For the end customer, saving is not just saving: Güntner AG & Co. KG has offered power-saving EC fans from ebm-papst in its equipment since 2006 as an alternative to AC fans. The principal argument at the time was the greater energy efficiency. But it took until 2008 before the offer was as well received on the market as the globally leading company in heat transfer technology had envisaged. Güntner researched the reasons for the market reluctance and decided to revise the concept and to integrate ebm-papst.
A good approach
“Güntner recognised that the opportunities provided by EC fans were not being optimally exploited by the customers,” recalls the Mulfingen project engineer Martin Schulz. The Fürstenfeldbruck-based company took a complete line of EC axial fans from ebm-papst ranging from 500 to 910 millimetres in diameter. Depending on the application, the fans were programmed to a certain speed by ebm-papst. This created one-to-one replacement models for the AC fans that had been exclusively used until then. The equipment thus uses less energy and offers long-term savings, even though initial investment costs are higher at first sight. But because the power electronics are already integrated into the EC fans, the customer also saves cost of the control box.
For Güntner, the advantage was being able to use a versatile motor in different units. However, that meant that the fans had to be programmed differently for each model. The EC fans were eminently suitable for this as they have an extensive interface that the end customer is able to use. “That was the crucial point,” remembers Jörg Köcher, head of Güntner Controls. “Customers do not want to do the programming themselves, they want to buy a working heat exchanger that is perfectly configured for noise and performance.” on this basis, Güntner revised the entire concept with respect to usability.
Plug and play
The technical challenges were the bus system, the automatic setting of the operating points and thus the plug-and-play capability. “We wanted the units to work like a new printer – plug them in and they connect up themselves,” Köcher explains the plan. “That caused us real trouble. How should a fan connect itself up without first being assigned a bus address, and what happens if two fans have the same address?” Güntner resolved this problem by developing a controller that performs all technical refrigeration control functions and which offers exactly this plug-and-play capability. To this end, a bus system is used to provide the information in the fan and to make this usable for the control system. Data that is important for the settings of the heat exchanger is still written to the fans. The requirements of the fans were discussed. “Initially, it really was a struggle, until we agreed on the concept side,” says Köcher of the coordination process, which wasn’t always plain sailing, but which ultimately produced a successful solution. “Each company concentrated on its core competence. Güntner on the heat exchanger side. ebm-papst on the motors and the fluid mechanics.”
“A new line of EC fans with a diameter ranging from 450 to 990 millimetres and with bus communication was specially developed for and with Güntner and these fans were aerodynamically adapted to Güntner vents – and all that was done in a required development time of 12 months,” explains Martin Schulz, summarising the development requirements.
With these marginal conditions, the engineers at Mulfingen started identifying 26 motor/electronics/impeller combinations and assigning each of them to the operating ranges. The complete series was equipped with energy-efficient EC motors using the very latest HyBlade® fan technology. Once the Mulfingen engineers had developed the electronics, they constructed the fan types as prototypes. Air performance and acoustic capacity in the Güntner vents were measured in the multipurpose measuring chamber. “This allowed us to provide Güntner with exact measured data for the fans in their applications,” reports Schulz.
The Güntner Motor Management (GMM) system was developed at Fürstenfeldbruck in parallel to the fan development at ebm-papst. This control system performs the technical regulation functions, the programming and the data evaluation of the EC fans in the refrigeration cycle. Within this closed loop, the fans act as actuators, ensuring that heat is dissipated via the heat exchanger. Communication via a bus system gives the GMM detailed information that helps to make the control system more precise and more user-friendly. Because the controller knows the characteristic curves in the fans, it knows which response it can expect in the closed loop even as it actuates. The controller is still able to make use of speed, electric power, current draw, operating status, error messages and many more items of data from the fans. These are all additional benefits that goes to enhance the information content and thus increase the operating reliability of the system. Moreover, the controller also checks the fan type, regardless of whether it is a new unit or, in a service case, one that has been installed for a number of years. In either case, the GMM will automatically assume the task of programming. “The problem with the old solution was that absolutely no visualisation was possible. It was like taking the display off of a microwave. We were unable to change any values, we couldn’t see which operating state the control system was working in, we simply couldn’t see what was happening inside,” explains Jörg Köcher. Apart from more straightforward controls, the precisely configured functions mean all in all considerable savings are possible for commissioning and for running costs.
One of the main advantages of the intelligent control system is its optimal energy management. At all times, the fan will only deliver exactly the air volume that is actually required. “In combination with the already extremely energy-efficient EC technology, a package can be offered that cannot be beaten in terms of energy efficiency,” stresses Schulz. And Köcher adds: “Our advantages are our customers’ advantages. We now offer energy-efficient, intelligent equipment with extended functions. Here, we have developed an innovative system that gives us the edge on the market. Moreover, the multiple use of the EC fans in different equipment means that our stock levels are much lower.” The success of the development partnership can also be seen in sales. Quantities have risen greatly since the launch in April.