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Power-Factor Correction kvar

Also known as capacitor bank sizing · PF correction

Qc=P(tan⁡φ1−tan⁡φ2)Q_{c} = P \left( \tan\varphi_{1} - \tan\varphi_{2} \right)
sig figs

Worked example: 100 kW from 0.70 to 0.95 PF → 69.15 kvar. Press Try an example to run it live, then adjust anything.

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Power-Factor Correction Capacitance
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See also

Power Factor from Real and Apparent Power: Both use load real power and existing power factor.Single-Phase Real Power with Power Factor: Both use load real power and existing power factor.Three-Phase Real Power: Both use load real power and existing power factor.Power-Factor Correction Capacitance: Both use correction reactive power.Phase Angle from Power Factor: Both use existing power factor.Three-Phase Motor Full-Load Current: Both use existing power factor.
1 more relatedTransformer Efficiency from Core and Copper Losses: Both use existing power factor.
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Power-Factor Correction kvar explained

QcPF₁PF₂P

Each power factor corresponds to a phase angle φ = arccos(PF), and the reactive burden of a load is P tan φ. To move from a poor PF₁ to a target PF₂ you must cancel the difference in those vars, which is what a capacitor bank does. A 100 kW plant at 0.70 PF carries 100 × 1.020 = 102 kvar; at 0.95 PF it would carry only 32.9 kvar, so about 69 kvar of capacitors closes the gap.

Two field cautions. Chasing unity is a mistake: the last few points cost the most capacitors, and an overcorrected plant goes leading, which can push voltage up and, on a motor that keeps spinning after the contactor opens, cause damaging self-excitation. And where the harmonic content is high, plain capacitors resonate with the supply inductance and amplify the harmonics; detuned reactors are then part of the package.

Power-Factor Correction kvar formula

Qc=P(tan⁡φ1−tan⁡φ2)Q_{c} = P \left( \tan\varphi_{1} - \tan\varphi_{2} \right)
Where
  • QcQ_{c}= Correction reactive power (var) (W)
  • PP= Load real power (W)
  • PF1\text{PF}_{1}= Existing power factor
  • PF2\text{PF}_{2}= Target power factor
In this toolkit

Three-phase power and power factor

8 formulasReal, reactive and apparent power, power factor, phase angle and correction kvar — the power triangle as an electrician uses it.

Revised 16 October 2026
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formula.expert. (2026, October 16). Power-Factor Correction kvar Formula & Calculator. https://formula.expert/solvers/power-factor-correction-kvar

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