Sagnac interferometer current transformer based on pulse multiplexing network structure

Abstract

The monitoring of current plays an important role in accurately grasping the working status of the power system. In this paper, a Sagnac interferometer (SI) current transformer (CT) based on pulse multiplexing network structure is proposed. The network multiplexing structure can multiplex a pulsed light into multiple sensing signals, eliminating interference from light source power jitter and sudden changes in optical path loss. SI consists of a uniaxial working coupler, a 45° Faraday rotator, two quarter wave plates (QWPs), and spun fiber. The uniaxial working coupler used can achieve slow axis operation and fast axis cutoff, and convert light into linear polarization light. After passing QWPs, the forward and backward light changes from linear polarization to circular polarization, which can be used for current sensing. Experiments have shown that it has good linearity and repeatability. The proposed sensor has the advantages of low cost and simple structure, which has broad prospects in applications with not very high precision requirements.