Optical fiber sensors for the electric power industry

Optical fiber sensors are of particular interest for applications in the high-voltage environments of the electric power industry due to their characteristic properties including a dielectric nature, immunity to electro-magnetic interference, and small size and weight. We review our fiber-optic sensors for current and voltage and describe their applications in high-voltage substations. The current sensor employs the Faraday effect in a thermally annealed coil of sensing fiber. The current-induced differential phase shift of two-circular light waves is recovered by means of a novel polarization rotated reflection interferometer. The voltage sensor is based on the converse piezoelectric effect in a cylinder-shaped quartz crystal. An elliptical-core dual-mode fiber senses the crystal's piezoelectric deformation and is interrogated using low-coherence interferometry.