synchronous motor model in SKM - how to create one? 1

[CezarM]

Hi,
I will have to produce a TMS report in SKM. In order to do it I have to gather all needed information. The Models in the library seems to be appropriate for asynchronous motors. Or, at least, to synchronous motors only for transient periods (when the equivalent circuit of a synchronous is similar to a asynchronous equivalent circuit). How can I model the steady-state and starting equivalent circuits?

Thanks for help!

CezarM

PS: English is not my first spoken language...

 

[jraef]

CezarM,
TMS is a Transient Motor Starting analysis. A synchronous motor starts as an induction motor anyway, so for modeling it's starting effect on the syupply, I just treated it as such.


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[CezarM]

Jraef, thanks! Would you rather use the equivalent circuit parameters to model, or the performances curves?
I guess the last option might avoid any mistake due to transformation or report to the stator.

 

[jraef]

I always used the performance curves if I had them. A lot of what I did with SKM however was predicting start times under various conditions where the motor and/or system was often not even selected yet, so I had to use the built-in equivalent circuit data. It always ended up so close that I never had a situation where it failed to act as predicted. I may have ended up too conservative, but I'll never know because success for me was in not having a failure to start.

Good luck.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[CezarM]

Meantime, I did a TMS for a asynchronous motor (1500hp, 4160V). As I had no load profile, I made up one linear (as for a fan) only to see the differences between the equivalent circuit model and graphical model.

Quite a difference: the one using the graphical model starts faster (2.5sec) than the equivalent circuit (5.5sec)!!!

And I had all info from motor supplier, just ready to enter in SKM models library.

I attach the PDFs of the resulted curves. Maybe there is an explanation you might find. I give also an XLS file with all data to build the models.

Thanks,
CezarM

PS: the synchronous motor will come later...