Theoretical analysis of the temperature characteristics of an optical current sensing element

The temperature characteristics of an optical current sensing element are theoretically analyzed. The investigation results show that all following factors such as the peak wavelength shift induced by the ambient temperature variation of the optical source used, the Verdet constant variation with the temperature of the sensing material and the linear birefringence change with the changes of the temperature and stress inside the sensing head can exert harmful effect upon the output scale factor of the system and let the sensing cell show some temperature characteristics. The results also show that the effects of the first factor are greater than the others, and their varying trends are opposite and offset each other a little. As temperature changes from 283 K to 303 K, the scale factor changes 1.379%, which is greater than the national standard of 0.2%. These results indicate that proper measures have to be taken to stabilize the temperatures of both the optical source and the sensing head in the design of optical current transformers.