Power Factor Correction for a Single, Three Phase Motor
Select horsepower, insert motor efficiency, select motor power factor percentage,
select desired power factor percentage. The required kVAR is then displayed.
Select hp
Insert motor efficiency (Note 4)
Motor power factor % (Note 4)
Desired power factor %
The formula to calculate is: [("A" x 0.746) divided by ("B" divided by 100)] multiplied
by "E" (which is the value from array of "C" and "D") = "F". "G" is the value from the range that "F" falls into which are the
standard sizes of kVAR capacitors.
("C" divided by "D") multiplied by the nameplate FLA = corrected current amps.
Overload current correction for motor used above (Maintain previous values,
insert nameplate FLA and press the calculate button.)
Nameplate FLA
Corrected current
Notes:
If power factor correction is needed on a motor controlled by a variable frequency drive or a soft start, contact the device manufacturer for a solution.
Do not try to overcorrect power factor. This can cause unintended problems that should be avoided.
This calculator rounds down to the lower value for correct capacitor sizing.
Full load power factor and efficiency data on the motor needing correction can be found in product data sheets, on the manufacturer's web site or from the motor's supplier.
