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Large aquaria are to grant us deep insights into such eco systems and give us a close understanding of nature. A full-service manufacturer of such aquaria employs devices for the drive and control technology as are used in industrial applications. | ||||||||||
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To create this impression and assure that the aquarium visitors will recall this event for a long time, the technology behind the large glass panes must function impeccably. Franz-Josef Vennewald, owner and executive manager of VewaTech, a company specializing in aquarium building, also confirms this: "The requirements placed upon technology have been continously increasing with the dimensions of such modern saltwater aquaria." For this reason, low-voltage switching devices and controls used for these applications are subjected to the same requirements as prevail in the industry. With his professional experience of 26 years, the "marine" expert develops the perfect solution for every requirement. Amongst others, this is proven to the shark aquarium in the Vienna "Haus der Meere", which was put into operation at the end of 2006. According to his words, "this was a great challenge", as the aquarium with a capacity of over 270,000 litres had to be "fitted" into the existing building structure of an old flak tower and the complete technology embedded in a room as small as 2.2m x 6m. In addition, the customer requested the following: "An operating power of maximally 18 kW must not be exceeded."
The motor feeders consisting of 3RT coupling relays and 3RV motor starter protectors are normally mounted and wired individually by the company. With largescale projects, it is, however, reasonable to use the prewired combination of both components offered by Siemens. "This saves a considerable amount of time", confirms Vennewald. In addition, the complete 3RV19 infeed system offers further advantages such as the comfortable power infeed and distribution for a group of several circuit breakers or complete load feeders. The 3RV19 system is based on base plates, which can be modularly mounted side-by-side and are equipped with up to three slots for the contactor/motor starter protector combinations. The power supply from the infeed down to each individual motor starter protector or contactor is realized by means of plug connectors. Thanks to the covered contacts, the system offers protection against contact. For connection of consumers up to 5.5 kW, springloaded clamping technology can be used and for consumers up to 11 kW, screw technology is employed. Vennewald adds: "In aquarium technology, it is sufficient to screw-fasten the contacts. However, in applications which are subjected to frequent vibrations, spring-loaded clamping technology is more advantageous." VewaTech operates as a general contractor in the market and thus enjoys a certain exceptional position. Whoever wants an aquarium and opts for the Hamm-based expert can be sure to receive a "turn-key" solution - i.e. including planning, design, technology, equipment, fish stocking and service: "This is why we favour serious, reliable and future-proof suppliers." For example, also the Axel Springer publishing house utilized the described portfolio of products and services for its Berlin building, in which two viewing aquaria containing 4,000 litres were installed, which now "float" above the visitors’ heads in the foyer.
For example, large salt-water aquaria must be cooled within a narrow tolerance range. Water circulation alone - comprising the complete contained water volumes and normally taking place once an hour - and the impressive illumination would lead to a high temperature rise. Additionally, the mostly used acrylic glass panes have a further insulating effect. Sea basins for large fish should be maintained at a temperature of approx. 18°C. Yet, also the water levels, the salinity (salt content), the redox potential (oxidation reduction potential = indicator for the determination of a water’s biological self-purification capacity) as well as the pH level of the water must be continuously monitored. In addition, zoological gardens increasingly integrate vast underwater worlds in their facilities. This way, zoos can offer attractions, which draw visitors even during the bad-weather months. Such project, for example, was realized in the Austrian town of Schmieding near Wels, where a seawater aquarium for large fish with a capacity of 300,000 litres and a coral reef aquarium with ornamental fish were built in 2006. The idea of this project is to highlight evolution from the big bang to today, of which the underwater world forms part. "With this attraction, the zoo will certainly continue to climb the visitors’ popularity scale", says Vennewald.
For this task, they rely on the very finely adjustable devices of the Micromaster range, which offer sophisticated vector control. In the future, these devices can be replaced by the new Sinamics G120 range, introduced on the Hanover Trade Fair 2006. They offer a series of new functions, including, amongst others, the safety functionalities, the communication capability via Profibus and Profinet, the increased ruggedness thanks to a new cooling concept as well as an innovative power module with a high regenerative feedback capability. A sensitive speed control is extremely important to effectively spare the pumps during start-up and rampdown and adjust the optimum operating point during operation. "Particularly in salt water, outgasing is very critical", emphasizes Vennewald. This is because the bubbles, which inevitably form during pump operation, can very easily collect in the gills of the fish, where they obstruct their breathing. The formation of gas bubbles and their implosion, which is known as cavitation in pumps, must therefore be prevented in aquaria not only because of technical aspects. For reasons of service friendliness, the entire open- and closedloop control technology must be bus-capable. All sensors and actuators are connected to the Simatic S7 via respective I/O modules and analog cards. The PLC with the CPU 315 DP is equipped with a Profibus master and can thus communicate with the superior control technology. "This forms a basic prerequisite for the operator’s immediate detection of any value’s excessive deviation", explains Vennewald. To provide the aquaria made by VewaTech with maximum servicing and thus safety, the company owner will opt for remote maintenance in the future. This concept is based on an alarm feedback system that outputs both optical as well as acoustic signals and on the data transmission to the building control technology and SMS messages. "This way, we are always up-to-date can offer our support to customers long before an actual failure occurs", highlights Vennewald.
Against this background, Vennewald applies great accurateness to the technology he employs or develops. Amongst others, he developed a cleaning robot that cleans the panes from the inside. "This cleaning method is considerably faster and safer than the hour-long procedure of employing divers, including the safety personnel", he confirms. In the end, only one thing matters to him: the reliability to assure that all marine creatures can elegantly float through the water in the sensitive eco systems, which seawater aquaria form part of, throughout their lives without being “served”warm or cold as the result of an incident. Vennewald also shares this opinion: “With the functional diversity and reliability offered by state-ofthe- art switching and control technology, we have been making optimum experiences with our sensitive applications.” | ||||||||||
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Modular contactor/motor starter protector combination
The control as wakeful eye
Pump control protects the fish
Reliable technology saves livesCopyright © 2007 Thomas Publishing Company