Optical fibre current sensor for circuit protection

An optical fibre current sensor has been designed and tested. This device, which uses the Faraday effect in optical fibre to measure electrical current, is intended to be applied to protection systems; it is regarded as a potential replacement for the iron cored current transformer in certain applications. The authors describe the design of an optical fibre current sensor, and review the considerations which led to the adoption of this particular design. Some background optical information is provided in order to make the design process clear, including outlines of the Faraday effect itself and of the major difficulty to be overcome; an effect known as linear birefringence. The results of current measurement tests on the optical fibre current sensor are presented and analysed in comparison with a current transformer. The advantages of the optical fibre current sensor for protection applications are summarized