An encoding system analyzes a data file to determine if portions of the data file include significant disparities in symbol probability. This ensures that transition to magnetic saturation is essentially completely precluded even in the case of redundant power supplies to which respectively associated line paths can be routed to and from the load device and, in consequence, with the current being shared differently, since the sum of all the currents passing through the common-mode inductor is approximately zero. The light emitting unit and the light receiving unit are fixed on the base.