Power Factor Correction Calculator
Estimate the reactive compensation required to move a load from its existing power factor to a selected target and see the effect on kVA and line current.
Calculation method
The calculator uses P, the existing power factor and the target power factor to determine the reactive-power change. With φ = acos(PF), the required capacitor-bank reactive power is Qc = P × (tan φ1 − tan φ2). It also compares apparent power and line current before and after correction. The capacitance result is an ideal sinusoidal estimate from Q = ωCV², with the selected single-phase, star or delta relationship.
How to use the result
Use the kVAr result as an initial capacitor-bank requirement, not as the final equipment rating. Select practical switched steps, verify the actual operating load profile and check whether over-correction can occur at light load. The current reduction is useful for screening upstream loading, but it does not change the active kW demand.
Method guide: Power Factor Correction Worked Example explains the kVAr, kVA and current relationships and the practical selection limits.
Engineering limits
Harmonic distortion, resonance, detuning reactors, capacitor tolerances, switching transients, utility limits and local compensation rules are not modelled. Drives, UPS systems and other nonlinear loads can require a detuned or filtered bank. Confirm the final design with the capacitor manufacturer and the applicable installation rules.
Before design release
Record the source and revision of every project input used in this calculation, then compare the result with the next practical equipment or conductor size rather than treating the numerical minimum as an automatic selection. Check tolerances, environmental derating, duty cycle, protection settings, installation constraints and manufacturer limits that are outside the simplified model. Where the result feeds another study, carry the same voltage, current, power-factor, fault-level and timing assumptions forward so the design chain remains traceable. Save the governing case and the reason for the final engineering choice. ElectroDesigner is intended to make the calculation path visible; it does not replace the project engineer’s verification, the adopted standard or tested manufacturer data.