from the Forum department...
Motors Absorbed Power Calculation
Engineering and workplace issues. topic
Posted by Rasa on 27 December, 2008 - 7:12 am
I'm a problem. Our client has made a comment and has requested for absorbed power for 3ph induction motors.

We search net and what I found is as below:
In a site I found:
Absorbed Power=(Rated Power * Load Factor) / Efficency

In another web we found:
Absorbed power = Eff. * (sqr3)*V*I*cos p

But these equations are completely different! In practical, I knew 2nd formula as Rated power equation.
Now, I can't find difference between rated & Absorbed power & rated KVA!!!

I'm very turbulent now!!! please help me. Thanks.

Posted by cappowerman on 28 December, 2008 - 4:57 am
The second equation is correct.This is the rated power of the 3ph induction motors.This is the correct formula for rated power as well as absorbed power where every quantity is measurable. The rated KVA is calculated using the formula as below:-

KVA= Rated or absorbed power/power factor(i.e. cos phi).

Hope this clarifies & dampens your turbulence.

Posted by Sujay Thakur on 16 February, 2012 - 3:53 am
well, the 2nd equation is for finding the rated motor KW (if motor supplier does not provide). Absorbed power is the expected power drawn by the load. Most loads does not operate at its rated capacity, but at lower point. The motor is typically sized so that the rated capacity of the motor exceeds the expected absorbed load by some conservative design margin. and its only Rated load * load factor. That's too supplier responsibility to provide, if not then a load factor between 0.8 to 0.9 is normally applied.

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