Autotransformers are a particular category of transformers whose coil consists of a single winding with intermediate taps instead of two separate windings, one for the primary and one for the secondary.

K-Factor single-phase and three-phase autotransformers, designed and tested in compliance with specific standards (EN61558-2-13), are the result of continuous work to optimize designs and materials.

The use of autotransformers is particularly cost-effective when the differences between input and output are minimal, while the savings decrease as this difference increases. Three-phase models are often used in areas where the 220V three-phase grid is still present, to step up the voltage to 400V three-phase. A special version of autotransformers also allows generating a neutral that makes voltages stable even in the presence of unbalanced loads, while a specific range of autotransformers is designed to facilitate the starting of electric motors. Autotransformers are also characterized by very high efficiency, making them convenient whenever galvanic isolation between primary and secondary is not required.