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direct coupling alignment

direct coupling alignment

direct coupling alignment

(OP)
Dear Friends

We are going to couple a 1500 HP -4  Pole- sleeve bearing electric motor with one Hellicoidal gear box, is direct coupling, the problem is the process start with in  no load for 30 minutes and later take total  load so is not a continuos duty.

Wich considerations we have to take account for a good alignment including  termal expand and all this? The shaft diameter is 4.5 inches.

Thanks and regards

Carlos       

RE: direct coupling alignment

1500 HP motor and drive? All the precautions you can think of and know. There are professionals who do alignment and vibration analysis for living. Hire them. Follow manufacturers' recommendations, that includes mfrs of the coupling, the motor and the gearbox.

Continuous duty or not has no bearing on the alignment. Type of coupling and gear box may be.

Rafiq Bulsara
http://www.srengineersct.com

RE: direct coupling alignment

In short leave this to mechanical engineers or post in a mechanical forum.

Rafiq Bulsara
http://www.srengineersct.com

RE: direct coupling alignment

It seems like you have 2 choices:
1 – compromise alignment – midway between target corresponding to no-load temperature and target for continuous run temperuatre.
2 – ignore startup and focus on continuous run conditions.

I am inclined toward #2 because I'm guessing the time spend running at load is a lot longer than the 30 minute no-load.
 

=====================================
(2B)+(2B)'  ?

RE: direct coupling alignment

Actually it can take most machinery more than 30 minutes to reach equilibrium anyway. So again that argues for #2.

=====================================
(2B)+(2B)'  ?

RE: direct coupling alignment

At that power level, with a sleeve bearing device involved, direct coupling is just stupid.

How long will it take for the replacements to arrive?

 

Mike Halloran
Pembroke Pines, FL, USA

RE: direct coupling alignment

I'm not sure where you're coming from with that comment Mike.  To me "direct coupled" means that a flexible (or rigid) coupling is used instead of a belt. That seems pretty common to me in sleeve bearing applications.  Using a belt on the other hand would seem stupid to me.  

=====================================
(2B)+(2B)'  ?

RE: direct coupling alignment

What I meant to say was not "stupid".  
But it is not common to use belts with sleeve bearings.   
On the other hand direct coupled is very common with sleeve bearings.  
And a great many of those direct-coupled sleeve bearings machines endure brief periods with less than optimal alignment on the way to thermal equilibrium.  It is not ideal, but we have many that operate that way reliably.  The question can be a matter of degrees (how misaligned)...none of us can answer that without knowing more.   
 

=====================================
(2B)+(2B)'  ?

RE: direct coupling alignment

Pete, I read the OP's use of 'direct coupling' to mean 'rigid coupling'.  

If a proper flexible coupling is used, then there should be no particular concern about alignment changing with warmup, etc.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: direct coupling alignment

(OP)
Thanks for the answers Pete, the problem goes more far of the good alignment, we was made a vibration analisys and we found strange vibration level in the gear box (2X) so we think maybe the problem could be wrong alignment.
I will attach the analisys later to know your comments.

Regards

Carlos  

RE: direct coupling alignment

(OP)
Hello Pete and Friends

The vibration analisys is attached all report is wrotte in Spanish but all data was collected with SKF instrument and the keys are the followings:

Figura 4.1 Global vibration levels in NDE Motor
Figura 4.2 Vibration Spectrum NDE Motor
Figura 4.3 Global Vibration levels DE Motor
Figura 4.4 Vibration Spectrum D.E Motor
Figura 4.5 Global Vibration Level in Gearbox
Figura 4.6 Vibration Spectrum in Gearbox  

NOTE: Gearbox is double helicall, reducer.

Thanks for the inputs

Carlos  

RE: direct coupling alignment

(OP)
The vibration analisys is attached all report is wrotte in Spanish but all data was collected with SKF instrument and the keys are the followings:

Figura 4.1 Global vibration levels in NDE Motor
Figura 4.2 Vibration Spectrum NDE Motor
Figura 4.3 Global Vibration levels DE Motor
Figura 4.4 Vibration Spectrum D.E Motor
Figura 4.5 Global Vibration Level in Gearbox
Figura 4.6 Vibration Spectrum in Gearbox  

NOTE: Gearbox is double helicall, reducer.

Thanks for the inputs

Carlos   

RE: direct coupling alignment

With all those 1X and 2X, it looks to me like a misalignment. How was the motor aligned ? Laser, dial gauges ?

Muthu
www.edison.co.in

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