Wound Current Transformer – The transformers primary winding is physically connected in series with the conductor that carries the measured current flowing in the circuit. The magnitude of the secondary current is dependent on the turns ratio of the transformer.

Also known as CTs, current transformers are devices that measure alternating current. They are widely used to measure high magnitude currents. A current transformer essentially lowers (steps down) a high current to a lower, safer level that you can manage properly. It steps down the current to be measured so that you can measure it with an average range ammeter.