The second largest lime producer in Europe, the Fels group - an enterprise of Preussag AG - puts its money on INTERBUS. Each year, Fels supplies more than two million tons of fat lime and over three million tons of lime stone products for a wide variety of areas of application. In addition, one of the main areas of business of the enterprise are Fermacell plaster fibre boards, aerated concrete sold under the name of Ytong, and Salith dry mortar systems.

History

In 1991, the Fels-Werke GmbH took over the former "VEB Harzer Kalk- und Zementwerke" (nationally-owned Harzer lime and cement plant), the largest lime-producing plant of the former GDR. The existing plants were old-fashioned and had to be technically overhauled in view of their economic efficiency and environmental compatibility. A task which had to be performed under great pressure. Therefore, time-consuming planning and complicated interfaces within the system would only have been in the way. Since time was so short, they decided on a bus solution which is open for different suppliers and at the same time offers optimum reliability. Interbus, the sensor/actuator bus in the field and in the switch cabinet.

All on one bus

From 1993 to 1999, approximately 39,000 signals were selected at the Rübeland, Elbingerode, Münchehof and Schraplau sites, which were then integrated in the serial data transmission via INTERBUS. Filling level sensors and pressure or differential pressure transducers have been integrated into the concept as smoothly as frequency converters, position sensors and weighing systems. No problem thanks to the wide spectrum of connection options available with Interbus. Finally, PHOENIX CONTACT motor switches round off the whole range of couplings to INTERBUS for distributed conveying technology.

On the pulse of the process

A rough operating atmosphere characterizes the conditions for remote I/O stations with INTERBUS-ST modules. Exposed to the vibrations on the platforms and to the changing weather conditions, this range of modules has proven its reliability in everyday applications for more than five years now. Furthermore, special conditions such as widely distributed external installations require special measures: TRABTECH modules from PHOENIX CONTACT offer protection against lightning and surge voltages. In addition, transmission distances of up to 3.5 km are safely bridged by means of glass fiber cables. Here, PHOENIX CONTACT FO converters ensure the trouble-free conversion from electrical to optical signal and vice versa. Conclusion: Lightning has no chance in a protected system.

Behind the scenes

You will find INTERBUS where you would hardly expect it. Between power contactors in the switch cabinet, the ST modules monitor and control the smooth controlling and acknowledging of power components. No need to mention that in these cases it is especially necessary to consider electromagnetic compatibility caused by switching operations. But with its high reliability of transmission and mature module electronics, INTERBUS can even resist the directly emitted interferences of neighboring power components. Compared with these critical applications, the use of buses behind the measuring panels is an easy task.

From the nerve fibers to the brain

If we are looking at how the bus is coupled to the control system, we come across two old acquaintances: The INTERBUS host controller board from PHOENIX CONTACT in the S5-115U-PLC, equipped with 944 or 945 CPUs. In this way, a PLC-based, distributed control system which is connected to the visualization level by means of Arcnet has been realized. In the control room, VisiWin is used as the graphical user and monitoring interface of the system. On and on it goes ...

For more than five years now, the Fels-Werke has been working with INTERBUS. During this time, the operator has seen that the bus has been working reliably since start-up, which was simple and quick thanks to the diagnostic functions. In short, a bus that you could rely on in the past - and will rely on in the future.