Three Winding Transformer

Abstract

Three winding transformers afford many advantages on large power systems and their use has become widely extended in recent years. Originally designed to eliminate insulation strains when operating on the star-star connection the third winding is now frequently used to supply power in the interchange of energy between two transmission lines, and for power factor correction of long high voltage lines by means of synchronous condensers. A number of concrete examples are given.
A brief discussion follows of the inherent charact, rristics of three winding transformers with regard to short circuit stresses and voltage regulation; some of the limitations are indicated. In conclusion the superiority of the three winding shell type over the core type is pointed out.