Power Factor and Calc Current on Motor
Power Factor and Calc Current on Motor
(OP)
When I am calculating the current a motor is going to use for a three phase load what power factor should I use?
The power factor from the manufacturer of the motor or the power factor of the system the motor is connected to?
Formula i am using:
A= (HP*746)/(V*sqrt(3)*PF*Eff)
Thanks
The power factor from the manufacturer of the motor or the power factor of the system the motor is connected to?
Formula i am using:
A= (HP*746)/(V*sqrt(3)*PF*Eff)
Thanks





RE: Power Factor and Calc Current on Motor
But to answer your question, use the motor power factor. The system power factor is a weighted average of the power factor of all connected loads.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Power Factor and Calc Current on Motor
It'll get you in the ballpark.
old field guy
RE: Power Factor and Calc Current on Motor
The power factor of a three phase motor can be as low as 0.6 and as high as 0.92.
Larger motors tend to have higher power factors, slower motors tend to have lower power factors.
The only correct way is to use the actual motor data in which case you would use the nameplate current rating.
Best regards,
Mark Empson
L M Photonics Ltd
RE: Power Factor and Calc Current on Motor
We're also assuming this is an induction machine; if it's synchronous then the full load PF could be anywhere from about 0.8 leading to about 0.9 lagging.
----------------------------------
If we learn from our mistakes I'm getting a great education!