AC current sensors are key components in the monitoring systems of electric power systems and are generally based on detecting the magnetic field induced around electric wires to measure the current into it. The most used current sensors are those based on Current Transformer (CT) that, in general, uses a ferromagnetic core and a coil around it in order to measure the primary-coil current by the secondary-coil induced voltage. To the best of our knowledge, all current sensors based on CT work on the undersaturation region of the ferromagnetic core material to take advantage of its quasi-linear feature, but limits its maximum operational current. In this paper, it is described a novel CT-based current sensor scheme that works on saturation region of a nanocrystalline core.