SF Induction Motor

Hello nitin_electro

You forgot to say "please"., but here's your answer, located via Mr. Google's fine Search Engine: Results 1 - 10 of about 140,000 for S.F. induction motor. (0.23 seconds)

I selected the Webpage: http://www.eng-tips.com/viewthread.cfm?qid=161272&page=1

<"....Service Factor (SF) is a concept uniquie to NEMA design motors and is defined as a percentage by which the motor can withstand an increased load while still maintaining rated torque and speed within an accepted tolerance, even though current is expected to rise. Some believe this to be a short time rating, however you will never find an AMOUNT of time discussed, mostly because it is nebulous. What is said is that when using a motor's SF, an increased temperature rise is to be expected and therefore the motor life will not be the same as if the SF was not used. Many OEMs choose to use SF as if it represented an increased HP at the shaft, mostly in order to avoid stepping up to the next size motor if their application calls for just a little more than a standard motor design allows. Those OEMs are generally not concerned that the motor will last 5 years instead of 20 years, because either way it is out of their warranty by the time it fails.

the reason why you don't see SF listed for 50Hz motors is because IEC, the governing rules for the rest of the world, make no such claim of a motor being rated for anything other than what it says it is. So in effect, all IEC motors are 1.0SF.....">

So there you are....If you knew how to use an Internet search Engine, you could have located the answer yourself, within a second, just like I did for you.

Trust you feel assisted

Kind Regards....

Any formula u can give me calculate of SF?

Hello again, Guest.

If you read the above Post, with the explanation in italicised lettering, you may understand that there is not a proper formula, because the S.F. rating is nebulous.

Nebulous = Not accurate, just an idea.....

Kind Regards....