Power Factor Correction

Power Factor Correction 2020-02-14T13:46:26+00:00

Power Factor Correction – Explained

What is Power Factor?

Power Factor is a way of describing how efficiently electrical power is consumed.  The power that is drawn from the network can be described as consisting of three parts – useful power, reactive power and true power. 

Useful power is the power that your electrical equipment requires to achieve the task in hand and is measured in kW.

Reactive power is drawn in addition to useful power by reactive loads, such as motors and is measured in kVAr.  Reactive power DOES NOT contribute to achieving the task but increases the current (amps) drawn to achieve the task.  This is the power we reduce with Power Factor Correction!

True power is the combination of useful power and reactive power and is measured in kVA.

Power Factor is the ratio of useful power (kW) to true power (kVA), with reactive power (kVAr) accounting for the difference.

Improving the Power Factor will reduce the true power (kVA) and reactive power (kVAr).  In the example below we have illustrated how improving the Power Factor on a 1000kW (useful power) load from 0.75 to 0.95 reduces the kVA (true power) and kVAr (reactive power) created.

Useful Power = 1000kW

Useful Power = 1000kW

PF = 0.75

PF = 0.95

Reactive Power = 882kVAr

Reactive Power = 392kVAr

True Power = 1333kVA

True Power = 1053kVA

Amps = 1855Amp

Amps = 1463Amp



Energy suppliers will charge most commercial and industrial customers for their true power (kVA) and penalise them for excessive reactive power (kVAr).  Lessening the reactive power (through Power Factor Correction) will reduce the true power (kVA) needed from the network to achieve the same task and remove the penalties being applied

What is Power Factor Correction?

Power Factor Correction, or PFC as it is often referred to is designed to reduce reactive power (kVAr) and improve the ratio between useful power (kW) and true power (kVA).  In most cases, poor power factor is caused by inductive loads, such as motors.  This can be compensated by introducing electrical devices called capacitors into the circuit.

Power Factor Correction is normally installed on the incoming electrical supply and reacts to load fluctuations, bringing capacitors into circuit as the load requires.  You simply set a target power factor and the automatic controls do the rest, ensuring the best possible power factor is achieved regardless of how the load fluctuates.

Power Factor Correction is connected in parallel to the main incoming supply meaning there is no need for a shutdown of your supply for installation and no disruption to your day to day business.

Why should I install Power Factor Correction?

Poor Power Factor has negative implications on businesses because it:

  • Draws more current from the network – costing more to achieve the same task
  • Can incur a ‘power factor penalty’ from your supplier, sometimes called a ‘reactive power charge’
  • Can lead to a business exceeding it’s arranged supply capacity and attracting penalties called ‘excess capacity charge’
  • Causes losses at transformers and other devices leading to unwanted heat gains, causing increased kWh consumption and carbon emissions
  • Reduces the effective capacity of the electrical infrastructure
  • Can cause excessive volt drops in the supply network
  • Can reduce the life expectancy of electrical equipment

What will I save?

Savings vary depending on how much power a business consumes and the existing power factor.  A typical uncorrected power factor for a commercial or industrial client would be between 0.70 – 0.80 and offers an excellent opportunity to achieve significant savings through the installation of Power Factor Correction.  The average payback for a Power Factor Correction project is around 2-years and savings can be many thousands of pounds per year.  There are also significant system benefits to your electrical infrastructure in reducing current draw on your electrical supply and freeing up capacity to add more electrical equipment.

What Next?

If you’re looking to reduce your electricity costs or free up capacity for new equipment, Power Efficient Solutions Ltd offer a free of charge, no obligation survey into the potential benefits from installing Power Factor Correction.  Leaving you free to run your business.

Contact us today for further information and to arrange a Power Factor Correction survey.