The company Varta Consumer Batteries GmbH & Co. KGaA is part of the Spectrum Brands Group, an American conglomerate including well-known names like Remington. Varta is a provider of innovative quality products in the areas battery, accumulators, charger and pocket lamps. Global locations guarantee an expansion of the market position especially in central Europe.

The situation and scope

Alkaline batteries are produced in Dischingen (Germany), the only manufacturing location in Europe. As a part of modernizations in the production area the plant for the production of cathode (granulate) which is necessary for the production of cathode rings of alkaline batteries has to be equipped with new control and operation components. The basic relevance was to leave the procedural installation and functionality unchanged. Due to that this installation has a key position in the whole assembly. A failure of this installation could not been compensated by other measures, so great accuracy during planning and realization of the project was necessary.

Before the modernisation of Siemens SIMATIC S5 as well as SIMATIC S7 control components were already applied in the installation. There were only five days of production for the complete remodelling of the assembly. The basis for the future approach was the circuit diagrams, the available S5 programming code of the existing controls as well as the operating instructions for single parts of the installation.

Realisation

The implementation of all measures was made by XAPI Software GmbH located in Speyer. XAPI develops software for weighing and dosage processes in the area of automation engineering and is one of the speciality suppliers on the market. Since 2006 XAPI has also had an official VIPA system partner; some projects were realised successfully together in the past.

For the realization of these project the VIPA system 300S with SPEED7 technology was applied. For this, six CPUs 315NET in total as well as a CPU 317NET were applied. With this constellation cycle times of less than 20ms, in normal cases even under 9ms were achieved.

Due to this fast cycle time is was only possible to use the available SIWAREX M modules as signal modules, as the SIWAREX M dosing function used so far were replace by dosing modules within the new S7 programs. This measure opens the possibility to freely choose the connection of the scales now and in the future. There is no need for the additional application of discrete Ethernet modules due to the integrated Ethernet interface of VIPA CPUs and their CP343 functionalities. Furthermore the Ethernet interface can be used for the connection to the applied webserver from XAPI via the TCP/IP protocol. Overall the CPU change leads to a considerable performance increase.

By the application of VIPA SPEED7 CPUs a cycle time of less than 20ms (9ms) was achieved as already described above. In comparison to the applied S5 CPU which achieved a cycle time of 800ms/1s, the VIPA CPU is faster by a factor of 40 to 100 times. The high performance was also necessary, as the program process of the newly applied Batch system depends on the cycle time of the PLC system. So it succeeded in removing the complete weighing engineering into the PLC and to realize the technical process faster.
The result is an additional positive effect that the reaction time of the whole application was able to be reduced. The various application possibilities of customary MMC cards in the CPUs like cyclic data storage or the storage of the latest release numbers were the reasons for the application of VIPA CPUs. XAPI has already had good experiences with this function in the past and so they expanded the software with CPUs from VIPA.

The large work memory of standard 1MB at the CPU 315SN/NET and 2MB at the CPU 317SN/NET offers enough memory reserves, as the storage efficiency of the CPUs in the VARTA control is around 50%. Subsequent project expansions are possible without CPU change. Especially with the VIPA specific MMC memory extension card a flexible storage adaptation with additional efforts is possible.
XAPI applied the VIPA CPU 315SN/NET or 317 SN/NET respectively in connection with their own software due to the high memory capacity and the fast cycle times of the VIPA SPEED7 CPUs. At least the Siemens CPU 317 had to be applied as a competitive product in order to achieve a comparable performance. Due to the perfect price-performance ratio the end customer VARTA also decided for the VIPA solution. For the new server system a new platform with several virtual engines were selected. The new batch system, the new visualisation, the engineering station as well as the teleservice of XAPI among others are installed in the individual engines (see fig 4).

The available batch administrative system (Delphi application of several modules) was replaced by the standard software X-Batch from XAPI. The software is Web-based; so all PCs within the work group can access on to the server.

The application of the software X-PLANT form XAPI enables a comfortable operating and parameterization of the modules used. So delay times, turn-on and –off delays or measured-value parameterizations for example are completely readable or changeable via the visualisation. X-PLANT offers detailed diagnosis possibilities: so the circuit diagram of each group of the plant is stored as a PDF file in the visualisation. The S7 program including chip description and online values are visible via the extend diagnosis for each part of the plant. There is a system overview within the visualisation available, which allows an extensive diagnosis of single VIPA PLCs, the internal bus system (Profibus) and the superior network (Ethernet) as well as the connected server and clients.

Installation

To avoid extensive wiring work during the project realisation/installation the existing S5 modules remain completely unchanged. For this the allocation modules (SIMATIC S5 IM308-C) were used as slaves in the Profibus configuration of the new VIPA PLCs. Already existing S7 modules (e. g. SIWAREX M, digital and analog in-/outputs) were also connected to the DP slave. The new VIPA PLCs only need a power supply and a Profibus connection, which is already integrated in the CPUs.
A risk free inspection of the plant functionality was possible by the complete simulation in the test installation. These guarantee a fast and smooth installation. The whole plant could be immediately passed to the warm start up after signal test or manual start up followed by the start of production.

Plant description
 
The whole plant exists from three mixer lines, the interconnection between the lines will usually only be activated in case of error of single parts of the plant. To the single lines 13 silos are upstreamed, in which the source material is stockpiled. Depending on the processed formula the source material are weighed, buffered in a temporary container and than forwarded to the mixer pre-container of the single mixer lines. When all source materials of a formula collected in a mixer pre-container, the content passes through a screening machine in order to eliminate foreign substances.

The screened material goes into the mixer. Each mixer line has three additional scales for small components (e. g. scale 8, 9, 10) and a scale for electrolyte (e. g. scale 4). When all fixed components of the formula are filled up into the mixer a dry blending is carried out. The procedure of the blending is contained in the formula. After dry mixing the electrolyte is added and the wet mixing starts. This procedure is also contained in the formula. After mixing the content is filled into the next mixing container, from which the material will be forwarded into the compactor. Here the fine-grained material will be mechanically compressed according to the procedure of pelletizing and the slugs gained are crushed in a coarse crusher and two fine crushers.

Control description

In the plant described the VIPA CPUs 315SN/NET and the 317SN/NET are part of the Ethernet network. Here the CPU 317SN/NET takes over the central control function at the dosage of the raw material (AG 1), the six CPUs 315SN/NET are each the central control unit for the filling of the raw material (AG 7) as well as for the mixer and compactors (AG 2 up to AG 6).
All CPUs are connected via Profibus with S5 or S7 expansion racks (fig 4). The produced granulate is forwarded through a screen plant, where it is separated into fine and coarse parts. The screened fine parts are supplied to the mixer container for further compaction. The coarse parts are filled into mobile supply bins and are stored for processing in the cellular production.
The procedural setup of the three lines is identical. But there are differences between spatial and mechanical setup, at which augers or bucket chain conveyors are applied for implementing the material flow between the facilities. The filling of 13 raw material silos for pyrolusite, graphite and for smaller components is also integrated into the plant. The raw materials are packed in cargos or in big bags.

Depending on the way of supply a further automatization of different processes including the return of packaging material is also achieved here. The entire operation including the complete visualisation of the plant takes place in the control room. An additional manual operation of individual facilities is possible. At an additional work station the simulation with original components can be executed by means of a test application (fig 3).

Conclusion: On basis of control demands there were several reasons for VARTA or XAPI to apply VIPA controls.
Above all the high performance as well as the generous and flexible memory concept of the SPEED7 CPUs argues for the solution with VIPA CPUs.
The additional feature of the integrated Ethernet interfaces in the VIPA CPUs applied can be used for the connection of the applied web server of XAPI. This saves the application of additional discrete CP modules. The possibility of using customary MMC cards for the external data saving and the balanced price performance ratio completes the entire VIPA package.
The above described control of the mixing facility demands a reliable partner or supplier due to the great importance within the entire production process. So the past positive experiences of XAPI and VARTA with the application of VIPA products tipped the balance for the product selection.

Author: Mark Kohl, VIPA Sales engineer - In cooperation with Fa. Varta and Fa. XAPI