An Optical Current Sensor Based on Radial Grating-Polarizer Detection

Abstract

A novel optical current sensor based on radial grating-polarizer (RGP) detection is proposed in this paper to realize a linear measurement of currents for power systems. The sensor mainly consists of a magnetic concentration ring, a newly designed RGP, an image converter, and an image acquisition and processing system. The grating-polarizer is employed to convert the polarization plane's rotation of a linearly polarized light into the rotation of a circular facula, which then be converted into the horizontal linear movement of a linear facula by an image converter. Thus, a Faraday rotation angle can be measured directly by positioning the dark stripe in the facula. A 110-kV prototype with the rated current 300 A is completed, and trail run on the line. The performance shown that it meets the national standard of 0.5% accuracy class, and can achieve the linear measurement of the Faraday rotation angle in the range of ± 45°.