Free Capacitor Bank Calculator

Calculate the capacitor bank kVAR needed to improve power factor to a target value.

kW

Required Capacitor Bank

110.6 kVAR

Apparent Power Before266.7 kVA
Apparent Power After210.5 kVA

Required Capacitor Bank vs Real Power (P)

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).

Example Calculation

Improve power factor from 0.75 to 0.95 on a 200 kW load.

  1. 01tan(phi_1) = sqrt(1/0.75^2 - 1) = sqrt(0.778) = 0.882
  2. 02tan(phi_2) = sqrt(1/0.95^2 - 1) = sqrt(0.108) = 0.329
  3. 03Q_c = 200 x (0.882 - 0.329) = 200 x 0.553 = 110.6 kVAR
  4. 04Select 120 kVAR capacitor bank (next standard size).

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