The effect of temperature characteristic of Faraday rotator to passively demodulated all optical fiber current transformers

In order to move signal detecting point to the most sensitive position and improve the immunity of the system at the same time, the scheme named passively demodulated all optical fiber current transformer (AOFCT) inserts a Faraday rotator of 22.5 rotation angle between fiber (lambda/4) retarder and leading fiber. To improve the performance of this type of all fiber current transformer, after considering the temperature features of a large proportion of Faraday crystals, the effect of the Faraday rotator's temperature properties on temperature stability of the passively demodulated AOFCTs are theoretically analyzed and numerically calculated. The results show that the errors induced by the Faraday rotators are beyond the requested values in the International Standard IEC 60044-8:2002 of International Electrotechnical Commission (IEC) and the State Standard of P. R. China GB/T 20840.8-2007. Finally, to solve this problem, some possible solutions are suggested.