All-fiber module

3M Specialty Optical Fibers, West Haven, CT, is manufacturing an all-fiber, magneto-optic field sensor transducer module to measure electrical current flow through high-voltage conductors (138 kilovolts) in power transmission and distribution systems. The module features an annealed Faraday fiber-sensing coil and temperature compensation to maintain the sensor`s high accuracy, while minimizing effects on linearity and dynamic range. Passive thermal compensation meets American National Standards Institute class .3 accuracy. The sensor is a joint development between the National Institute of Standards & Technology and 3M through a Cooperative Research and Development Agreement with the U.S. Department of Commerce.