Germany – Transformers – Ertüchtigung (Retrofit) des Generatortransformators Uk3 im Unterwerk Köln

Deutsche Bahn operates frequency-controlled network coupling transformers, or traction power transformers, in several central converter stations, which connect the public three-phase 50Hz power grid of the general national supply with the single-phase 16.7Hz traction power grid. The frequency-controlled network coupling transformers mainly consist of two rigidly interconnected rotating electrical machines – a doubly-fed three-phase asynchronous motor (50Hz) with a GTO power control and a single-phase synchronous generator with direct current excitation. The power from the public 50Hz three-phase grid is reduced by a 50Hz three-phase transformer from 110kV to the operating voltage/machine voltage (here 10.5kV) of the asynchronous machine and stepped up to 110kV by a single-phase 16.7Hz single-phase transformer. As part of the planned substation renovation (16.7 Hz) in the converter station Cologne, the transformer Uk3 (16.7Hz, 33.3 MVA, ABB) is to be removed and sent for an external factory inspection.