what is 3 phase auto transformer?

A three-phase autotransformer is a type of electrical transformer that uses a single winding for multiple phases, allowing for voltage transformation in three-phase systems. It consists of a common winding that serves as both the primary and secondary, enabling efficient voltage adjustment with reduced material usage. This design minimizes losses and is often used in applications like voltage regulation and power distribution, providing a compact and cost-effective solution for three-phase power systems.