A current transformer produces a reduced current accurately proportional to the current in the circuit which is too high to apply directly to metering and protecting instruments. A current transformer isolates the measuring instruments from what may be very high voltage in the monitored circuit. Current transformers are commonly used in metering and protective relays in the electrical power industry. A current transformer can be equipped with one or more independent magnetic cores with equal or different characteristics for measuring, metering and/or protective purposes.