Power Factor Correction Calculator
Calculate capacitor bank size to improve power factor and reduce reactive power
Reference Info & Formulas
Poor power factor increases apparent power (kVA) and current draw without doing useful work.
Benefits:
- Lower electricity bills (reactive power charges)
- Reduced cable losses (I²R)
- Freed-up transformer capacity
- Lower voltage drop
0.85: Motors, compressors
0.65: Welding equipment
0.80: Fluorescent lighting
0.95+: LED lighting, resistive loads
Data: Power triangle formulas — kVAr = kW × (tan(arccos PF₁) − tan(arccos PF₂))
For guidance only. The responsibility for any electrical installation lies with the qualified person carrying out the work. Always verify calculations independently and apply professional judgement.
How Power Factor Correction Works
Power factor is the ratio of real power (kW) to apparent power (kVA). A low power factor means more current is drawn to deliver the same useful work.
Qc = P × (tan(arccos PF₁) − tan(arccos PF₂))- Qc
- = Required capacitor kVAr
- P
- = Active power in kW
- PF₁
- = Current (poor) power factor
- PF₂
- = Target (improved) power factor
Power triangle relationship
Capacitors supply reactive power locally, reducing the reactive current drawn from the supply. This lowers apparent power (kVA), reduces line current, and improves voltage regulation throughout the installation.
Quick Reference — Correction kVAr per kW
Multiplier table: kVAr = kW × factor
Standard power factor correction tables| Current PF | Target 0.90 | Target 0.95 | Target 0.98 | Target 1.00 |
|---|---|---|---|---|
| 0.70 | 0.54 | 0.69 | 0.80 | 1.02 |
| 0.75 | 0.40 | 0.55 | 0.66 | 0.88 |
| 0.80 | 0.27 | 0.42 | 0.53 | 0.75 |
| 0.85 | 0.13 | 0.29 | 0.40 | 0.62 |
| 0.90 | — | 0.16 | 0.27 | 0.48 |
Multiply active power (kW) by the factor to get required kVAr.
Installation Considerations
Overcorrection Risk
Harmonic-Rich Environments
Frequently Asked Questions
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