Auto transformer

An auto transformer is a type of transformer that shares a common winding for both the primary and secondary circuits, as opposed to having separate windings like conventional transformers. This design allows for a more compact and efficient transformer, as it uses less material, especially for low-voltage applications. The primary and secondary windings are electrically connected, but the voltage is stepped up or stepped down based on the turns ratio between the two sections of the winding. Auto transformers are commonly used in applications where a slight voltage change is needed, such as motor starting, voltage regulation, and voltage reduction for certain industrial equipment. They are more efficient than conventional transformers for applications requiring only a small voltage change, but they are less isolated, making them unsuitable for applications where complete electrical isolation between input and output is required.