ABSTRACT
International Electrotechnical Commission standards refer to rectifier transformers as converter transformers, while IEEE standards refer to these transformers as rectifier transformers. Rectifier transformers can be liquid-immersed, dry-type, or cast-coil technology. Dry-type transformers were primarily used in distribution-voltage classes. The traditional IEEE method for rating a rectifier transformer has always been the root-mean-square kVA drawn from the primary line. The Transformers Committee of the IEEE Power Engineering Society has accepted the term harmonic loss factor as more mathematically and physically correct than the term K-factor. A reasonable cutoff point and accurate harmonic spectrum are necessary to properly design transformers for harmonic loads. Rectifier transformers generally are designed with lower core inductions than standard power transformers to help offset the added core induction due to voltage harmonics. For some high-current transformers, these windings may be reversed, with the low-voltage winding wound on the outside over the high-voltage coil.
