Complete Guide to Power Factor
The Power Factor Calculator computes kW, kVA, kVAR, and capacitor size for PF correction. Supports single/three-phase, lagging loads. Our free tool helps reduce utility penalties and improve efficiency.
What is Power Factor?
PF = P / S = cos(θ), where P = real power (kW), S = apparent power (kVA). Ideal = 1.0. Low PF = high current, penalties. Our Power Factor Calculator includes correction.
Why Improve Power Factor?
Benefits:
- Lower Bills: Avoid PF charges.
- Reduced I²R Loss: Less heat.
- More Capacity: Same transformer.
- Compliance: IEEE 18, NEC.
Use with Capacitor Sizing and Energy Cost.
Power Factor Formulas
- Single-Phase: kVA = V × I / 1000, kW = kVA × PF
- Three-Phase: kVA = √3 × V × I / 1000
- kVAR = √(kVA² - kW²)
- Capacitor kVAR = kVAR_existing - kVAR_target
Power Triangle
| Component | Symbol | Unit |
|---|---|---|
| Real Power | P | kW |
| Reactive Power | Q | kVAR |
| Apparent Power | S | kVA |
Typical Power Factors
| Load Type | PF Range |
|---|---|
| Incandescent Lights | 1.0 |
| LED Lights | 0.9–0.95 |
| Induction Motors (full) | 0.8–0.85 |
| Motors (50% load) | 0.6–0.7 |
| Welders | 0.5–0.6 |
How to Correct Power Factor
Steps:
- Measure: PF meter.
- Calculate: kVAR needed.
- Install: Capacitors at load or MCC.
- Verify: PF > 0.95.
Example: 480V, 100A, PF 0.8 → 83 kVA, needs 31 kVAR.
Capacitor Sizing Formula
kVAR = P × (tan(θ₁) - tan(θ₂))
C (μF) = kVAR × 10⁶ / (2πfV²)
Practical Applications
Use for:
- Factories: Motors, pumps.
- Commercial: HVAC, lighting.
- Utilities: Avoid penalties.
- Renewables: Inverter PF.
Tips for Correction
- Avoid Overcorrection: Leading PF.
- Harmonics: Use detuned reactors.
- Automatic Banks: Varying loads.
- Location: Near inductive loads.
Common Mistakes
- Wrong Phase: Use √3.
- Ignore Harmonics: Capacitor damage.
- No Fusing: Safety risk.
- Overcorrect: Resonance.
Advanced Topics
- Harmonics: THD > 5%.
- Active PFC: VFDs, SMPS.
- IEEE 519: Compliance.
- Energy Savings: ~2% per 0.1 PF.
Conclusion
Power factor correction saves money and improves system capacity. Our Power Factor Calculator delivers instant kVAR and capacitor sizing. Combine with Energy Cost and Construction tools. Optimize efficiency with 1000 Calculators.