Aregger Engineering AG (Aregger) provides engineering services in the field of open-loop and closed-loop control technology. The focus is on complex control tasks, primarily for the dairy and mixed feed industry. When commissioned to modernize the grain silo at Kohler AG in Lüsslingen, Switzerland, which has a capacity of 10,000 metric tons, in order to keep the wiring effort to a minimum and to make troubleshooting as easy as possible in the event of an error, Aregger used control technology from Siemens for the project. This solution offers precise system diagnostics, which increases availability. In addition, with compact Siemens components, Aregger was able to reduce the control cabinet size and minimize the wiring effort.
A major challenge when modernizing this enormous silo with 79 cells was wiring the numerous pneumatic slide gates and flaps, which are fitted in a confined space. In addition, troubleshooting in the event of machine failure was difficult due to the limited diagnostics capabilities of the system used previously and the space required, particularly for the control cabinet, had to be reduced. In order to keep future wiring effort to a minimum, Aregger chose the Simatic ET 200AL distributed I/O system from Siemens. This small and light modular I/O system has IP65/67 protection (protection against the ingress of foreign bodies such as dust and water) and can therefore be flexibly mounted outside the control cabinet directly next to the elements to be switched. The flexible mounting options of the Simatic ET 200AL reduce wiring costs by 15 percent and simplify the mounting process. The Simatic ET 200AL can be connected directly to the Simatic ET 200SP peripheral system installed in the control cabinet. The small footprint of the Simatic ET 200SP system saved a lot of space in the control cabinet. Therefore, an S7-1500 controller in the Simatic ET 200SP design was also selected as the controller. Thanks to the detailed diagnostic functions of the peripheral modules and Sinamics G120C PN drives used, the availability of the system has been increased. Due to the integrated diagnostic concept of the S7-1500, no programming effort is required. Pending messages are automatically displayed on the built-in SIPLUS KTP400 operating panel,
which has an additional coating on the electronic components, making it immune to condensation water and thus suitable for use even in the event of extreme temperature fluctuations, thus further increasing availability.