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CALC 09 · POWERPRO

Power Factor Correction

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SYSTEM PARAMETERS
kW
Poorcos φ = 0.70 (45.6°)
Excellentcos φ = 0.95 (18.2°)
ECONOMIC ANALYSIS
$/kVAR

Typical: $10-20/kVAR

$/kWh

Typical: $0.08-0.15/kWh

APPLICATION PRESETS
CALCULATION SHEET
Required Capacitor Bank
69.15 kVAR
1524 μF

Power Factor Improvement

70%
Before
95%
After

Economic Benefits

kVA Reduction:37.6 kVA
Demand Charge Savings:$563.91/month
Energy Loss Savings:$145.47/month
Total Monthly Savings:$709.38
Yearly Savings:$8512.55

Return on Investment

Capacitor Cost:$1037.28
Installation Cost:$311.18
Total Investment:$1348.46
Payback Period:1.9 months✓ Excellent ROI
Derivation
  1. 01Real Power: 100 kW = 100000 W
  2. 02Current power factor: 0.7 (70.0%)
  3. 03Current reactive power (Q1): 100000 × tan(cos⁻¹(0.7)) = 102020.41 VAR
  4. 04Target power factor: 0.95 (95.0%)
  5. 05Target reactive power (Q2): 100000 × tan(cos⁻¹(0.95)) = 32868.41 VAR
  6. 06Required capacitor: Qc = Q1 - Q2
  7. 07Qc = 102.02 - 32.87 = 69.15 kVAR
  8. 08Capacitance: C = Qc / (2π × f × V²)
  9. 09C = 69151.99560415442 / (2π × 50 × 380²) = 1.524e-3 F
  10. 10C = 1524.36 µF
  11. 11kVA Reduction: 142.86 - 105.26 = 37.59 kVA
  12. 12Improved power factor reduces utility demand charges!
REFERENCE — BENEFITS OF PF CORRECTION
Reduce electricity demand charges (10-30% savings)
Lower I² R losses in cables (reduced heat)
Increase system capacity (can add more load)
Improve voltage regulation (less voltage drop)
Reduce transformer loading (extend equipment life)
Avoid utility penalties (many utilities charge for low PF)
Important Notes

• Do not over-correct (PF > 1.0 creates leading power factor issues)

• Use automatic PF controllers for variable loads

• Install harmonic filters if non-linear loads present

• Consider detuned capacitors for systems with VFDs

• Annual maintenance required (check capacitor condition)