A Scott-T transformer (also called a Scott connection) is a type of circuit used to derive two phase (2-φ) current from a three phase (3-φ) source or vice-versa. The Scott connection evenly distributes a balanced load between the phases of the source.

Nikola Tesla's original polyphase power system was based on simple to build 2-phase components. However, as transmission distances increased, the more transmission line efficient 3-phase system became more prominent. Both 2-φ and 3-φ components coexisted for a number of years. The Scott-T transformer connection allowed 2-φ and 3-φ components like motors and alternators to be interconnected.