How the calculation works
kVAR = kW × (tan θ₁ − tan θ₂), θ = arccos(PF). Capacitors: NEC Article 460 (conductors ≥135% of rated capacitor current, 460.8; disconnect and discharge per 460.6/460.28). CEC Section 26 Part ... applies in Canada.
Worked example
100 kW, PF 0.80→0.95: ≈42.1 kVAR.
Common mistakes to avoid
- Over-correcting into a leading power factor.
- Ignoring harmonics from drives and rectifiers.
- Sizing for peak load instead of typical running load.
Frequently asked questions
Harmonics?
With VFDs or nonlinear loads, use detuned reactors; plain capacitors risk resonance.
Why correct power factor?
Utilities may bill a penalty for low power factor, and lower current reduces conductor losses and voltage drop.
What target power factor should I use?
Usually 0.95 to 0.98. Avoid going above unity-equivalent leading conditions at light load.
Read the guide
Power Factor Explained: kW, kVA, kVAR and Capacitor Sizing
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