The transformers described here are in the multi-megawatt range. They are rapidly becoming more important and have characteristics and features that are different in many ways from those of normal power transformers. Information about them has been incomplete, scattered and hard to find in the literature. Harmonics are of prime importance in these transformers. Their appearance and suppression are explained with an emphasis on making it easy to understand. Different winding arrangements are presented and their characteristics explained. Cores with gaps to limit inrush currents are also discussed.
