Rohrdorfer Group modernizes mill drive with Sinamics

By modernizing its gearless mill drive with the new Sinamics SL150 converter, cement manufacturer Rohrdorfer Group has increased the availability of its plant without the need to interrupt on-going production.

The world’s first ring motor from Siemens has been doing stalwart service for over 45 years at the cement works in Rohrdorf, Bavaria. In 2014 the Ro­hrdorfer Group, which operates the cement works and is a Europe-wide producer of construction materials, commissioned Siemens to update the cement mill’s drive systems and the motor’s vital air gap sensors.

Bespoke drive concept

The concept Siemens devised for the Rohrdorfer Group was tailored to the precise requirements of the cement works, and was designed to bring the facility right up-to-date with the very latest technological developments. During the conversion process, the previously used direct converter was replaced by a new Sinamics SL150 in an air-cooled version using the Sinamics DCM converter for excitation.

This concept allowed the components to be installed and partially commissioned in parallel to the day-to-day running of the mill. As a result, the actual switchover from the old to the new converter could be conveniently performed within regular maintenance downtime periods, without causing a single day’s loss of production.

“Everything worked so smoothly that the conversion process was completed without me noticing much at all”, recalls Anton Bartinger, Technical Director of the Cement Division for the Rohrdorfer Group. “Everything had been planned down to the last detail by my team and by Siemens in advance. We are delighted to now have a state-of-the-art drive system at work in our mill. This project has meant a hugely reduced risk of failure for the mill, which is so vital to our whole production process, and vastly improved availability over the coming years.” Franz Stocker, Head of the Electrical Department at the Rohrdorfer works and in overall charge of the project right from the initial phase, confirmed: “It was the excellent standard of cooperation between our team and Siemens that was key to the success of the project. Right from the very first meeting when we were still seeking the best technical solution for our modernization project, Siemens demonstrated a very high flexibility, examining a range of alternative options and providing excellent support throughout. We had decided, for instance, to program and commission the new interface to the PLC ourselves. Or we transferred the system test of the new converter from the Siemens factory to our own plant, so speeding up the commissioning process and cutting out on unnecessary duplication of work processes. Completion and implementation of the entire conversion project went as smoothly as clockwork, on schedule, precisely according to plan. Special thanks are due to the two teams, who quickly developed a good working relationship based on trust.”

Alongside the drive components, ­Siemens also installed a cRSP remote link (common Remote Service Platform), which enables rapid remote diagnosis and control of the drive by the experts at Siemens.


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