A Faraday effect based clamp-on magneto-optical current transducer for power systems

A new type of Faraday effect based magneto-optical current transducer (MOCT) has been developed. This paper presents the theoretical background, engineering design, and test results of this clamp-on MOCT. The sensor consists of two separate clamp-on parts. This design avoids the need to break the current carrying circuit in order to have the conductor enclosed by the optical path while keeping the same measurement accuracy. A feedback scheme has been designed to stabilize the light source. The MOCT has two output stages, 1 kA, and 20 kA, so that it can provide current signals for both power system metering and relaying devices.