An autotransformer is an electrical transformer with only one winding. The auto prefix refers to the single coil acting alone, not to any kind of automatic mechanism. In an autotransformer, portions of the same winding act as both the primary and secondary sides of the transformer.
An Autotransformer can be used for step up, step down and split phase output balancing purposes.
Autotransformers are frequently used in power applications to interconnect systems operating at different voltage classes. It takes care of the load balancing.
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