Power Factor Correction beer analogy

What is Power Factor Correction

Power factor correction is the process of compensating for the lagging current by creating a leading current by connecting capacitors to the supply. A sufficient capacitance is connected so that the power factor is adjusted to be as close to unity as possible. Power factor explained.
That sounds alll very technical so lets use the beer anaology.
Power factor is the ratio between the active power (kW) and the apparent power (kVA). Using the beer analogy, we obtain the power factor by dividing the beer by the mug capacity, and it’s clear, you’re getting less beer than you’re paying for with all that foam taking up space.

PFC unit installed at Haileybury Rendal School, Berrimah, NT

The Benefits of Power Factor Correction That Can Impact Your Business Operations

  • Preventing Power Factor Penalties.
  • Reduce Demand Charges.
  • Increase Capabilities of Existing Circuits.
  • Better Voltage.
  • Lower Power System Losses.

WHY DO WE NEED POWER FACTOR CORRECTION?

Are you wasting power?
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. 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.
Power Factor Correction
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WHY DO WE NEED POWER FACTOR CORRECTION?

Why is Power Factor Correction important?

  • It’s important because you may be paying for reactive power (foam in the beer example) 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.

Are you wasting power?

  • 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. 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.

How can Power Factor Correction help you?

  • 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.

Types of Power Factor Correction

Simple power factor correction solutions incorporate banks of capacitors that work as silent reactive power ‘generators’. These systems were designed many decades ago when electrical environments were a lot simpler than they are today. They are common, very economical and suitable for linear load environments.
However, in today’s modern electrical environments, linear loads are not easy to find. Due to the proliferation of LED/energy efficient lighting, switch-mode power supplies, VSD’s, UPS’s, servers/computers and typical appliances, today’s electrical systems experience complex, dynamic non-linear loads. Loads are being switched so fast that the traditional capacitor bank PFC systems struggle to maintain an effective compensation set-point. Therefore, they are perpetually ‘chasing’ the load, either under or over-compensating but rarely providing effective compensation.
Sunoxi offers the latest generation of advanced performance PFC solutions that offer instantaneous, dynamic step-less compensation, ideal for the challenging demands of modern electrical environments. The Sinexcel SVG solutions do not need a capacitor bank and offer many advantages due to their compact & modular configuration (including wall-mount options)
  • Static Var Generators
  • Capacative

Static Var Generators (SVG’s)

Sinexcel SVG
This screen shot is from a Sinexcel SVG unit operating at one of our customer locations.
The Load Current information in the bottom left of the screen displays the actual load, RMS (Amps) of the site, the PF (Power Factor) and the THDI (Total Harmonic Distortion Current).
There are 2 important factors to note here. Firstly, this site has a significant phase current imbalance. The RMS between the 3 phases ranges from 858.9A to 816A. That is a 42.9A phase current imbalance. Secondly, the PF ranges from 0.842-0.858 across the three phases which is considered poor and correction is required.
The Grid Current information at the top left of the screen displays the corrected RMS and PF after compensation by the Sinexcel SVG. Note that the phase current imbalance has been corrected and the RMS has been reduced to 442A (approx. 17% reduction). The PF has been corrected to 0.995. This sort of performance cannot be achieved with traditional PFC systems.
By correcting the power factor and the phase imbalance, the Sinexcel SVG presented an almost perfect load to the grid, resulting in a maximum return available when a kVA peak demand tariff is used, which significantly reduced their energy costs.
For more information of SVG’s see the Australia Supplier Fuse Co

PFC unit installed at Haileybury Rendal School, Berrimah, NT

Power Factor Correction Capacitors?

A power factor correction capacitor (PFC capacitor) is a type of equipment that can help to improve the power factor of an electrical circuit.
For example, if there’s a lagging current within the circuit, it will require additional power from the supply. This is also the case if there’s a leading current within the circuit, where the voltage waveform is slightly behind the current waveform.
It is possible to balance the inductive load with the capacitive load which can then cancel out the extra power requirement from the supply.
A PFC capacitor will provide a leading current to help bring the measure closer to unity (power factor of 1). This is the point at which the voltage waveform and the current waveform are balanced.
The closer the measure is to unity, then the less power that is drawn from the supply. This reduces demand, which means less electrical generation is required.
An electrical circuit is a circular path that allows electricity to flow. This network is closed, enabling a return path for the current. The process of improving the power factor of an electrical circuit is called power factor correction (PFC).
One of the ways PFC is achieved is by adding a capacitor to a circuit alongside your switchgear. The capacitor stores energy in an electric field which can help to improve the efficiency of your electrical systems which in turn will reduce electricity costs.

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