Controlling voltage to control costs

Voltage optimisation (VO) can help companies cut both costs and emissions, as Jeremy Dodge, business manager at Marshall-Tufflex, explains

Rising power bills and toughened environmental legislation are forcing UK manufacturing and industrial plants to implement energy-saving regimes, with voltage optimisation one of the more straight-forward technologies to adopt, as demonstrated by two manufacturing sites in the south of England.

Littlewood Fencing, a specialist barrier and fencing producer, saw almost immediate results after investing in a VO system, reducing its power use by approximately 25% in the first five months post installation.

Not only did that equate to an average monthly power saving of more than 4000kWh, with maximum load reduced by more than 11%, it delivered another benefit, as a company spokesman explained: "Increasingly clients, especially those working on large public and private sector contracts, want to know what steps our business - as their potential supply partner - has taken to improve its environmental performance. It is an increasingly important part of the specification process and the installation of the VO system is a clear demonstration of our commitment to environmental excellence." So, not only is the VO system reducing the company's CO2 emissions by approximately 40,000t per year and cutting its electricity bills by up to 20%, it has boosted Littlewood Fencing's environmental credentials, providing an additional competitive edge when tendering for business.

Swimming pool manufacturer Plastica has also benefited from VO, reducing its power bills by approximately £12,000 per year, allowing it to recoup its investment within a year. The voltage optimisation system designed for Plastica was built on-site and installed over several days. Final commissioning required the site to power down and was therefore planned for a weekend in order to minimise disruption to the manufacturing plant and company offices.

Both Littlewoods Fencing and Plastica opted for the Voltis power saving system from Marshall-Tufflex Energy Management.

There are a number of VO systems available in the UK - Voltis is one of a new-breed of systems with 'logic-controlled' intelligence.

This means it constantly monitors incoming mains voltage supply and the power demand of the site, adjusting itself automatically to maximise efficiency, with power and carbon savings of 15 to 20% achievable. Constant monitoring also allows the system to automatically switch to stand-by if mains supply dips too low, safeguarding power to site. This is achieved through a neutral switching method so there is no break in the power supply to site - the switch from save mode to mains mode is seamless. This is a more modern approach compared with employing a more basic 'step down' technology which reduces mains voltage by a fixed ratio and may cut power to site if mains supply dips too low.Most older-style systems generally return savings of around 8 to12%.

Why does VO work? Why VO works is simple: The UK's electricity supply is set at a nominal 230V (+10% to -6%). Therefore power supplied by the National Grid can vary from around 216V to 253V but averages about 240V.

Equipment is designed to work most efficiently at around 220V. Over-voltage dissipates as heat and vibration within machinery/equipment, reducing its operational life (research suggests that an over supply in voltage of 10% - ie 220V to 242V - can reduce the life of electrical/electronic equipment by up to 90%). VO systems are installed in series with mains electricity, reducing the voltage of electricity fed to equipment and machinery, for example from 242V to around 220V.

Electricity bills are reduced, carbon emissions lowered and the life-span of electrical equipment increased.

Select the right VO system and it will also reduce maximum demand levels, refine power quality by balancing the phases on three phase supply, reduce harmonic distortion (this is particularly the case of three phase systems using single phase auto transformers), suppress transients and improve power factor correction.

When considering voltage optimisation it is imperative to understand how each of the systems works and to research the market, asking questions and requesting proof of fuel bill savings. Check other energy saving methods installed at the same time as the VO system, for example low energy light bulbs and movement sensors, and ensure savings figures are produced separately for each energy saving element. Also take care if developments are planned for your site - mains supply levels may drop if new facilities are added to the existing power supply. Therefore your incoming voltage level could drop naturally, which if you have a fixed ratio solution in place could create problems.