16 November 2007, News release from powerPerfector
First covered in Energy World January 2006, voltage power optimisation is getting more popular - as Angus Robertson of powerPerfector writes.
Voltage power optimisation (VPO) has been proven to be several times more effective than simple voltage reduction in saving energy and, since the technology arrived on these shores four years ago, VPO has allowed the commercial, industrial and public sectors to reduce their electrical energy consumption by an average 13% in the several hundred sites where it has been installed. To date this single technology has saved over 50 million kWh and 21,000 tonnes of carbon emissions, simply by allowing electrical equipment to work at much higher efficiency levels after the power supply to the buildings has been optimised.
The need to optimise
Following European harmonisation in 1995, the declared electricity supply in the UK became 230 V nominal, +10% to -6%, so supply voltage can be anywhere between 216 V and 253 V depending on local conditions. Most electrical equipment, designed to work for the whole European market, has an optimum operating level of 220 V, as this was the nominal supply level prior to 1995. Yet, in practice over 90% of sites in the UK continue to receive voltage at the historic average level of 242 V - and will continue to do so because of the design of the infrastructure.
The macro infrastructure of the grid cannot be changed and the physics of 'volt drop' does not allow the utility companies to tap down their HV transformers and micro-manage supply levels to their customers. For this reason, we are routinely supplying our equipment at over 20 V higher than its (near) optimum supply level, and this excess wastes huge amounts of energy.
The great advantage of VPO technology is that it ensures that all the electrical equipment on a site delivers close to its rated power, without the waste that over-voltage causes, and it is surprisingly easy to fit. VPO technology is now being installed on both LV supplies (415 V) and at larger sites where HV is supplied (11,000 V) and transformed to LV.
However, simply reducing voltage with an HV tap down (if you own your HV/LV transformer) does not have the same effect and, if you do it, you are simply wasting an opportunity. The proof of this is in the fact that companies (Tesco Ireland, Hilton Hotels) are actually tapping up their HV transformers and carrying out a larger step-down with a VPO unit, as this approach makes for a more efficient supply and increases savings.
Firstly, VPO has remarkably low losses of 0.1% throughout its operating range - that is to say it is 99.9% efficient, so does not generate heat like with a conventional transformer. The reasons for this are in its innovative design and construction, which avoid the dual-wound configuration of a voltage transformer.
The supply voltage to the building is optimised through a compound magnetic interaction, which uniquely integrates the ability to simultaneously correct and improve the power quality to an entire site. Suppressing the harmonics and improving the balance of the three-phase voltage supply allows equipment to run closer to its optimum operation level, thereby reducing losses and consumption in three-phase equipment such as air conditioning, ventilation, refrigeration equipment and pumps. If you supply a motor with a 5% imbalance in three-phase supply it will draw approximately 20% more power.
It is worth mentioning here that, if you supply a 230 V rated bulb with 240 V it will only achieve 55% of its expected life. This illustrates that VPO actually reduces capital spend on equipment as well as maintenance costs.
It has to be understood that supplied power in the UK is not as clean and pure as we would like, and is also deteriorating as the increasing use of small-scale generating plants, including wind generation, gives rise to more switching on the grid - and hence more harmful transients. (Transients are short-term high voltage spikes that can damage electronics.) VPO technology has the ability to buffer and eliminate these up to 25,000 V. Harmonic distortion from nonlinear loads is also reducing power quality as more IT equipment comes online. To combat this, the government introduced the G5/4 guidelines in 2003 that require both utility companies and customers to limit their harmonic outputs. So, by filtering harmful harmonics from the supply, VPO is able both to protect sensitive equipment and provide it with a clean power supply.
Figure 1. Energy savings at Wycombe County Council Town Hall
VPO is effective for almost any site with an electrical load and organisations of all sizes and types have been installing the technology. Early adopters included printing firms such as Buxton Press, who noted reduced noise levels on their print floor by optimising their supply, as well as reducing their electricity bills by over 13%. Land Registry (the largest property database in the UK) and over 40 councils and local authorities throughout the country have been selecting the technology for offices, town halls, leisure centres, schools and civic buildings of all kinds, in their commitment to reduce their carbon emissions and costs. As an example, Wycombe County Council have proven savings of 22% after the installation of the technology (see Figure 1), although the average is saving level is 13-14% over all sites.
The largest (2 MVA) VPO unit in the UK has been installed at Trelleborg IAVS, a manufacturer of automotive parts in Leicester, demonstrating the technology's application in heavy manufacturing, with savings of over 12%.
As the government body responsible for environmental matters, the decision by DEFRA to roll-out VPO technology across its sites around the UK is hugely significant. Successful trials have taken place at Kings House, Reading, and the Rural Payments Agency in Newcastle. The two sites have savings of over 13%.
For further information please email powerPerfector