Slewing Ring for Wind Turbines

[Farhad Hosseini]

Hi all,

I am working on the slewing rings used in the pitch system of wind turbines.
We have calculated the tilting moments and axial loads for the following load cases:
- nominal operational condition
- maximum operational condition
- maximum downtime condition
- extreme condition

A service factor of about 2 is also suggested for wind turbine application. My question is: which of the above mentioned tilting moments/axial loads must be multiplied by the service factor? All of them? or only the operational moments/forces?

Thanks

 

[tbuelna]

There is a substantial amount of technical information on wind turbine design available at the US DOE NREL website:

http://www.nrel.gov/wind/publications.html

 

[Farhad Hosseini]

I have read many of NREL documents, but I couldn't find any answer to my simple question. My question is Not only for slewing rings, but also for other types of bearing: should we consider service factors for extreme (static) conditions? You know that extreme load that is used for static analyses is very high by itself (with respect to nominal condition), now consider multiplying it by a service factor!

 

[Tmoose]

If you exceed the basic static load, then the rolling elements are dented, and then they'll be noisy in operation (which will get the vibration monitoring system in a tizzy) , AND the service life may even be shortened.

Some factors, based on operating requirements, are here -

http://www.nsk.com.br/upload/file/NSK_CAT_E1254f_146-147.pdf

 

[tbuelna]

Here is a technical reference that should be helpful:

http://www.nrel.gov/wind/pdfs/42362.pdf