Case Study

PLM solution transforms transformer design

Smit Transformatoren

Engineering time for custom-made order drops 50 to 60 percent with NX and Teamcenter

Custom-made transformers

Smit Transformatoren develops and manufactures complex, custom-made power transformers. Founded in 1913, the company has become the world leader in transformers used for the distribution and generation of electrical power in the range of 50 MVA to 1000 MVA and 400 kV to 525 kV. Smit meets customers’ requirements through its unique design and in-depth knowledge of production processes. The company is also equipped with the testing facilities necessary for ensuring product compliance with national and international specifications and standards.

The development and production of a power transformer is a complex process. The design process involves electricity, electromagnetism, heat exchange and mechanics. In a good and well-balanced transformer design, many parameters must combine seamlessly to meet the specifications. In addition, specific customer wishes and transport requirements must be met. Smit has written an electrical calculation program to properly assess all of the different factors. This program delivers a practically unique combination of data for each transformer, the so-called transformer blue print. This is how Smit Transformatoren delivers custom-made transformers.

Improving on 2D

Smit’s internal organization follows the principles of continuous improvement in its efforts towards cost reduction and improving production processes. The new tools made available through software technology constitute one of the driving forces in this respect. Well into the 1990s, Smit was using 2D CAD software and design operations had been automated to a large extent. The threshold at which Smit would switch over to 3D CAD was therefore high.Whole sections of a transformer were established automatically in 2D CAD. The company questioned whether this efficiency could be achieved in 3D. However, 2D CAD was missing one crucial element: flexibility. Anytime something had to be done outside the standards, design time increased dramatically.

A comparative study of 3D software led to the selection of the NX™ digital product development system (called Unigraphics at the time) from Siemens PLM Software. “For Smit, the most important selection criteria were flexibility, reliability and the relationship between customer and supplier,” says Ferd Mul, project engineer at Smit Transformatoren. “In addition, this solution’s open architecture and the configurability were a major bonus for Smit.” Finally, Siemens software was already working very well in several other applications at Smit.

In addition to choosing 3D CAD, Smit simultaneously made the equally important decision to improve the company’s efficiency by introducing the Teamcenter® product data management system (then called Iman), also from Siemens. This was prompted by the need to store information in a central location, to promote data re-use, and to make product data available to other departments in the company.

Optimized design process

Transformers are capital goods designed for a service life of thirty to forty years. At the conceptual level, they are always built on the basis of a group of fixed main components.Operational safety, reliability and durability are determining factors. The NX-Teamcenter implementation is based on a modular architecture, a concept that has been the most effective so far. The main components set the boundaries between modules. The main architecture, the so-called “transformer tree structure,” is filled with symbolic dummy parts. While retaining the relations (matings) between them, these dummy parts are replaced with different versions of the main component structures. Variable links are then connected from the tree structure to the modules. Spreadsheets are associated with the top level of the tree structure and the modules. Order information is incorporated into the transformer assembly via these spreadsheets.

The CAD implementation has now reached the optimization stage. Improved understanding, which has been obtained through experience gained, is now integrated into the models. The flow of information from the top level of the transformer to lower levels was sufficient to distribute the input from the calculation software to the main transformer sections. However, this approach did not take into account the mutual interactions between modules. As the dimensions of the inner transformer structure change, so must the transformer housing become bigger accordingly. Bidirectional connections are therefore necessary between the modules.With bidirectional connections, the top level of the transformer is not the only one transmitting data and the modules are not the only recipients. In this structure, all sections are both senders and receivers.

Modules must vary within ranges without steps. The capacity required to develop, test and maintain the modules and standard models must be built in at a structural level.On the other hand, models have to meet the standards. At the beginning of an order, three possible scenarios are possible: 1) it’s a new order that has few or no aspects in common with past orders; 2) it’s a “similar, less-than-2-years-old” order (the whole order model of the existing order is cloned); and 3) it’s a 100-percent repeat order. In this unique situation, a “super transformer level” is created that will encompass the complete existing transformer model as a substructure. Where a master model of the customer drawing is associated to this super transformer level, this makes the order unique in relation to the source order. This completes the order.

In the more common scenarios (1 and 2 above), the modules are subsequently placed in the transformer tree structure and connected. Then the calculation data can be read in and it becomes possible to select the correct configurations in the spreadsheets of the transformer top structure and modules. The major characteristics of the transformer take shape when the modules have been adapted to the modified data. A number of additional iterations may be necessary to coordinate everything in a constructive way. Finally, routing (piping) is then added to the outside as well as cabling (associative curves) on the inner section of the transformer. Possible tailor-made adjustments are also made manually in this phase.

Dramatic drop in engineering hours

The NX-generated 3D design is translated into an engineering bill of materials (E-BOM) in Teamcenter. Based on this list, a separate list of materials (Material BOM or M-BOM) is compiled that includes the procurement parts for each main component. This M-BOM is presented to the corresponding building groups in SAP via Siemens PLM Software’s Teamcenter for SAP (T4S) interface. The T4S interface also synchronizes the management of items of transformer-specific parts between Teamcenter and SAP. As a result, more and more parts get an item number. Before, these parts had to be re-ordered every time in accordance with a specific order.

“The order engineering lead time with NX and Teamcenter has virtually remained the same with regard to 2D, because Smit uses concurrent engineering only partly,” explains Mul. “On the other hand, the number of hours spent on an order is dramatically reduced. Time savings in the order of 50 to 60 percent are achieved for a special order.” Each similar order derived from an existing order achieves the same 50 to 60 percent time saving.

Through the use of Teamcenter PDM software in conjunction with NX, geometry and composition structure are built in parallel.With 2D CAD these were still two separate activities. “Moreover, it is possible to make a clear distinction between manufacturing and procurement parts by linking PDM and ERP,” Mul says. “Furthermore, this interface will provide us with more insight as to how often parts are used. This in turn will help us determine which parts should get an item number.”

Often, excessive attention is paid to the time saved in the manufacturing process itself, while this activity represents proportionally only a small part of product costs. “Other impacts on efficiency stemming from the introduction of NX and Teamcenter are more difficult to measure, but just as important,” adds Mul. “Think here of the manageability and reproducibility that are achieved by reusing configurable standard solutions. It is easier to predict the production output and thanks to the standard geometry, changes are more readily fed back into the new orders to be built.” This manifests itself immediately in the improved quality of the production process.

Along with NX’s influence, the ever-growing impact of Teamcenter is also evident. Smit’s engineering department is in the process of having Teamcenter take over the function of the existing publishing system. And until now, Teamcenter was only used in the manufacturing department. It is currently being rolled out throughout the organization, with the number of workstations rising from approximately 25 to 75 and eventually to 100. As this happens, it will become possible to share access to product data and production status information among multiple departments.

“Streamlining the manufacturing process is determined by a good knowledge of the product range,” says Mul. He points out that such knowledge provides clarity in how a product range of complex transformers can be optimally manufactured. He notes, “If there is one software solution that can best help Smit develop and leverage manufacturing process understanding, it is the NX-Teamcenter combination.”

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