Optical AC Voltage Sensor Based on Two $\hbox{Bi}_{4}\hbox{Ge}_{3} \hbox{O}_{12}$ Crystals

This paper introduces an optical ac voltage sensor utilizing two bulk Bi₄Ge₃O₁₂ crystals as the sensing element. One crystal is based on transverse Pockels effect and sensitive to the electric field strength. The other crystal is located inside the ground potential electrode. The measurement principle has been described, and a prototype of the sensor has been constructed and evaluated. AC voltage measurements on the sensor show good linearity and accuracy.

I. Introduction

Optical voltage sensors (OVSs) for ac voltage measurement have been investigated for many years. Applications in the electric power industry have also been addressed [1]–[4]. In contrast to the conventional voltage sensor technology (e.g., inductive voltage transformers or capacitive voltage transformers), the OVS has inherent and advantageous features, such as wider bandwidth, larger dynamic range, and lighter weight. Light transmission to and from the region of voltage measurement is done by optical fibers which bring inherent immunity to electromagnetic interference and compatibility with low-voltage analog and digital equipment used for metering and relaying applications.