A three-input induction transformer in which the phase relationship of the power output relative to the power input is selectable/adjustable after the transformer is placed in operation in the field. The transformer includes a primary set of windings and a three-pole, selector mechanism attached to the windings and which configures the windings in one of multiple serial configurations based on the selected position of the selector mechanism. Each transformer is configured so that the output-to-input phase relationship rotates a pre-determined number of degrees when the connectivity of the three-pole selector mechanism is changed.