Optimizing Motor Load Power Calculations for Load Flow Analysis

[Physicist3]

Hi,

If you are entering motor load data (Real and Apparent Powers) into a power system analysis software so that a load flow analysis can be conducted and you are calculating these powers based on current and voltages, do you assume and use the full load power factor for the motor, as obviously the motor power factor changes with load so it would be difficult to obtain its exact value for a particular load?

Cheers.

 

[Babadag]

I am not sure how accurate you need a calculation. The actual motor parameters [rated current, torque and other] precision it is +/-15-20% and the efficiency and power factor from 50% to 110% load it is only 5-10%.

 

[FOIWATER]

Power utility contractors that develop load flow software agree to use a power factor of 85% for such loads

I don't have a direct source, but I developed a program such as yours for a project in a power system course, I believe it may have been from etap..

I recall it being custom to use 85%

Even if you are talking about a industrial load where only the real power draw is known it is common to find the reactive power using an 85% power factor assumption