It is often said that small is beautiful. But when it comes to technology, there are numerous other reasons that smaller is better. In many applications weight and space requirements directly influence productivity, and much research effort goes into footprint reduction. Some products, however, have largely resisted this tendency. The minimum size of a power transformer is essentially determined by the laws of physics, as the core must have certain dimensions to accommodate the magnetic field. One especially challenging application area for transformers is traction. The more space the trans- former occupies, the less is available for passengers on the train. Its weight is also a factor in terms of permissible train axle load and additional energy needed to accelerate it. In terms of making this component smaller and lighter, the laws of physics fortunately provide some scope for improvement in the form of frequency. The higher this is, the smaller the required core. This principle is also found in low-power devices such as laptop chargers. But applying it to such large and heavy-duty items as traction transformers is not just about scaling. ABB has taken on the challenge and developed a prototype power-electronic transformer that is currently being tested in a real locomotive.
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