Power Management

Power Factor Correction: An Overlooked but Powerful Tool for Delivering Energy Efficiency and Cost Savings


Amid all the talk about how to reduce CO2 emissions and limit climate change, renewable energy sources such as wind and solar often take center stage. But there’s another technology poised to deliver energy reductions of 10% or more that gets far less attention: power factor correction (PFC).

If you’re not familiar with PFC you are far from alone. To date, it’s been a largely overlooked method of reducing energy consumption, costs, CO2 emissions and achieving sustainability. But PFC is actually far more effective than many “green” alternatives because it effectively enables companies to get more power out of the same amount of utility electricity.

Understanding power factor

I won’t kid you: PFC is a bit complicated to explain and understand, making a full discussion of it beyond the scope of this post. You can learn all about it from this free Schneider Electric paper titled “Energy efficiency improvement through optimization of the power factor correction.”

But the basic concept is it takes more to energy to power a given load than the actual power that the load consumes. That’s because some of the energy is lost in translation, so to speak. Power factor is used to determine just how much more energy will be required to power the load. That amount is measured by calculating a ratio that shows how efficient any given machine is. A motor with a power factor of .90, for example, is 90% efficient. To determine how much energy you’ll need in kVA to power that machine, you perform an equation: 100 (for a 100kW motor) ÷ 0.90 = 111kVA. So you’ll need 111kVA of utility power to run that 100kW motor.

Saving energy with power factor correction

Obviously, the lower your power factor of a given piece of equipment, the less efficient it’s going to run. And that inefficiency can cost you more than just a higher utility bill because in some areas, you’ll get penalized for consuming more power than your contract allows, taking into account your power factor.

The key to ensuring that doesn’t happen is to use a capacitor bank or energy compensator. These systems perform PFC to help reduce the amount of power an AC device has to consume to generate its rated amount of power. Some systems, such as VarSet low-voltage capacitor banks from Schneider Electric, automatically correct power factor. This results in a power factor close to 1, meaning virtually no power is wasted.

Using PFC systems can deliver a number of benefits, including:

  • Significant savings on electricity bills, with ROI typically within two years (actual savings vary depending on local utility penalties)
  • Improved energy efficiency
  • Attained sustainability goals
  • Reduced energy use waste
  • Increased available power at your facility
  • Reduced carbon footprint
  • Improved equipment reliability and lifespan by filtering “dirty power”

Sounds an awful lot like many of the same benefits that solar and wind deliver, doesn’t it? The savings can indeed be impressive, and they’re relatively simple to achieve. To learn more about power factor correction in your facility, email: powersolutions@schneider-electric.com


One Response
  1. Jacques Schonek

    I agree that PFC may be difficult to explain, but oversimplification is not a suitable answer.
    In the given example of a motor with a 0.90 Power Factor, there is a confusion between Power Factor and Efficiency, and between Power and Energy.
    Let’s take another example, with different figures for Efficiency and Power Factor.
    For a 100kW motor (100kW is the mechanical power delivered on the shaft), a typical value for Efficiency is 0.95, and a typical value for Power Factor is 0.85.
    This means that the electrical power to be supplied to the motor is 100/0.95 = 105 kW (5kW of power is lost mainly as heat).
    The apparent power is then 105/0.85 = 124kVA. This means that the current to be supplied by the Utility is more than necessary. And this “overcurrent” is responsible for additional power losses in the cables, switchgear, transformer, power lines, … upstream of the motor. This why many Utilities apply penalties for low values of Power Factor.
    See also “Did you know that it is possible to save CO2 by connecting capacitors to the electrical networks?” in this blog.


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