Alma Products saves £80,000 pa on drives installation

Alma engineering manager David Green says that ABB motor service partner Quantum Controls examined its extruders' energy usage before recommending the plant upgrade, with financial assistance from the Carbon Trust. The extruders were running on a dc drive system, he explains, which took load whether required or not, since dc motors draw current even while producing zero torque. He also states that maintenance costs for the dc motors were becoming an issue. Green says Quantum offered a hire trial to prove projected savings, with one of the dc systems being monitored for two weeks (using a three-phase energy data logger), before fitting a temporary ABB 132kW ac drive and 132kW motor for a further two weeks. That demonstrated a greater than 25% energy saving, backing up the estimated total of over £80,000, if all four main extrusion lines were converted to ac drive technology. Following the tests, Quantum was awarded the contract to fit the motors and drives, with the project funded by a £100,000 loan from the Carbon Trust. "Quantum was extremely helpful. They wrote the application for the Carbon Trust loan to suit our requirements [and] we were very pleased with their performance," comments Green, adding that he expects a two-year payback. Now, he explains, the drives are fed from 4—20mA signals from pressure transducers before and after the extruder pump, to enable speed control and correct back pressure for material feed control. "There is another potential benefit of the drives installation, in that it gives us more information on what is happening with the process," comments Green. "In time, this will help us calculate throughput and gives us a better idea of the load the machine is handling and how efficiently we are making use of its production capacity," he explains.