A combined digital current and voltage transducer for power system has been developed. A Rogowski coil and a capacitive voltage divider are used respectively for the line current and voltage measurements. Active electronic components are used to modulate signal

and power supply for these components is drawn from line via an auxiliary current transformer. Measurement information is transmitted to the remote receivers by optical fibers. The whole system meets 0.5% accuracy for metering and provides large dynamic range coupled with good accuracy for protective relaying purpose. The system proposed is small in size

low in cost

disturbance proof

and easy to connect to upgrade computer. So it is an ideal detection unit for intelligent apparatus.