Transformers that share a winding or part of a winding are called what?

Transformers that share a winding or part of a winding are classified as autotransformers. An autotransformer differs from traditional transformers in that it has a single winding that serves both the primary and secondary functions. In this design, a portion of the winding is tapped, allowing for the transformation of voltage levels while sharing the same physical winding. This can be more efficient and compact compared to using two separate windings, reducing material costs and physical size.

In the context of electrical systems, it is important to understand that autotransformers can step up or step down voltages effectively, making them suitable for applications where voltage regulation is required. Their ability to share a winding is the key characteristic that differentiates them from separate or conventional transformers, which feature distinct primary and secondary windings that do not share any parts.