Electrical
Power Factor Correction: What It Is and Why Businesses Should Care
Short answer
Power factor is the ratio of useful power (kW) to total power drawn (kVA). Motors and transformers lower it. A low power factor wastes supply capacity, heats cables and can attract extra charges on some commercial tariffs. A capacitor bank sized from a load survey raises power factor, usually towards 0.95 or better.
The idea in plain words
Think of a glass of beer: the liquid is useful power (kW), the foam is reactive power (kVAr) and the whole glass is kVA. Power factor = kW ÷ kVA. Induction motors, welders and transformers need reactive power, which lowers the ratio.
Why it matters
- Higher current for the same useful power, so cables and transformers run hotter.
- Less spare capacity on your supply.
- Possible penalties or reactive charges depending on the tariff; check your bill.
- Larger generator and cable sizes.
How it is corrected
- Measure power factor and load patterns over time.
- Calculate the reactive power to be compensated.
- Choose a fixed or automatic capacitor bank, with detuning reactors where harmonics exist.
- Install with proper protection and check it regularly.
Harmonics warning
Variable speed drives, UPS units and LED drivers create harmonics, and plain capacitors can resonate with them. Have the correction designed and tested rather than guessed. See our industrial electrical services.
Common questions
What is a good power factor?
Most utilities and designers aim for about 0.9 to 0.95 or above.
Do homes need power factor correction?
Normally no. It matters mainly for businesses with large inductive loads.
Does correction reduce my units used?
It reduces current and losses and may avoid charges, but it does not reduce the kWh your equipment needs.