Electrical

Power Factor Correction Calculator

Estimate reactive compensation and compare current before and after correction. Compare SI/US results and review the method, assumptions and related references below.

Change any input to update the calculation. Unit changes preserve the physical quantity.

CALCULATION SETUP

Inputs

Preset

AC supply

Need an input value?

Single & Three-Phase Power Reference ↗Common AC Voltage System Labels ↗

Supply voltage (line-to-line for three phase)

Need an input value?

Single & Three-Phase Power Reference ↗Common AC Voltage System Labels ↗

Real load power

Initial lagging power factor

Need an input value?

Single & Three-Phase Power Reference ↗Common AC Voltage System Labels ↗

Target lagging power factor

Supply frequency

Three-phase capacitor connection

Calculated locally in your browser. No sign-up or input upload.

YOUR CALCULATION

Results

Capacitor bank total

21.0658 kvar

Capacitance per phase

139.6969 µF

Current before

90.211 A

Current after

75.9671 A

Current reduction

14.2438 A

Reactive load before

37.5 kvar

Reactive load after

16.4342 kvar

Calculation breakdown

Result interpretation: Estimate reactive compensation and compare current before and after correction

Assumptions & checks

Only lagging sinusoidal loads. Harmonics, resonance, switching, leading power factor and bank protection require separate engineering.

Formula

Estimate reactive compensation and compare current before and after correction

Qc=P[tan(acos(PFbefore))−tan(acos(PFtarget))]. Cphase=Qc/(3ωVLL²) for delta, Qc/(ωVLL²) for wye; single phase Qc/(ωV²). Worked example: 50 kW improved from 0.80 to 0.95 needs approximately 21.066 kvar; at 400 V / 50 Hz delta this is 139.7 µF per phase.

Worked example

Using the default values shown in the calculator, the same formula gives the following result. This is a quick sanity check for the calculation, not a design recommendation.

Inputs

AC supply: Balanced three phase
Supply voltage (line-to-line for three phase): 400 V
Real load power: 50 kW
Initial lagging power factor: 0.8
Target lagging power factor: 0.95
Supply frequency: 50 Hz
Three-phase capacitor connection: Delta

Result

Capacitor bank total: 21.0658 kvar
Capacitance per phase: 139.6969 µF
Current before: 90.211 A
Current after: 75.9671 A
Current reduction: 14.2438 A
Reactive load before: 37.5 kvar
Reactive load after: 16.4342 kvar

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Technical references for this calculation

Reference lookupCommon AC Voltage System Labels Reference lookupSingle & Three-Phase Power Reference

Frequently asked questions

What does this result tell me?

Only lagging sinusoidal loads. Harmonics, resonance, switching, leading power factor and bank protection require separate engineering.

How can I check the calculation?

Worked example: 50 kW improved from 0.80 to 0.95 needs approximately 21.066 kvar; at 400 V / 50 Hz delta this is 139.7 µF per phase. Review each stated input and unit; use project-specific values rather than treating the editable example as a requirement.

Reference data & method sources

Schneider Electric power-factor correction
Lagging-load reactive-power difference. Capacitor connection is explicit; harmonic/resonance engineering is outside scope.
NIST SI conversion factors
SI/US dimensional conversions. Geometry and energy balances are stated explicitly, not attributed to a design standard.