What power factor actually is
Motors, transformers and fluorescent gear draw two kinds of current: the real current that does useful work (kW) and the reactive current that builds the magnetic fields they need but does no work (kVAr). Together they make the apparent current the supply must actually carry (kVA). Power factor is the ratio of useful to total — kW ÷ kVA — and a low power factor means you are drawing a lot of reactive current for not much useful output.
A site full of induction motors can sit at a power factor of 0.7-0.8. That reactive current still heats your cables, loads your transformer and travels back to KPLC — who charge you for it.
How the KPLC penalty works
Kenya Power meters reactive energy and applies a reactive-power charge when your power factor falls below a threshold. The poorer your power factor, the bigger the penalty line on your bill. Many businesses pay this every month without realising it is both avoidable and a symptom of wasted capacity.
The fix: a capacitor bank
A power factor correction (PFC) capacitor bank supplies the reactive power locally, right where the motors need it, so it no longer has to be drawn from (and paid to) the grid. An automatic bank switches capacitor steps in and out to track the changing load, holding the power factor near target all day.
The result is a smaller measured demand (kVA), a lower or eliminated reactive charge, reduced voltage drop, and freed-up transformer and cable capacity — sometimes deferring an expensive supply upgrade.
Sizing the correction
The reactive power (kVAr) of capacitors needed to move from an existing power factor to a target is:
Q_c = P × (tan φ₁ − tan φ₂)
…where P is your real power (kW), φ₁ is the angle at your current power factor and φ₂ the angle at the target.
Worked example: correcting a 200 kW load from 0.75 to 0.95 needs Q_c = 200 × (0.882 − 0.329) ≈ 111 kVAr of capacitors.
The harmonics caveat
On modern sites with VFDs, UPS rectifiers and lots of electronics, plain capacitors can resonate with the harmonic currents and amplify them — causing more trouble than they cure. The solution is a detuned (reactor-protected) bank. This is why we always measure the harmonic content before specifying correction, rather than just bolting on capacitors.
The bottom line
If your KPLC bill shows a reactive-power charge, you are paying a penalty that a correctly sized capacitor bank usually eliminates within a year — while making your whole installation run cooler and freeing capacity for growth.
Send us a recent KPLC bill and we will tell you whether you are being penalised and size the correction. Call +254 768 860 665 or +254 782 914 717.