Importance of Bearing Heat Runs 1

[CuriousElectron]

Hello Guys,
I am trying to better understand the importance and the reason why the bearing heat runs are performed when commissioning or testing a generator after a major upgrade/overhaul. Here is what I came up with so far:
1. Confirm the metal temperature rises with increased MW output on the unit.
2. Indirect monitoring of shaft alignmnet. If the generator/rotor shaft was not aligned properly, a hot spot is likely to be developed on the guide bearings.
3. Confirm the effectiveness of the oil cooling system. At higher unit output, the bearing temperaure is maintained at design limit by having operational cooling system to remove heat.

Am I correct in my evaluation? What are some other reasons why heat runs are performed?
Thanks,
EE

 

[electricpete]

I’m more familiar with motors than generators so I'm probably going to miss your question.

For journal bearings, some additional factors may include the clearance in the bearing, the critical geometry of the bearing (radiuses of curvature), the shaft journal finish, alignment between the two bearings of the generator, shaft bow (which can affect shaft/bearing alignment).

These may show up as elevated temperature at no load, but there may be factors associated with loading that affect the ultimate highest bearing temperature. And the customer doesn’t want to be surprised to find them out later.

Sorry if it's not what you were asking, just chimed in with what made sense to me.


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(2B)+(2B)' ?

 

[Jacey Tome]

The ball bearings used in most electric motors are pre-greased, shielded ball bearings. Normal motor bearing operating temperatures range from 140° to 160°F.

https://www.mie-solutions.com/mie-blog/manufacturing-software-systems-reduce-time-material-waste