New optical voltage instrument transformer

A new optical voltage transformer is designed based on the Pockels electro-optic effect of the crystal Bi₄Ge₃O₁₂ (BGO). Here, the reflection-type longitudinal modulation Pockels cell is described in detail. The longitudinal Pockels effect is called the quadrate electro- optic effect. The electric field could modulate the Polarization State of light as it passes through the transparent material. The optical output of the sensor is a closed quadrate to the electric field, which is performed by means of a digital signal processors. The processing algorithm accounts the optical fringes of the quadrate signals and produces a smooth and continuos reconstruction of applied voltage by using portions of the quadrate signals for interpolation. The technique works equally well regardless of whether the measured voltage is sinusoidal distorted.