MacMcMacmac
Aerospace
- Sep 8, 2010
- 56
Good Day. We have a large turbo exhauster here that we are trying to solve a vibration issue on. It will peg the vibration monitoring meter at startup, but gradually level out within acceptable limits after running for an hour or so. We are trying out various theories as to why the vibration has come about after the main driver was overhauled a few months ago after a drive bearing failure (roller type). The vibe meter pegged when the motor bearing began to overheat. I hit the e-stop and it coasted down normally. The motor was overhauled, re-installed, and aligned to within acceptable parameters using a PrufTeknik Rotalign.
What is bothering me is the seemingly absurdly low temperature alarms on this machine. The oil temperature is going into warning at 107F, and will go into alarm at 115F. This seems way too low. Shaft speeds are 1775 input, 4500 output, and 1775 input, 7000 output. 2 motors, 2 exhausters in series.
What bothers me, is that these alarm levels are colder than what we keep the oil warmed up to in the sump of our other 4 machines when standing idle. Offline temperature for these is in the 120F range. Rotor speeds on one of those machines is 39,0000rpm. The alarm temperature on our 5MW compressor, which is from the same manufacture and of similar general design, is 138F, which still seems low to me, but is a bit more reasonable.
My question is, do you think the oil temperature is too low and will this contribute to vibration issues? Is there a rule of thumb as to what an ideal temperature range is for a plain babbitt bearing?
We have a 6MW Cooper-Cameron MSG turbocompressor that would trip out on startup until we upped the resting oil temperature another 10F.
Oil is Shell Tellus 32.
We have virtually no information on the first machine as it was war booty taken from the Nazis. Brown-Boveri circa 1933 or so.
What is bothering me is the seemingly absurdly low temperature alarms on this machine. The oil temperature is going into warning at 107F, and will go into alarm at 115F. This seems way too low. Shaft speeds are 1775 input, 4500 output, and 1775 input, 7000 output. 2 motors, 2 exhausters in series.
What bothers me, is that these alarm levels are colder than what we keep the oil warmed up to in the sump of our other 4 machines when standing idle. Offline temperature for these is in the 120F range. Rotor speeds on one of those machines is 39,0000rpm. The alarm temperature on our 5MW compressor, which is from the same manufacture and of similar general design, is 138F, which still seems low to me, but is a bit more reasonable.
My question is, do you think the oil temperature is too low and will this contribute to vibration issues? Is there a rule of thumb as to what an ideal temperature range is for a plain babbitt bearing?
We have a 6MW Cooper-Cameron MSG turbocompressor that would trip out on startup until we upped the resting oil temperature another 10F.
Oil is Shell Tellus 32.
We have virtually no information on the first machine as it was war booty taken from the Nazis. Brown-Boveri circa 1933 or so.
