The company makes extensive use of air extraction systems. Until recently, the fans used in these systems were driven by motors with ordinary direct-on-line starters that provided no speed control.
However, to help improve energy efficiency and to minimise environmental impact, Whitford decided to take advantage of Ralspeed’s energy appraisal service, which examines drive applications and provides information about the energy savings that can be achieved by using the latest drive technology.
The information produced by the appraisal service was compelling. Each of the extract plant’s 7.5kW fan motors were running at full speed for 59 hours per week, 50 weeks of the year, consuming 18,800kWh of electricity per year at a cost of £1,540.
Ralspeed suggested fitting the fans with variable speed drives that would allow them to run at a speed optimally matched to the requirements of the manufacturing process. This would allow the annual consumption for each motor to be cut to around 6,500kWh and the energy cost to £528. The calculations also showed that the carbon footprint of each fan would be reduced from 8.09 tonnes of CO2 per year to just 2.78 tonnes.
"After seeing these figures, we decided to go ahead with the installation of variable speed drives, and that we should seek funding support from the Carbon Trust," said Des Griffiths, plant engineer for Whitford. "Ralspeed helped us to prepare and make our submission to the Carbon Trust and we secured an interest-free loan to cover the cost of the project."
To date, Ralspeed has converted five extract fans to variable speed operation with more planned in the future future. The conversion involved fitting a control panel designed and built by Ralspeed, which incorporates a Vacon NXL AC variable speed drive. Once the new drive systems had been installed, it quickly became apparent that they would not only reduce energy usage and costs, but would also provide other important benefits. For example, smooth controlled starting and stopping of the fans, as well as the lower running speed for much of the time, is minimising wear and tear on the drive belts and bearings, which will extend the life of the equipment and reduce maintenance requirements.