Variable speed drives help regulate energy consumption

20 November 2014

Emerson Industrial Automation is supplying Powerdrive MD2 variable speed drives to help regulate the energy consumption of a central fume aspiration system within an industrial foundry.

Zanardi Fonderie S.p.A produces spheroidal graphite castings. The company needed to find a solution to ensure it was able to maintain a balance between quality and flexibility and competitive running costs.
The company’s corporate strategy is aimed at optimising its manufacturing system’s efficiency, in particular with a view to improving energy efficiency. To implement this, Zanardi approached G.B.M. S.p.A. of Milan, a commercial company with a long tradition as a supplier within foundries industry.  In turn G.B.M. called on the help of Emerson Industrial Automation Italy S.p.A. 

G.B.M began by looking at the possibility of reducing the energy consumption within Zanardi’s central fume aspiration system; a process that consumes an enormous amount of energy but is essential to protecting the health of the factory operators.
Energy experts from Emerson Industrial Automation, working in collaboration with Massimo Ceschel, production director at Zanardi, collected data to provide a clear picture of how the equipment operates as well as any requirements in terms of finance and performance. Their aim was to regulate the flow of the aspiration system while reducing electricity consumption. 

Engineer Alessandro Zanardi, technical manager of Zanardi, provided Emerson's technicians with a huge amount of data on the system’s consumption rates, the flows required in order to keep the system working properly throughout all stages of manufacture, even down to details regarding the system's annual working hours. The technicians also looked into problems relating to the use of sensors to regulate differential pressure, which resulted in a recommendation that no ‘vulnerable’ instruments should be allowed to operate in a hot environment where abrasive powders are present.
Based on the data collected, several scenarios were put forward, aimed at adapting the equipment's flow to the individual requirements at each stage of the aspiration system. Defining a simple and efficient technical solution, Emerson proposed to replace the current motor with an upgraded AC motor and control it using a Powerdrive MD2 variable speed drive. The idea was put forward, together with a detailed technical and financial report setting out an amortisation period of less than two years. This plan was constructed without taking into consideration the possibility of a European Commission’s white Energy Efficiency certificates that could be awarded after implementation.
After being presented with the proposal, Zanardi’s engineer called in the system integrator responsible for automating the process to establish a method of interfacing with the drive in order to regulate the ventilator's outflow. A PLC and a synoptic display on a PC, communicated with the drive over Profibus, to adapt the flow reference to the various phases set by the PLC.
The project aimed at updating the drive system in parallel with the existing electromechanical start-up; this also makes it possible to use the old system as emergency by-pass for the new Powerdrive MD2 drive cabinet.
The Powerdrive MD2 cabinet has been set up close to the Leroy Somer motor, which smoothly replaced its predecessor during a several-day scheduled break in production.
The recording of post-implementation energy consumption started after the system was commissioned. The system has responded well from an operational viewpoint and there has been no negative effect on the system's aspiration capacity.
Today, the ventilator consumes less than 1200 kWh/day on average compared with previous consumption of 2000 kWh/day resulting in a 40% saving on electricity costs. Compared with the overall costs involved in the operation, the saving achieved results in an amortisation period of less than the predicted two years under current manufacturing conditions.
On top of all of this the project has been awarded a type 1 Energy Efficiency Certificate based on the significant realised figures, which decrease the amortisation period to less than a year.

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