Power Factor Correction
Power factor correction raises the ratio of useful power (kW) to apparent power (kVA) toward unity, usually by adding capacitor banks that supply the reactive power inductive loads consume — cutting billed demand and penalties.
Why it matters on an MEPF project
Motors, transformers and old lighting draw reactive power that does no work but occupies capacity: cables, transformers and the DISCOM connection all size on kVA. Since industrial billing is demand-based in kVA and tariff orders penalise poor PF (and often reward high PF), correction is one of the fastest-payback investments in a factory — commonly months, not years.
Modern plants complicate it: harmonic-rich loads (VFDs, rectifiers) interact badly with plain capacitors, so detuned filter banks are the default for drive-heavy facilities, and APFC panels switch capacitor steps automatically as load moves. Correction placed at major loads also unloads your own cables and transformer, not just the billing meter.
How it's specified in practice
| Parameter | Typical / working position | Governing reference |
|---|---|---|
| Target PF | Near unity — per your tariff order's incentive/penalty bands | state tariff order |
| kVAr sizing | From kW and existing→target PF (calculable) | standard formula |
| APFC | Automatic step switching tracking load | IEC 61439-class panels |
| Harmonic-rich plants | Detuned/filter banks instead of plain capacitors | power-quality practice |
Common mistakes
- Fixed capacitors on a swinging load — over-correction at night, leading PF penalties.
- Plain capacitors in a drive-heavy plant — resonance and blown cans.
- Correcting only at the incomer and leaving internal distribution loaded.
- Dead capacitor steps discovered only when the penalty reappears.
Related on this site
Frequently asked
How much kVAr do I need?
It is a formula from your load kW and the PF journey (measured → target). Our power-factor calculator gives the kVAr and the annual saving from your bill numbers.
Why did my PF drop after adding VFDs?
Displacement PF may be fine while distortion (harmonics) degrades true PF — meters and tariffs increasingly see the latter. Measurement first, then detuned filters, is the correct sequence.
Standards referenced: state tariff orders · IEC 61439 (panels)