A 20-year Warranty: Putting Production to the Test

Solar photovoltaics is the method of converting radiant energy (solar radiation) into direct current electricity. Transformer manufacturer Schwa-Medico Transformatorenbau & Industrieprodukte manufactures a variety of electronic transformers specially designed for photovoltaic converters at its production plant in Hungary. To be able to provide a 20-year warranty, Schwa-Medico pots its coiled products in heat conducting polyurethane using a dispensing system from Scheugenpflug. The resin filling protects the transformers from any adverse environmental effects. The heat conducting filler dissipates any heat buildup in the transformer.

It was Wolfgang Schmidt, CEO of Schwa-Medico, who made the decision to have Scheugenpflug provide a dispensing system for its production plant in Hungary. He explains why: “We were looking for an ingenious and technically advanced system which met all of our needs, was easy to operate and was available at short notice.” The firm needed a single machine capable of potting four different components without creating any air bubbles, to optimally dissipate the heat generated by the transformer.

The four types of electronic transformers vary in the shape and amount of dispensing material needed. To meet this challenge, Scheugenpflug programmed the clearly structured and easy-to-use Windows-based interface according to the customers, exact production requirements. In the A300 material preparation and feeding system, the material is tempered, carefully homogenized and kept under vacuum.

Due to the polyurethane’s moisture sensitivity, the material is protected during the dispensing process by being held under a constant vacuum. The entire system including the metering unit is designed for abrasive materials, so that the hard, jagged fillers used for the heat conducting filling cannot damage the pumps. Still under vacuum, the components are precisely metered by an 8-nozzle metering head fitted with a static mixer for two-component materials. The hardening agent is mixed thoroughly with the resin in the mixing tube and poured directly into the components in the vacuum chamber. Potting is carried out in two phases, which is standard for coiled products. After the first potting cycle, at approx. 20 mbar, the vacuum chamber is ventilated so that the resulting pressure difference fully immerses the coil in the filling material. The finishing layer is performed under normal atmospheric pressure. The complete cycle (112 parts per tray) averages a cycle time of 9 seconds per part.

Machine operators who have already worked with the system are extremely satisfied with its ease of operation and simple programming options – not to mention the reliability of results and longterm stability. After the curing process, the electronic transformers are sent to Germany, installed in the inverters and then integrated into photovoltaic systems. Once on the roofs of buildings, these photovoltaic systems can immediately begin the main task at hand: generating clean, renewable energy.

< Prev		Next >