The optical voltage transducer (OVT) is mainly based on the Pockels effect of an electro-optic crystal. According to the Pockels effect

the refractive index of crystal will change under the action of an applied electric field. This change will then make the linearly polarized light injected into the crystal along a certain direction generate an electro-optic phase delay that is proportional to the applied electric field. Since the electro-optic phase delay can not be directly acquired

the polarization interference measuring model is always employed. It converts an electro-optic phase delay into the voltage to be measured with light intensity modulation. Such a measuring mode

being dependent on light power detection

can only realize approximate linear measurement of limited phase delay. And

restricted by the temperature drift

the additional phase delay and half-wave voltage

the stability and reliability of OVT cannot meet the service requirements of the power system. This paper analyzes the limitations of polarization interference measuring mode and discusses the double optic route method.