ABSTRACT
The autotransformer can provide a step-up voltage or a step-down voltage with respect to the input with good regulation. The biggest advantage of an autotransformer is the reduction in size, weight, and cost compared with an equivalent isolation transformer, as long as the designed secondary voltage is within limits of the primary voltage. The output power is of greatest interest to the user. To the transformer designer, the apparent power which is associated with the geometry of the transformer, is of greater importance. The core of an isolation transformer has only two windings in the window area, a primary and a secondary. The voltage, current and VA rating of a buck autotransformer is the same as an isolation transformer. The main difference is the apparent power, calculation and there is no electrical isolation between primary and secondary.
