POWER · CALCULATOR

Transformer power factor correction calculator

Free transformer power factor correction calculator: get compensation required from active load, initial power factor and target power factor.

Written by Chameera Sampath · Not yet reviewed by a licensed electrician. See the methodology.

US (NEC) only · NFPA 70 / NEC — locally adopted editionDefaults are US values. Verify the locally adopted NEC edition and project data.Official reference ↗

Project inputs

Measurements

Active load

Initial power factor

Target power factor

Updates as inputs change. Unit changes preserve the same physical values.

THE MATH BEHIND THE ANSWER

Method & assumptions

Qc = P × [tan(acos PF1) − tan(acos PF2)]

Steady-state displacement correction. Target must exceed initial PF. Transformer no-load compensation requires manufacturer data; check resonance and harmonics.

Results do not check every aspect of an electrical installation. The calculators follow US (NEC) practice only; a regional preset changes defaults such as voltage and units, and no result certifies NEC compliance.

Sources and validation →

Worked example

Active load: 30 kW · Initial power factor: 0.75 · Target power factor: 0.95

Compensation required: 16.597 kvar

This example uses the stated inputs; results for the entered values appear above.

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