A Current Transformer (CT) is a device designed to reduce an alternating current (AC) to a much lower, safer level. It is usually found in electric power systems for metering and/or protective relaying purposes. They are used to measure the level of current flowing through circuits and in most cases are connected to a meter or other monitoring device. The current transformer uses the concepts of electrical transformer to transform current levels between the primary (higher current) and secondary (lower current) windings. A typical current transformer is a wire wound toroidal core transformer, with a single primary winding, connected in series with the load, and a multiple secondary windings designed to provide an output current proportional to the current flowing through the primary.