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Power Factor Correction Calculator

Assumes constant active electrical power and a balanced sinusoidal load with an initially lagging power factor. Enter power factors as decimals from above 0 to 1; target must be at least the present value.

Local calculation · inputs stay in your browser

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    Formula and method

    Qc = P[tan(arccos PF₁) − tan(arccos PF₂)] in kvar; I = 1000P/(√3 Uline PF). Per branch: CΔ = 10⁹Qc/(3 × 2πfUline²), CY = 10⁹Qc/(2πfUline²) in µF. Use kW, V and Hz.

    Worked example

    100 kW, PF 0.75 to 0.95, 400 V, 50 Hz, delta: approximately 55.323 kvar; line current 192.450 A to 151.934 A; 366.874 µF per branch.

    Assumptions and limits

    • Capacitance is for each of three identical branches, not their sum. For the same voltage, frequency and total kvar, each star branch needs three times the delta capacitance.
    • This is a preliminary estimate. Electrical design must verify voltage ratings, harmonics, resonance, reactors, switching steps, protection and motor self-excitation. Do not connect correction capacitors directly to a VFD output.
    • Compensation does not change load active power in this model. The current reduction is not a percentage saving in energy or bills; actual savings depend on line losses and tariff terms.

    Frequently asked questions

    Does 50 Hz versus 60 Hz change the required kvar?

    With fixed active power and power factors, required kvar is unchanged. The capacitance needed to supply it is inversely proportional to frequency.

    Why not always target 1.00?

    Load variation may cause overcompensation and a leading power factor. A target of 1 is an ideal mathematical boundary; practical design depends on the load profile and switching control.

    References

    Power Factor Correction Calculator practical guide and common questions

    What does Power Factor Correction Calculator calculate?

    Assumes constant active electrical power and a balanced sinusoidal load with an initially lagging power factor. Enter power factors as decimals from above 0 to 1; target must be at least the present value. Qc = P[tan(arccos PF₁) − tan(arccos PF₂)] in kvar; I = 1000P/(√3 Uline PF). Per branch: CΔ = 10⁹Qc/(3 × 2πfUline²), CY = 10⁹Qc/(2πfUline²) in µF. Use kW, V and Hz.

    When is this useful?

    100 kW, PF 0.75 to 0.95, 400 V, 50 Hz, delta: approximately 55.323 kvar; line current 192.450 A to 151.934 A; 366.874 µF per branch.

    How do I enter the inputs?

    Enter the inputs for Power Factor Correction Calculator: Active electrical load power (three-phase total), Present lagging power factor, Target power factor, Supply frequency, Line voltage (line-to-line RMS), Connection of three equal capacitors. Calculate, check the units and assumptions, then copy or download the results.

    How should I interpret the results?

    Capacitance is for each of three identical branches, not their sum. For the same voltage, frequency and total kvar, each star branch needs three times the delta capacitance. This is a preliminary estimate. Electrical design must verify voltage ratings, harmonics, resonance, reactors, switching steps, protection and motor self-excitation. Do not connect correction capacitors directly to a VFD output. Compensation does not change load active power in this model. The current reduction is not a percentage saving in energy or bills; actual savings depend on line losses and tariff terms.

    Where are my inputs processed?

    Power Factor Correction Calculator runs in this browser. Inputs are not uploaded to a calculation server; copying and CSV download require your action. The existing site analytics and advertising still load.