• Dale Rouessart

What is Power Factor and how does it affect me?

In this article we will take a brief look at Power Factor. We will look at how it is calculated and the effects on your bill and infrastructure. Power factor can be a complex concept, but it is does not need to be. For a lot of Companies that have demand that spikes and falls Power Factor Correction has become their friend saving them approx. 20% of their electricity bill straight off the top… instantly increasing profit.


What is power factor?


Power factor refers to the ratio of power supplied to the measurement points (measured in kilowatts or kW) to the demand pulled from the supply (measured in kilovolt-amperes or kVA). An ideal system would have a power factor of 1 (or unity). This means that the demand exactly equals the power, but in the real world you can see power factors running from as low as 0.55 to 0.999. For example, if your Power Factor is running at 0. 75, you are losing a theoretical 25% of your electricity in Reactive Energy. The lower it is, the more you are losing. Of course, there is an “acceptable” loss of 2 – 4 % due to loss in the system’s wiring etc but should be monitored regularly to make sure your system is as efficient as possible. A very good way to explain Power Factor is the Beer Analogy.


When does power factor affect me?


There are very specific situations where a power factor is relevant:


  • There is Demand Charge. It increases the maximum demand portion of your bill If there is no maximum or peak demand line item that is measured in kVA this is not relevant. In most medium and large commercial scale buildings it will be present.

  • There is Reactive Energy. It increases reactive energy supplied – this is a very specific line item that is only present in a small portion of bills we evaluate.

  • There are Network Charges. It increases availability-based charges such as Network Access Fees – this is a fee based on the maximum contracted demand you expect to use.

  • You exceed you Demand constantly. If you want to increase the load on site without increasing your breaker size. If you want to upgrade or downgrade, ensure you have detailed and accurate measurement data to work with.

Low power factor does not increase your energy use (or kWh). This means that if the only thing you are billed for is energy, that improving the power factor will not have any benefit to your billing. A power factor surcharge is applied to your account when your power factor is below 90%. It is used to recover the cost of supplying reactive power to you, which isn’t included in other charges.


Causes of poor power factor


  • Large inductive loads such as power transformers and electric motor driven loads such as fans, pumps and air compressors may cause poor power factor.

  • Additionally, loads that draw current in a non-linear fashion, such as variable speed drives, computers, broadcasting equipment, compact fluorescent and LED lighting, electrical chargers, induction furnaces and many other devices may also contribute to low power factor in a customer's system.


How do I improve my power factor?


An Archon Power Factor Correction Unit is a simple system that ties into your electricity distribution system. It regulates the power factor by bringing suitably sized capacitors in and out of the system depending on load. The capacitors act like batteries and store your Reactive Energy for when your system needs it. When your systems needs to pull (the demand), the capacitors kick in and ease the load on the system and subsequently suppress the “spikes” that cause you to exceed your demand. The system is specifically designed for your site’s operating profile. Installation is quick and easy and does require maintenance from time to time. Reactive power elements such as capacitors and synchronous generators and motors can help overcome issues involving low Power Factor values.


Archon is fortunate enough to have a team of Electrical Engineers that are renowned for designing and producing reliable and very efficient Power Factor Correction Units that will work hard for you for years to come. We have been privileged enough to have been involved in some major projects in Africa where we have designed, procured and installed Power Factor Correction Units, Sub-Stations and Transformers to the required specification and international standards.


How do I determine if my power factor is bad?


The best way is to meter the data over a significant period (you should also measure during peak operating times). The Archon energy intelligence platform has comprehensive reporting built in that simplifies your power factor to an “opportunity cost”.


Power factor correction equipment is installed in the main DB or next to it depending on the size required, with a display showing the power factor to two digits. You may have a low power factor during off-peak times, but this is not as important as the power factor during high load conditions. When you are operating at full capacity this should be ideally hovering close to the unity figure of 1.


Most of our clients in the office environment run at about 0.85 to 0.95 before correction depending mostly on the HVAC system as your computer hardware is generally quite light on the demand side. Most of the production facilities we monitor run from 0.75-0.9 before correction and this is mostly a result of the number and size of motors pulling during production. Older machines generally are not as efficient as the modern equipment so you can assist your system by upgrading or replacing old workhorses with their nimbler counterparts.


A low Power Factor indicates an imbalance that manifests itself as a phase shift between the voltage and current signals in a power supply. This may or may not be an issue. However, it’s possible that the power supply may dip, and for the heavy motor user, the utility company may not respond in kind.


Good places to start your investigation


  • Large fans and motors (especially if they are only partially loaded).

  • Equipment with a high number of transformers (such as lighting ballasts).

  • Failed or improperly sized capacitors (used for power factor correction).

  • Harmonics in a system caused by non-linear electrical loads.


At Archon we offer solutions that effectively measure and manage energy efficiency. Our main aim is to improve operations and longevity of your prized assets, and ultimately increase your profitability. We offer 35 years of leading expertise in the fields of energy management, utility management, power factor correction, water management and municipal and tenant billing disputes.


From both a high energy user perspective to shopping centres and business park tenant billing solutions, our clients are constantly making us push the envelope to deliver more efficient and accurate systems that make their lives easier and their companies more environmentally responsible. This is becoming more important as we continually strive to lower our carbon footprint and ensure a sustainable future for our planet.

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