Autotransformer

An autotransformer is a transformer where the input and output voltages are derived from a common winding, leading to smaller and more cost-effective sizes. In part, this results in significantly smaller and thus more cost-effective sizes.

ATTENTION: There is no galvanic isolation between input and output circuit!

Note:
It is the user’s responsibility to check whether a transformer without galvanic isolation may be used. Among other things, it must be considered whether the insulation level of a device connected to the output of the autotransformer is sufficient.
Example: Operation of a 115V unit on the European 230V mains: We would generally advise against using this unit with an autotransformer and recommend a transformer with separate windings.

An autotransformer, also known as a “Spartransformator” in German.