What is a single phase Autotransformer? All Questions › Category: Electrical Machines › What is a single phase Autotransformer? 0 Vote Up Vote Down Akash Tiwari asked 4 years ago 1 Answers 0 Vote Up Vote Down Akash Tiwari answered 4 years ago A Single-phase autotransformer is a single winding transformer in which a part of the winding is common to both high-voltage and low-voltage sides.