A delta connected motor in the following link: http://www.vanbodegraven.nl/en/products/ac-motors/asea-mbg-200-m-60-6/

has rated current 47A, voltage 380V

Here is the rated values. Cos(fi) = 0.8 on the label.

So the power I calculate is = sqrt(3)*380*47*cos(fi) = 24747 is around 25kw

But AS YOU SEE the label stated rated power 22kw

Why my calculation does not match the rated power?


1 Answer 1


The rated power of a motor is the mechanical output power. That is, speed × torque.

The input power to a motor is the electrical input power. That is, line-line voltage × current × √3.

The motor is not 100% efficient. Some energy is lost in the conversion between electrical power and mechanical power.

Your 'missing' 3kW represents the motor's losses, including copper (resistive) loss, iron loss, friction, drag, spinning the integrated cooling fan (if any), etc.


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