What is Motor Power Factor?
Motor power factor (PF) indicates how effectively an AC motor converts the supplied electrical power into useful active power.
It is the ratio of real power (kW) to apparent power (kVA).
Motor Power Factor Formula
For a three phase motor:
Power Factor = kW / kVA
It can also be calculated as:
PF = P / (√3 x V x I)
Where
P - Motor input power in watts
V - Line voltage in volts
I - Line current in amperes
Why is Power Factor Important?
A low motor power factor increases current for the same power output, resulting in higher I²R losses, voltage drop, cable loading, and transformer capacity requirements. Improving the power factor can help reduce electrical losses and improve system efficiency.
How can Motor Power Factor be Improved?
Motor power factor can be improved by operating motors closer to their rated load, selecting appropriately sized motors, and using power factor correction capacitors where suitable. Proper sizing and coordination of capacitors are essential to avoid overcorrection and resonance.