Calculators › Electrical power and motors Additional reactive compensation calculator
Additional reactive compensation
Additional capacitor capacity is the reactive compensation needed to reach the target power factor at unchanged real load, less the capacitor capacity already operating.
Q add = P × ( 1 − P F 1 2 P F 1 − 1 − P F 2 2 P F 2 ) − Q existing Q_{\text{add}} = P \times \left(\frac{\sqrt{1 - \mathrm{PF}_{1}^{2}}}{\mathrm{PF}_{1}} - \frac{\sqrt{1 - \mathrm{PF}_{2}^{2}}}{\mathrm{PF}_{2}}\right) - Q_{\text{existing}} Q add = P × PF 1 1 − PF 1 2 − PF 2 1 − PF 2 2 − Q existing
Calculator
Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.
Worked example
Given
P P P 500 kW P F 1 \mathrm{PF}_{1} PF 1 0.75 — P F 2 \mathrm{PF}_{2} PF 2 0.95 — Q existing Q_{\text{existing}} Q existing 100 kVAR Q add = 500 × ( 1 − 0.75 2 0.75 − 1 − 0.95 2 0.95 ) − 100 ≈ 176.6 Q_{\text{add}} = 500 \times \left(\frac{\sqrt{1 - {0.75}^{2}}}{0.75} - \frac{\sqrt{1 - {0.95}^{2}}}{0.95}\right) - 100 \approx 176.6 Q add = 500 × ( 0.75 1 − 0.75 2 − 0.95 1 − 0.95 2 ) − 100 ≈ 176.6
Symbols and units
Symbol Meaning Unit
Q add Q_{\text{add}} Q add additional capacitor capacity kVAR P P P unchanged real load kW P F 1 \mathrm{PF}_{1} PF 1 initial uncorrected power factor — P F 2 \mathrm{PF}_{2} PF 2 target power factor — Q existing Q_{\text{existing}} Q existing operating existing capacitor capacity kVAR
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