Optical fiber current sensor with small size for the high voltage watt-hour meter

Abstract

Fiber optical current sensor(FOCS) has widely used in the field of electric power measurement by which the current measured generally is hundreds of amperes even thousands amperes. A smaller fiber sensing coil is required in order to that the FOCS meet the needs of the high voltage watt-hour meter for measuring smaller current with the better performance. In this paper a FOCS with small size sensing coils (<10 cm in diameter) is achieved by using the special spun highly birefringent fiber. It is explained that the optical fiber sensing coils has stronger ability with resisting bending to achieve good signal stability. Specially the ability of resisting bending are analyzed in comparison between the fiber sensing coils by using the special spun highly birefringent fiber and the fiber sensing coils by using the low birefringent fiber (SM fiber). Finally, the designed optical fiber current sensor was tested and assessed in precision, temperature characteristics and linearity. The measurement error of the FOCS is within ±0.2% from -40°C to 70°C under considering temperature compensation, and the FOCS shows excellent performance to temperature characteristics, linearity and accuracy in a current range from 1A to 120A. The FOCS with small size will be help to achieving the high voltage watt-hour meter.