrum as soon as I get it.

* I would go green if only I were not yellow *

 

[rob768]

NEN-ISO 8528-9 (generators driven by combustion engines) states a maximum vibration level of 25 mm/s RMS for generators at 1500 rpm, in the power range of 100-200 kW, above 200 kW, the limit is 20 mm/s RMS.
Note that in this case the allowed vibration on a generator are governed by the vibrations coming from the engine. For a stand-alone generator, much lower values apply (± 5 mm/s or abouts).
So, in your case, the values are high but certainly not excessice. It is striking that the axial values are highest.
A high level of torsional vibration may cause axial movements in certain type elastic couplings.
May be worth looking into.

 

[matsorensen]

Hello
I see here are professional stuff.
Could you advice me something ...

I have small current generator ( about 5 Horse power) the maximum rotation speed is up to 4000 RPM.
Could you advice parameters of accelerometer which I should use to measure my engine ?
I can expect even 100G that's (mean ~1000m/s^2 --quite huge value) How do determine frequency of sampling for such small engine? ( according Nuiquist I should establish minimum double frequency of that expected on engine)
Could you advice me any other books, or useful PDF-s for this vibro-testing combustion engines ? (besides of that suggested in this group FAQ )
Best regards
Mat