Voltage Optimsation Explained

BG re sized VO explained

Most plant engineers and facilities managers have heard of voltage optimisation (VO), but few are aware that this technology has taken giant leaps forward in recent times. The following guide provides answers to the most commonly asked questions concerning VO.

What is VO?

VO is technology that offers the capability to optimise the incoming mains voltage, typically by reducing, but sometimes by increasing it.

Why use VO?

There are lots of reason to adopt VO. For instance, over-voltage consumes more energy, leading to higher bills, and increases carbon footprint. Furthermore, voltage peaks and troughs can damage plant equipment, prompting higher costs in terms of maintenance, repair or replacement.

Peaks and troughs?

The UK suffers from over-voltage most of time, with supply from the National Grid hitting peaks of 253V. However, under-voltage can also occur, dipping to 202V in some instances. On average, voltage coming in from the National Grid is 242V, whereas most electrical equipment is designed to operate most effectively at 220V.

Will there always be peaks and troughs?

Yes, in fact volatility is only set to increase as the maximum power availability from the National Grid is reached, and as the Grid reacts to feed-in supplies from wind power, photovoltaic technologies and local generation, thus worsening power quality issues.

What’s the problem with basic VO?

Basic VO systems are based on simple step-down transformers which reduce the mains voltage by a fixed percentage, typically usually 4% or 6%. Though offering small savings, these old, fixed ratio style VO systems do not maximise the savings possible or resolve the problems caused by fluctuating voltages, which can damage sensitive electrical equipment. What’s more, conventional VO systems do not handle under-voltage very well. Here, the system will either deliver too low a voltage, resulting in serious on-site problems, or switch to bypass (to protect itself and the building’s supply), thus offering no savings whatsoever.

What is the latest VO technology?

voVoltage optimisation plus regulation equipment, known as eVO+R™, takes fluctuating incoming voltages and stabilises them to give a clean, consistent output voltage. This is usually set at the optimal 220V and ensures continuity of supply. The secret behind the success of eVO+R™ is its unique ‘Buck and Boost’ technology, which maintains the outgoing voltage at the optimum level whatever the incoming mains voltage.

How does Buck and Boost work?

Buck & Boost controls the voltage via a multiple tap transformer, and no other system on the UK market can offer this. The simple reality is that the National Grid voltage fluctuates continuously and most sites will suffer from at least a 12V swing. Fluctuations in the incoming supply voltages limit the ability of basic fixed ration VO to deliver savings.

What are the main benefits of eVO+R™?

eVO+R™, with its Buck and Boost technology, can generate savings up to a staggering 30% greater than conventional VO systems, not only reducing bills but maximising ROI. Carbon emissions are also reduced, making it ideal technology for those participating in the CRC energy efficiency scheme. Moreover, eVO+R™ gives electrical infrastructure and equipment total protection against over-voltage and under-voltage from the National Grid. A regulated and managed voltage can resolve plant, machinery and electrical problems caused by brown-outs and voltage spikes.

Does the voltage have to be optimised at 220V?

Although 220V is the optimum setting for most commercial electricity users, eVO+R™ technology allows the voltage to be varied on-load in 1V increments (thus providing guaranteed future-proofing), to match the particular characteristics of a site, such as those with critical loads for example. Each system can be fine-tuned to ensure savings are maximised. Indeed, each phase can be stabilised independently. This improves overall power quality, reduces harmonics, and extends the life expectancy of electrical equipment to reduce maintenance costs.

Where is eVO+R™ used?

eVO+R™ technology is installed throughout Europe at facilities including industrial sites, hotels, hospitals, shopping centres, cinemas, education establishments, fire stations, rescue centres, government departments and many more besides. eVO+R™ systems are designed for all types of commercial and industrial sites with sensitive and mission critical loads from under 100Kva to over 3,500Kva.

Is it expensive?

No. In fact, it is even possible to obtain a lease rental purchase. This option is typically over a three or four year period, which often allows the eVO+R™ system to be funded from the savings generated by reduced electricity usage. In short, no capital expenditure is required.

How long does installation take, and can it be done out of hours?

This will vary according to the specific requirements of each individual site. A good supplier will work with the customer to ensure equipment downtime is limited to only what’s necessary, and ensure that the work is carried out at a time convenient to the customer, for example, out of hours if requested.

What is the lifetime of a voltage optimiser?

As with all equipment, the lifetime of an optimiser depends on its use and treatment over time. Provided the equipment is used and maintained in the right way you can expect a very long service life – of at least 20 years.

Does this technology come recommended?

The use of VO management technologies is advocated by the Carbon Trust in its Voltage Management Guide CTG045 as a means of providing the best foundation for carbon reduction activities. Indeed, a comprehensive approach to the reduction of carbon emissions should in all cases begin with the incoming electricity supply.

What does CTG045 say?

The Carbon Trust’s CTG045 explains the benefits of VO, how it works, and prescribes a methodology on how site surveys should be conducted. This has developed a minimum standard for the industry and helped end users understand what VO is all about and how it is applicable to their needs.

What does a site survey entail?

A site survey and energy audit entails more than just plugging in a simple voltage logger and using kWh data. A detailed site survey needs to be conducted, including a week long evaluation of the mains voltage and load profile, in order to determine the correct system size and deliver an honest appraisal of the potential for savings. In addition, a unit by unit evaluation of all the equipment on site is required as savings are only available from electrical equipment that is voltage dependent – and not from equipment that is voltage independent.

Voltage dependent?

In simplistic terms, voltage dependent devices consume power proportional to the supply voltage – the higher the voltage the higher the power consumption – and if the voltage is reduced, less electricity will be used. A 1% decrease in supply voltage will cause a 2% reduction in power demand, thus saving money.

What are example of voltage dependent and independent equipment?

Examples of voltage dependent devices would be incandescent lamps, T8 & T12 type fluorescent Lamps, many motors and air conditioning units. Voltage Independent devices however, are designed to consume energy regardless of the supply voltage, and with these savings are not possible. Examples would be T5 and LED lighting, ICT equipment and VSDs. All of this can be determined at site survey stage.

Who should carry out a site survey?

It’s recommended that any potential customer requiring a site survey and energy audit should only use the services of a Carbon Trust accredited supplier.

Please visit our sister company e-fficient Energy Ltd, a power management solutions specialist – to find out more about our voltage optimisation technologies.