Converter Duty Transformer is principally different from other transformers. Here, higher secondary current has high harmonics due to the distorted waveform. The converter to the transformer causes distorted current waveforms. This has to be considered as a distorted current that leads to higher losses and temperature rise in the transformer.
Transformers
Converter Duty Transformer
The Transformer is designed to feed full load requirement despite harmonics in the circuit due to converter load. There are, however, additional load losses due to harmonic currents in windings, like high leakage flux. Stray flux causes additional stray and eddy losses not only in the winding conductors, but also in transformer tank and steel structure. These losses cause local hot spots. To overcome this, a proper selection of winding conductor is required. Provision of suitable magnetic shield and directed oil flow for effective cooling along with additional cooling equipment must be done. There may also be special requirements regarding tolerances on the transformer short circuit impedance since it influences efficiency of the electrolysis process.