Guaranteeing process reliability

With the modernization of system parts, Unilever in Heppenheim is aiming for greater process reliability and energy savings at the same time. With the help of the Wago-I/O-System, the company replaced the hardware controllers with a software controller.


In seven locations, Unilever Deutschland GmbH produces foods such as ice cream, prepared dishes, and margarine. One of the locations is the Unilever Deutschland Produktions GmbH & Co OHG plant in Heppenheim, the largest Unilever ice cream factory in the world. From Heppenheim, the company supplies all of Europe with Magnum, Capri, Cremissimo, Viennetta, and other ice cream brands. The company‘s strengths include the top quality of its products, competitive costs, and the necessary flexibility within the company. With 770 employees, the plant can produce up to 170 million liters of ice cream each year. In the high season, more than 1500 pallets with ice cream packages leave the four production halls each day – when stacked one atop another, this quantity would be as high as the icy peak of the Zugspitze.

System availability on the test bench
For warming or cooling of ingredients to be added such as chocolate, the Mixing Department relies on portable tempering devices with hardware controllers and contactors. However, no more spare parts are available for these devices, something that endangers process reliability in the long term. Every contactor in the tempering devices runs through approximately 100,000 operating cycles each year. With this load, they would quickly approach their theoretical wear limit. “The old hardware controllers represent a black box without any documentation or alarming in case of breakdown,” adds Thomas Held, Team Director for Electrical Maintenance and System Administrator AT/IT in the Mixing Department at Unilever in Heppenheim. At the end of last year, the starting shot for the remodeling of the tempering devices was heard, whereby the existing infrastructure was supposed to be retained and a coupling to the process control system enabled.

New automation solution saves space
The people responsible in the Mixing Department selected the Wago-I/O-System with the 750-871 Ethernet controller as the controller. Thanks to its small dimensions and modular construction, the new controller fit easily into the available installation space in the tempering device. The individually combinable digital input/output modules as well as the analog input/output modules of the system are replacing the old switching devices and nevertheless leaving sufficient space for expansions. With the Ethernet interfaces integrated into the controller, the tempering device can be integrated easily into the Mixing Department‘s automation concept. Thus, the tempering devices no longer function as “islands”; instead, they make the process data available to the superior control system via OPC servers. Furthermore, alarm management could be integrated into the controller via e-mail; it monitors errors and limit values and thus contributes to process reliability.

On the trail of energy consumption
Thanks to the modernization of the tempering devices, it is now pos¬sible to record energy data using the Wago-I/O-System. The bus modules arranged on the I/O system record signals from flow meters, temperature sensors, and electricity meters; the PLC calculates the output data on the basis of these. “Thanks to the use of the controllers, our flexibility increased with respect to the utilization of the systems and also the fine-tuning of the tempering. For example, due to the optimization in the control circuits, the energy costs for the tempering devices could be reduced drastically,” adds System Administrator Thomas Held.

Programmability scores points during selection
The people responsible weighed both the technical and economic aspects before making the final decision in favor of one system. For the use of the Wago-I/O-System, the investments required were only approximately one-third of those for comparable systems from other manufacturers. Thanks to the programmability according to IEC 6113103 with CoDeSys, all control parameters for the temperature sensor, error monitoring, and limit value settings could be optimized easily. In the course of the modernization, the tempering device got a 5.7” Web panel from the Perspecto product family and a visualization with input screen for the controller, limit, and target values, as well as for the on-site display of actual values, errors, alarms, and limit value violations.