EngineerHub.orgDrawing No. EH–EE–018 // Electrical Engineering
Power Factor Correction Calculator
Reviewed August 2026
Size a capacitor bank from present and target power factor, then see the effect on kVA, current and capacitance.
01 // Electrical load
02 // Capacitor-bank requirement
Background & method
The fundamental relation is Qc = P(tan φ1 − tan φ2). The calculator then derives current and capacitor values for the selected electrical configuration. Harmonic and switching design remains a separate engineering task.
FAQ
Qc = P[tan(arccos PF1) − tan(arccos PF2)]. It is the reactive power that must be supplied locally to move from the existing to the target power factor.
Loads vary. Correcting exactly to unity at one operating point can produce leading power factor at lighter load. Automatic stepped banks are commonly used for variable loads.
Capacitor banks can resonate with system inductance and amplify harmonic currents. Harmonic surveys, detuned reactors or filtered banks may be needed.