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The period from September to December is the main season for sugar factories. As soon as the campaign – the technical term for this time ofthe year – is kicked off, not only the sugar is separated from the beet, but also the wheat from the chaff as this is the time when it becomes clear which technology is capable of standing up to extreme constant loading. For the control and monitoring of process air, a new motormanagement system was employed for the first time in a sugar factory and excitedly put to the test by the company’s experts.
Every time fall is approaching, the workload of companies operating in specialsectors increases disproportionately. For sugar beet processing, forexample, this period means having to master 24-h shifts without failures for roughly three months. Günter Leinfelder, master electrician atthe Südzucker AG sugary factory located in the Swabian town of Rain amLech, confirms: “During the campaign, all systems must function flawlessly.” For this reason, the Rain-based factory decided in favour of acomponent modernisation for its production processes.
The beets are unloaded from the incoming trucks with the help of a high-pressure water jet, which also serves as a pre-cleaning measure. Even though thewater required for this process and for the beets’ cleaning flows ina circuit and is re-used, a surplus accrues, which is treated in the works-internal purification plant. In addition to an anaerobic and aerobic level, this plant also accommodates so-called oxidation ponds where the sewage water is treated adding atmospheric oxygen.
These ponds are evenly ventilated via 38 nozzles, each of which is supplied withoxygen by a separate fan. The fans are driven by conventional three-phase asynchronous motors with a capacity of 15 to 30 kW. The strikingfeature of this system is the employment of a state-of-the-art motor management system. The decisive factor in favour of this solution was that the motors’ functionality can be monitored at all times not only from the control center, but also directly on site.
The “Simocode pro” motor management system by Siemens perfectly meets this requirement. This low-voltage switching device is available in two variants, namely the Simocode pro C compact and the Simocode pro V variable versions. The sugar manufacturer immediately selected the variable and thus expandable version.
Device replacement without PLC, laptop or manual programming device
Once the advantages as well as potentials offered by these devices became clear, the decision process was accelerated. Particularly for the maintenance unit, which lies in the area ofresponsibility of the electrical department, fast response times playa decisive role. As a further prerequisite, the decision takers requested the support of a local device replacement without the help of a control or other electronic device.
With Simocode pro, this requestis fulfilled ever so smoothly. The trick is a memory module, which canbe plugged onto the basic unit and reads out and stores all parametersettings. If the parameters change, they are consistently stored on the memory module. If a motor management system is replaced, this memory module is withdrawn and plugged onto the new device. After connection of the supply voltage, the parameterisation is automatically writteninto the device by the memory module. The new device operates with the same setting values as the previous device. The entire process takesless than 30 seconds. “This accurately meets our requirements and hasso far not been available”, underlines Günter Leinfelder.
The overall investment in this state-of-the-art control as well as monitoringtechnology follows the approach of increasing the systems’ availability to hundred-percent. Thanks to the multitude of options offered by Simocode pro, the sugar company has moved a fair step closer to this target. In addition to current metering, which is already offered by thestandard version of these low-voltage switching devices, also so-called current/voltage measuring modules can now be applied. These modulesmeasure the current via transformers and can even detect voltages of up to 690 V in the main circuit. This facilitates the additional processing and monitoring of even performance-related measurands in the device.
Monitoring of the drives’ ageing behavior
Thanks to thedetection of cos-phi, the active and reactive shares can be calculated, thus monitoring the actual effective power in Simocode pro. This way, the fan drives’ ageing behavior can be monitored and required measures can be taken before the beginning of the actual campaign. Since themid of 2005, it has even been possible to record measuring curves inthe devices.
The values stored in Simocode pro can be read out fromthe Simatic control via Profibus DP and transmitted to the process control system. This is carried out both cyclically as well as non-cyclically, assuring the immediate indication of any possible faults. Furthermore, the company’s experts plan the realization of a comprehensivepower management concept based on the options offered by the motor management system. After all, this enables them to shut down or start updrives in accordance with the individual requirements.
For the operation of the 38 fan drives, the intelligent Simocode pro devices werecombined with Siemens 3RT contactors and 3RV circuit-breakers. This way, complete load feeders with comprehensive protection, control and diagnostic options were assembled. By attaching a temperature module, even the drives’ temperatures could be monitored and displayed, therebyfacilitating the connection of up to three respective sensors. Furthermore, an expansion module for analog input and output signals between0/4 and 20 mA has been available since 2005, with the help of which filling levels, positions or, at the Südzucker factory, flow rates can be detected.
Despite the necessity of having to integrate the new control technology in the central control station, Günter Leinfelder attached great importance to the distributed operation. With Simocode proV, this balancing act was successful as not only device replacement with subsequent parameterization is possible on site, but also status and fault messages can be read out locally. For this purpose, a respective operating module is simply plugged onto the device. If an operatorconducts local tasks, he merely needs to carry the module with him tobe able to conduct on-site operations. On a surface of 36 mm x 96 mm,the new operating module can replace five conventional pushbuttons and ten indicator lights. With four freely assignable pushbuttons and seven individually usable LEDs, it assures maximum functionality and flexibility.
Motor management with ample extras facilitates headstarts
For Günter Leinfelder, the waiting period was worth it as themotor management system was not previously available with today’s functional scope. Needless to say that he settles for nothing but the bestas the production of sugar requires smooth but effective processes. Or, as Günter Leinfelder puts it: “Like athletes, we must consistentlyemploy the optimum equipment to assure maximum fitness for the ‘competition phase’.”
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