Laboratory evaluation of the hybrid fiber-optic current sensor

This paper gives details of the design, construction and laboratory evaluation of the pre-prototype optical current sensor developed specifically to prove the concept of the possibility of monitoring remotely operated electrical plant. The proposed sensor is of a hybrid construction, and uses an optical voltage-to-strain transducer to monitor a specially designed current transformer. In this application, the voltage-to-strain transducer is realized using a novel approach: it employs a fiber Bragg grating (FBG) bonded to a stack of multiple piezoelectric elements, with their respective electrodes connected in parallel. This approach greatly increases the measurement sensitivity; thus, the FBG can be interrogated using a classic scanning filter configuration rather than the interferometric technique. Moreover, since the absolute wavelength information is preserved, this brings the advantage of the simultaneous temperature measurement capability and enables the straightforward multiplexing of several sensors on one optical fiber.