thermal time constant

[giordanonaval]

Hi!
Does anyone know where can I find the thermal time constant of electrical asynchronics motors?
thanks in advance.

Martin

 

[aolalde]

Ask to the motor manufacturer.
That constant will depend on the motor materials, current pattern and cooling system. Could be quite different for different brands.

 

[giordanonaval]

Thanks aolalde!
I know wath you say, but the manufacturer dont want to give that information because it's their "know how".
That's why I was looking for another way to find that information.
Thanks again
Martin

 

[dede61]

Ask the manufacturer for the TAU value, tell him its for protection relay setting. He should give it to you.
This value is different for every manufacturer and model.

regards,

Danny

 

[electricpete]

If you want to do a test, you can do it, just measure temperature vs time after a motor shutdown. Plot it on a log(Temp) vs linear (time) scale and the slope should be:
-1/tau

I had posted some shutdown temperature patterns for motors at our plant a few years ago... might be of use as "typical" values. Unfortunately the search feature at this site does not allow you to combine different criteria such as posts by a specific user containing a specific keyword (pick one or the other... keyword or user). I have too many posts to look through them all.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[davidbeach]

Try using google to search for it. Put in the conditions, which google will let you do, and then add site:eng-tips.com at the end of the search string. I don't know how use of the google button on the eng-tips pages would work compared to using google directly.