In order to be able to continue to produce top quality steel at a good price after the Y2K rollover, extensive modernization took place in the Salzgitter AG steelworks. The final stage of these measures was putting the VPL plant, a new secondary metallurgic center into operation. With this system (vacuum system, crucible furnace and alloy plant) it was possible to implement state-of-the-art steelworks technology, together with optimum logistics in flexible incorporation. 12 (!) Simatic S5 155U PLCs are responsible for their smooth operation.
Optical data light barriers allow signal traffic on the automated railroad cars
Jumpering level with spring cage terminal blocks and Varioface
ELIN-EBG system planners back the Varioface system cabling for the wiring of PLC-I/O cards. The Varioface front adapters are simply connected to the I/O cards and are led to the jumpering honeycomb elements via a preassembled system cable using the "Plug and Play" principle.
The system connection at the rear of the honeycomb elements in the PLC cabinet as well as the switch cabinet feed-through in the jumper cabinet bring about a reduction in costs due to space-saving, as well as an excellent switch cabinet appearance. The latter offers clarity in the event of malfunctions or if the system is expanded. In the jumper cabinet, the incoming master cables from the sensors and actuators of the field devices are first routed consecutively onto the spring cage terminal blocks of the ZFK range. The necessary connections are realized between the spring cage terminal blocks and the spring cage jumpering honeycomb elements in this jumpering level. In this way the technicians from ESA-Elektro-Schaltanlagen (ESA electronic switch gear), the Braunschweig company which has been appointed with building the system, has made sure that additional wiring during expansion or subsequent modifications of the system could be carried out simply and quickly.
12,000 tons of steel go through
the VPL plant every day
Data transmission via optical data light barriers
After appropriate pretreatment, the liquid steel, about 12,000 tons of it per day, is transported into 200-ton containers, the so-called ladles, by means of railroad cars, which are automated rail vehicles, to the crucible furnaces of the VPL plant. The control unit of the railroad cars communicates with the command level via PSM-ODL optical data light barriers, which have simply been linked into the serial transmission path.
Instead of a data line, an inexpensive alternative to trailing cables or collector wires requiring regular maintenance has thus been implemented. The PSM-ODL modules allow bi-directional data connections via infrared light up to 200 m.
The crucible furnaces, electric heating facilities with transformer capacities of 24 MVA, can increase the temperature of the smelts by up to 3° K/min in the range to 1,750° if necessary. Necessary metallurgic treatments such as setting lowest sulphur content for example, can thus be carried out. With the alloy plants and different alloys, analyses can be set to a thousandth.
These requirements are today an absolute must for top quality goods and are needed for pipework for oil field pipes in permafrost regions or for sheets for galvanizing in the car industry.
Startup during production
With the recently installed VPL system, the requirements can be set every 40 minutes for each 200-ton ladle, whereby the automation of processes is of considerable importance. This fast and easy, polarized connection technology of the Varioface system cabling guaranteed that the construction and system start-up of the plant could take place during the production flow.
Dipl.-Ing. Udo Haumersen