powerPerfector a Voltage Power Optimisation Technology

The powerPerfector[1] is another form of power quality products. A power quality product aims to improve the voltage waveform of an apparatus so that it can work more efficiently.

powerPerfector claims to reduce energy losses by:

Suppressing harmonics.
Improving the power factor of your electricity supply.
Eliminating transients.

As a result of improving the voltage waveform, the powerPerfector claims to:

Reduce your energy usage by up to 20%
Reduce Carbon emissions by up to 20%
Reduce your maximum demand by 15%
Reduce reactive power by up to 45%

This in turn means that your equipment will work more efficiently, and therefore lasts longer. Equipment is protected from transients, and the powerPerfector lowers the operating temperature of the apparatus.

Please read the ‘Background to the grid and voltage waveform situation’ section of the article to understand the terms used above.

A case study titled ‘Sustainable Development in Government Report’ was written by DEFRA estates in 2007 [2]. They say that after ‘researching innovative technologies’ that focused on ‘improving energy efficiency and carbon emissions’, powerPerfector was identified as a ‘Voltage Optimisation’ technology that ‘had the potential to deliver the largest energy efficiency and emissions reductions – than any other technology currently available’. A pilot installation programme was undertaken using energy, emissions and cost data for 5 estates. The funding needed for the 5 sites, ’10 powerPerfector units’ equated to ‘£582,000’, with a payback period of ’28 months and energy efficiencies between 8% and 11%’. [2]

The question is: is it worth installing a powerPerfector unit? Do you really need to install voltage optimisation technologies when there may be better and cheaper alternatives that could meet you emission reduction targets? As with the case study above, they ascertained that they really did need it as it would deliver the largest reduction in emissions. This would indicate that the pilot projects were in areas where the voltage was indeed higher than it ought to be, by installing powerPerfector units this would reduce it. The case study goes on to say that powerPerfector addressed compatibility issues, and so one can assume that they completed detailed reports and concluded that reductions/energy efficiency could be between 8% and 11%.

The Carbon Trust [3] offer an interest free loan repayable over up to 4 years with no application fee. The loan can be worth between £5,000 and £200,000. This is available to any sized company providing its annual electricity bill is below £500,000.

From reading various blogs, it has thrown up some good and bad experiences for people that are briefly outlined below [4]:

Two powerPerfector had been installed at schools. There was no issue with the actual mechanics of the powerPerfector; however, the powerPerfector had caused them to experience 204V at the end of some distribution circuits. This resulted in loss of server equipment and possible loss of shock protection. The person believes that the product is designed for resistive and reactance being constant.
In another message, a different person found that they had a very aggressive sales pitch which resulted in three installations. According to them, none of them had made any savings, and two had been taken out of service. Despite this, there still remains the belief that the product is not to blame, but should be more suited to supermarkets where they have large amounts of freezers.
Another person’s comments reported that they had between 8% and 20% savings in their schools and colleges. With no reduction in lux levels. However, they do state that a careful feasibility study is required to ensure savings are met.
Another person believes they have identified a problem after clarification with other companies and university professors (not stated) that the product will only work with certain loads, being mainly inductive.

Some points to think about:

Is it necessary to have one or are there other means in reducing you energy consumption? It will depend on the quality of supply in your area and the sensitivity of your equipment.
Is the power quality in your area good? If so, then you shouldn’t need one.
Domestic power demand is likely to become more volatile than regional and national.

So:

If each house implements demand management, theoretically the demand SHOULD be less volatile than at present or possibly in the near future.
Little research has been done on domestic power factor correction.
The voltage supply should not exceed the +10% limit that supply companies sell electricity to you as you can sue them for this! So, any fabrication that your voltage supply is higher than it should be should be taken with a pinch of salt, or investigated.

Background to the Grid and Voltage Waveform Situation

It is important to understand the basic principles of the UK grid system. The grid works on three levels: Generation, Transmission and Distribution. The generation level ‘supplies’ the grid with electricity. The transmission level carries the electricity from generation to distribution levels. The National Grid balances the supply and demand of the transmission grid. The distribution level carries/supplies the electricity to the consumer. The consumer is the ‘demand’. Energy companies supply you with electricity at the distribution level. But they can also be the generator.

Electrical energy is transported through the grid by a three-phase supply, because of economical reasons. The three phase supply is generally used by big buildings or industrial premises that require a large voltage to run heavy machinery. The three-phase supply voltage is supposed to be supplied at 415V. The regulations allow a -10% and +10% margin around 400V. So the voltage can be supplied to the consumer anywhere between 360V and 440V. At a domestic level (dwellings, small offices etc) the supply voltage is single phase and is supposed to be supplied to you at 230V. Again there is a -10% and +10% margin around this, meaning that a voltage can be supplied to the consumer anywhere between 207V and 253V.

The main problems are:

The UK has an average voltage supply of 242V. Compared with the European, which is 220V.
Most appliances are manufactured in Europe, which are built for a 230V supply.
It is ‘over voltage’ that reduces the appliances lifespan and uses un-required electrical energy.

The voltage is the force that drives current through electrical equipment. If the voltage is too low, the equipment under-performs. If the voltage is too high, it over-performs and fails.

Explanations of Terms

Voltage Waveform

A mathematical representation of a voltages characteristic in the form of a graph. The voltage is depicted as a wave alternating between positive and negative values over a period of time. The difference between these two values is known as the amplitude.

Reactive Power

In a normal AC (Alternating Current) circuit, where there is a source (generator) and a user of the electricity (load), the current and voltage follow a sinusoidal nature (the shape of the graph above). Whether the user is using the electricity or not (taking or resisting), the current and voltage ‘flows’ in the same direction. This is known as ‘real power’.

Reactance is an opposition to the flow of an AC current, like resistance, but is actually caused by inductance and capacitance. Reactance can flow in either direction (just like AC) as well as occurring in short spells when direct current (DC) changes, i.e. when something is turned off.

To extend this idea, imagine that the load (user) is completely reactive. The voltage and current flows are completely out of phase/not in line with each other. This produces a reactive flow, meaning there is no flow of electricity to the load (user). (See graph below)

So, real power transfers ‘actual’ electrical energy, and reactive power does not transfer ‘useful’ electrical energy. Reactive power is a problem, even though it transfers no electricity, it heats wires –wasting energy.

Power Factor

The Power Factor of an AC current is the ratio of real (true) power to apparent power. Apparent power (in the case of a true resistive circuit) is the power you are getting out, the same as real power. Real power is the measure of the capacity for a circuit to work at a given time. Apparent power is the product of current and voltage. Apparent and real powers are two different things. If reactance exists, then apparent power is bigger than true power.

A user with a low power factor draws more current than a user with a high power factor.

Why is the power factor important? Because the power factor is measured in volt/amps and energy suppliers charge you for the amount of watts you use. If you have a low power factor, you are being charged for not only useful electrical energy (real power) but also electrical energy that you haven’t physically used in your machinery because it is in the form of reactive/apparent power!

Harmonics

Harmonics are affected voltages and currents resulting from certain electrical loads on the grid. Harmonics cause power quality problems. In an AC system in the UK, the voltage travels at a frequency of 50Hz (Hertz) +/-0.5Hz. When an electrical load is connected to this system, it travels at the same frequency, but not within the same phase. This phase difference will need to be cancelled out or rectified. (See graph below)

Transients

A ‘transient’ is a sudden quick spike or dip in the grid voltage of an electrical system, often associated with grid faults (for example, balanced or unbalanced three phase faults). One particular cause is a lightning strike on the gird!

Operating Temperature and Heat Loss

Due to reactance within a system, an apparatus or machine is forced more voltage and current than it actually requires. This electrical energy has to be dissipated somewhere, usually in the form of heat. If a machine is not purpose built to allow for extra electrical energy than it is supplied with, its lifespan is reduced.

Three Phase and Single Phase

Remember, when a polarity of a current changes between + and -, this generates an alternating current. One cycle from zero, to +ve, back through zero to –ve and finally back to zero again is called a ‘phase’ (similar to the first graph). So, one of these phases in one wire is known as ‘single phase’. Now, add two other wires to the generator, so that all three are in a particular position separate from each other, and switch on the generator. Three separate phases will now travel through 3 different wires. As the positioning of the three wires is separate from each other, the three phases will travel at different times.

As an application, three phase is regarded as a smoother and more powerful supply of electrical energy than single phase, yet it is also more expensive than single phase. As a result of this, three phase is generally used for large scale buildings and machinery, and single phase for small (low demand) dwellings.

1. Power Perfector Website. www.powerperfector.com

2. DEFRA 2007 Case Study. Available [Online]: http://www.edie.net/news/news_story.asp?id=14393

4. IET Forum, topic –Power Perfector. Page 4. Available [Online]: http://www.theiet.org/forums/forum/messageview.cfm?catid=226&threadid=22879&STARTPAGE=4&FTVAR_FORUMVIEWTMP=Linear