“The facility is not continuously in operation. The summer and winter mistletoe extracts are only processed into a healing extract twice a year,” states Schaller, explaining why Iscador AG had been able to live with the previous solution despite these limitations. The modernization of the existing installation, which was scheduled for 2017, specified that the new driving force behind the rotating disc should not have an impact on the network and should also be regenerative to conserve the environment.
Additional challenges had to be tackled as well: The actual facility entirely consists of custom products, in some cases without corresponding data, and may not be modified. Furthermore, only a very small window was available for trial runs.
Discussing the task at hand with Rockwell Automation, it turned out quickly that the pharmaceutical company in Arlesheim was looking for the performance delivered by an Allen-Bradley® PowerFlex® 755TR AC drive.
“We had this extraordinary application with custom-designed motors that could under no circumstances be damaged,” explains Invag’s Executive Manager. “The immense centrifugal forces demanded appropriate safety precautions. Seven sub-processes had to function both in a combined manner and independently. The centrifuge had to start up softly, brake in a controlled fashion and allow for the recovery of braking energy without interference,” he summarizes.
At Iscador, the AC drive – specifically a 200 kW IP21 model – functions as the central motor element for the production of the mistletoe drug. The motor control system must harmonize with the oil lubrication system on the engine mounting as well as the cooling unit and the pressurized air, vacuum and helium supply of the facility. The AC drive must adapt the rotational speed in accordance with the amount of helium available to flood the disc area. “At Iscador, we had six minutes to spin up to 10,000 rpm. Then the titanium disk had to rotate at constant speed for three hours, with thermal generation and vibrations simultaneously kept within a very limited range,” describes Martin Neuenschwander, Commercial Engineer at Rockwell Automation.