guys,
anyone knows vibration data from adre for windows of bently nevada?
kindly look at my data plots attached. data taken from old turbine-generator with overhung exciter rotor. Rated speed at 3,600 rpm.
Any suggestion/analysis?
pls help. need to conduct balancing at all planes?

thanks in advance for any help.

ianski

Vibration_Data_Plots.doc (155 Kb, 131 downloads)

Is the machine online and running? What does the vibration level do when the machine has heated up and is under load? What do the orbits look like under full speed full load conditions? Based on the polar plots and the full spectrums it appears that there is a lot of preload during the startup, and perhaps some rubbing. Do you have any coast down data? While 100 to 150 microns is not great for this class of machine, it is not time to panic either. Make sure you do a complete and detailed analysis. Based on the evidence of preloading, make sure and run the machine at full load for 24 hours or so prior to deciding to balance, and then use the hot coast down data for your balance decisions rather than this startup data. If the orbits remain preloaded at full speed and full load, you may consider an alignment check rather than jumping into balancing. Even if you still need to balance a good alignment will make balancing a whole lot easier.

steve,

this same machine was taken into service last may but again the unit tripped due to high vibration.
pls. see post on critical speed at page#1(post on Vib and Align.)
Note that polar plot was different.

thanks for the reply.

How are you bringing up this machine? It may be that all you need is to do a proper heat soak prior to running up through the critical. Try starting slower, and spending a bit of time (15-30 minutes) soaking every 500 rpm. Also, check to make sure that the slides and guides on the turbine case and support feet are lubricated and free to move as the turbine grows thermally.

Your 1X response has non-linear characteristics on bearings 1 and 2, particularly. Look a the jump between 1900 and 1920 rpm on bearing 2. Looking further, bearing 4 doesn't look all that normal.

I would suggest that this looks like a rub, bases solely on the polar plots. The full spectra shows some odd initiation of 2X also.

Steve mentioned orbits. It would be good to review them also.

Bearing 2 horizontal from 1920 to speed is not the way a polar plot should look for a linear system. Be careful trying to balance. Calculated influence coefficient may be garbage.

Dear iannski,

can I have your e-mail ID please...

Regards,

Madhusudan
India

To steve/william/madhusudan

We have check the foundation bolts for looseness and we have retightened 62 bolts. this is in between the turbine casing and the condenser (at the expansion bellows), also we noticed a crack at the foundation (longitudinal) and applied epoxy for grouting.but the extent of how it damaged the whole foundation still undetermined. We realigned the unit to its OEM tolerance. still the unit tripped at 1980 rpm during start-up. with regards to ramp -up rate and heak soak and orbit plots. ill send it to you thru email. Can i send adre files? so you can have complete data to browse..

Guys thanks.

bayanibiares@yahoo.com

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

Sure, I would be very interested to see some of the ADRE data files.....