Both 3-Phase 2-winding and 3-winding auotransformers can be modelled using ETAP.

Autotransformers are frequently used in power applications to interconnect systems operating at different voltage classes. They are a type of electrical transformer with a single winding that acts as both the primary and secondary windings. Unlike a conventional transformer with separate primary and secondary windings, an autotransformer has a common winding that is tapped at different points to provide different voltage levels. This design provides a compact and cost-effective solution, especially for applications requiring small voltage adjustments. Autotransformers are commonly used to step up or step down voltages efficiently, offering benefits such as improved efficiency and reduced losses. However, they provide less electrical isolation between circuits compared to traditional transformers. ETAP can model 3-phase autotransformers with different voltage levels and grounding connections for various studies.