I have a 3 phase AC induction motor for which I want to calculate the power factor. I have the following nameplate information.

Nominal Power (P2): 2,7 KW
Rated input power (P1): 3,3 KW
Voltage: 400 V
Frequency: 50 Hz
Rated current: 5,4 A

I need the power factor, can I compute this?


1 Answer 1


The power factor at rated load is the rated input power, 3.3 kW divided by the rated input kVA 400 x 5.4 x sqrt(3) / 1000 = 3.741; 3.3 / 3.741 = 0.88 pf. If the motor load is less than rated load, the power factor will be lower. Most motor manufacturers can supply data for 1/4, 1/2, 3/4 and full load.


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