Application of fibre optical current transducer to protection

This paper describes the design of a fibre optical current transducer based on a mirror Faraday rotator. Computer simulation techniques are used to model the transducer, and to assess its operating performance. The transducer is used to measure the fault current waveforms encountered on a 33 kV distribution feeder. The measured waveforms are processed by a current differential scheme applied to the protection of this feeder. The operating performance of the protection is analysed and compared with the performance obtained when using conventional current transformers. Conclusions are drawn regarding the advantages and disadvantages of using fibre optical current transducers in protection relaying