Calculateur de Dimensionnement de Disjoncteur
Calculez le calibre de disjoncteur nécessaire.
Required Capacitor Bank
110.6 kVAR
Required Capacitor Bank vs Real Power (P)
Formule
Power Factor Correction with Capacitors
Capacitor banks supply reactive power locally, reducing the reactive current drawn from the supply.
Formula
Q_c = P (tan(phi_1) - tan(phi_2))
where P is real power, phi_1 = arccos(PF_old), phi_2 = arccos(PF_new). Equivalently: tan(phi) = sqrt(1/PF^2 - 1).
Exemple Résolu
Improve power factor from 0.75 to 0.95 on a 200 kW load.
- 01tan(phi_1) = sqrt(1/0.75^2 - 1) = sqrt(0.778) = 0.882
- 02tan(phi_2) = sqrt(1/0.95^2 - 1) = sqrt(0.108) = 0.329
- 03Q_c = 200 x (0.882 - 0.329) = 200 x 0.553 = 110.6 kVAR
- 04Select 120 kVAR capacitor bank (next standard size).
Questions Fréquentes
Should I correct to unity power factor?
Generally no. Correcting to exactly 1.0 is expensive and can cause leading power factor during light load conditions, which may create voltage rise issues. Target 0.92-0.97 for best economics.
What types of capacitor banks are available?
Fixed banks provide constant correction. Automatic (switched) banks use a controller to switch capacitor stages in and out as load varies. Automatic banks are preferred for varying loads to avoid over-correction.
Can capacitors cause harmonic problems?
Yes. Capacitors can resonate with system inductance at harmonic frequencies, amplifying harmonics. In systems with significant harmonic content (VFDs, rectifiers), use detuned capacitor banks with series reactors.
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