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What Is Power Factor Correction?

What Is Power Factor Correction

Power factor is the ratio between the true (useful) power kW to the apparent (total) kVA consumed by a complete electrical installation or piece of electrical equipment. It measures the efficiency of the electrical power and how much is useful electricity. The optimal power factor is unity or 1. This means that the electrical system is as efficient as possible in terms of useful energy used.

Anything less than 1 means that more power is required to achieve the task, thus costing more. Most energy companies charge a reactive power charge for companies with a power factor below 0.95. A load with 1.0 results in the most efficient loading of the supply, and a load with 0.8 results in much higher losses in the supply system and, consequently, a higher energy bill for the consumer.

See the lager analogy below for a visual analogy of a power factor less than 1. A full pint of lager is paid for; however, not all of the pints are ‘useful’, and the head is wasted energy. So it is more desirable to have a pint of lager with as little head as possible because you still get charged the same for that pint/ unit if it is useful to you or not. This is what power factor correction does for your power systems.

Johnson Phillips Power Factor Correction

What is Power Factor Correction?

Power Factor Correction (PFC) is a system installed to reduce the resistive and inductive losses (impedance) reducing the apparent reactive power vectors, this in turn produces a smaller phase angle which improves the power factor.

The Power Factor Correction Formula is simply the True Power divided by the Apparent Power. The end result is a figure between 0 and 1, with the best outcome being 1, which means the electrical system is as efficient as possible.

What Johnson & Phillips have to offer

Johnson & Phillips offer power analysis, site surveys and energy bill analysis to determine if a client requires power factor correction, we can also provide a comprehensive report of our findings and provide a proposal for a tailored solution. Johnson & Phillips manufactures, installs, retrofits and maintains bespoke power factor correction equipment for all applications.

Benefits of Power Factor Correction

There are many advantages associated with power factor correction, including:

Saving money – The installation of Power Factor Correction can make huge savings right from the start. If your power factor is 0.5 you are only 50% efficient so need twice as much electricity to power machines, by introducing power factor correction we could cut your electricity bill by up to 50% in this instance.

Reactive power charge – by installing power factor correction, you can reduce and, in most cases, eliminate your reactive power charge, which also saves the company money.

Using less energy – with increased power factor you have a supply of more ‘useable’ energy therefore the number of units used is reduced which also makes the company more economical.

More capacity – increasing the power factor also frees up more capacity so you can run more equipment on your existing power supply without the added expense of upgrading to a bigger supply- which can be very costly.


To conclude, having a poor power factor can not only cost more, but also affect your productivity. We often propose the payback for the system is less than a year – depending on your monthly energy usage.

Johnson & Phillips manufactures, installs, retrofits, maintains and repairs power factor correction units and can create bespoke units to suit your needs. We have worked in all sectors from; healthcare to manufacture, industry and recycling, we do it all. All our solutions are suitable a range of applications including 11kV transformer and others.