What is characteristic of an autotransformer?

An autotransformer is characterized by having its windings electrically connected, which differentiates it from traditional transformers that have isolated or separate windings for the primary and secondary circuits. In an autotransformer, a single winding serves as both the primary and secondary winding; part of the winding is common to both circuits. This design allows for variable transformation ratios and a more compact and efficient structure compared to conventional transformers.

The electrical connection between the windings means that the voltage applied across the primary is the same voltage that is also present in the secondary, just adjusted based on the turns ratio. This property allows autotransformers to be more efficient in applications such as voltage regulation and power supply adaptation.

While autotransformers can operate at various frequencies, their defining characteristic is the way their windings are connected. They typically do not have multiple secondary outputs like traditional transformers, and although they might be used in high-frequency applications, this is not a defining feature of their construction.