FREQUENTLY ASKED QUESTIONS

Power Factor is a measure of how effectively incoming power is used in your electrical system and is defined as the ratio of Real (working) power to Apparent (total) power.

Real Power (KW) is the power that actually powers the equipment and performs useful, productive work. It is also called Actual Power, Active Power or Working Power.

Reactive Power (KVAR) is the power required by some equipment (eg. transformers, motors and relays) to produce a magnetic field to enable real work to be done. It’s necessary to operate certain equipment but you don’t see any result for its use.

Apparent Power (KVA) is the vector sum of Real Power (KW) and Reactive Power (KVAR) and is the total power supplied through the power mains that is required to produce the relevant amount of real power for the load. Let’s look at a simple analogy in order to better understand these terms. 

Let’s say you’ve ordered a glass of your favourite beer. The thirst quenching portion of your beer is represented by Real Power (KW). Unfortunately, along with your ale comes a little bit of foam that doesn’t quench your thirst, represented by Reactive Power (KVAR). The total contents of your glass (KVA) is this summation of KW (the beer) and KVAR (the foam). The power factor is the ratio between Real Power and Apparent Power. It’s expressed as a value between -1 and 1 and can be either inductive (lagging) or capacitive (leading). If the power factor is 1, then all of the power supplied is being used for productive work and this is called ‘unity’.

Therefore, for a given power supply (KVA):

• The more foam you have (the higher the percentage of KVAR), the lower your ratio of KW (beer) to KVA (beer plus foam). Thus, the poorer your power factor.
• The less foam you have (the lower the percentage of KVAR), the higher your ratio of KW (beer) to KVA (beer plus foam) and the better your power factor. As your foam (or KVAR) approaches zero, your power factor approaches 1.0 (unity).

A power factor of -0.7 for example, indicates that only 70% of power supplied to your business is being used effectively and 30% is being wasted. The wasted power is the Reactive power (the foam in the previous example). Most loads are inductive in nature, which means the power factor will typically be less than unity. The further the power factor is from unity, the greater the apparent power drawn and therefore, the greater the current draw for the system.

The increased current may require an increase in the size of your transformers and installation power wiring. Increased current also results in increased heat which affects the longevity and lifespan of an electrical system. This can add a great deal of cost to the installation and may also limit the expansion of a plant.

It’s important because you may be paying for reactive power (foam) that you cannot use to power equipment. If you can reduce the foam, you can get more ‘beer for your buck’. Improving the power factor results in less current being drawn, therefore less electricity costs, less heat and greater longevity of the electrical system.

Many power suppliers charge for the base load (kW) and a maximum demand tariff. If this maximum demand tariff is measured in kVA, then improving the power factor reduces the kVA of

the installation, thus reduces the maximum demand tariff and thereby reducing your power costs.

It is actually a network regulation that customers maintain a specific minimum power factor (values depend on your region). Utility companies may charge customers a penalty on top of consumption charges when customer power factor is less than a determined value.

Poor Power Factor can be improved by installing Power Factor Correction (PFC) equipment. Traditional solutions incorporate banks of capacitors that work as silent reactive power ‘generators’, often housed in a metal cabinet similar to the one that houses your electrical switchboard. Fuseco offers the latest generation of advanced performance PFC solutions that do not need a capacitor bank and offer many advantages due to their compact and modular configuration.

An electrical load with a poor power factor draws more current than a load with an improved power factor for the same amount of useful power transferred and can put unnecessary strain on the electricity distribution network. By improving your power factor, you can reduce your electricity bills through lower monthly demand and capacity charges. Typically payback periods for power factor correction are between 1-3 years. Given the life expectancy of power factor correction equipment and the potential savings, it can be a very worthwhile investment. Poor power factor may cause power losses and voltage drops, which can contribute to overheating and failure of motors and other equipment. If your electrical system is near capacity, installation of power factor correction equipment may help avoid costly infrastructure upgrades by lowering the existing electrical demand on your system and improving efficiency stability.

Due to the operational temperature and safety requirements applicable to capacitor banks, traditional PFC systems are constructed as a separate, stand-alone assembly or in self-contained spaces within the overall construction of the main switch board. This results in the common situation where PFC systems occupy a large space, often taking up valuable floor space in switch rooms.

Sinexcel have applied new generation thinking and innovative design principles to create a new generation of PFC solutions that do not use a switched capacitor bank system. This has redefined what is possible from a cost vs performance vs space perspective.

Sinexcel SVG are a modular design that are available in wall-mount, rack-mount and rack/cabinet configurations. This flexibility gives engineers multiple options to cater for all situations and ultimately save valuable space and floor real-estate.

Compensating kVAr Capability vs Space

• Up to 100kVAr capability from a wall-mount solution
• Up to 100kVAr capability from a single rack-mount module
• Up to 400kVAr capability from a single standard cabinet solution
• Up to 600kVAr capability from a single ‘drawer-type’ cabinet solution