Development of a Wide-range Current Sensor with Regularly Arrayed Magnetic Pieces

Current transformers and Rogowski coils are used to measure electric current in power distribution equipments. In recent years, wide-range current sensors have had strong demands to standardize current sensors in those various equipments. However, it has been difficult to make a trade-off between the sensitivity and the size of a conventional current sensors. To overcome the difficulty, we developed a new current sensor where magnetic pieces are regularly arrayed inside the Rogowski coil. We made a comparative evaluation of the performances of the conventional and developed sensors with magnetic field analysis, and we achieved that the S/N ratio of the developed sensor was approximately 4.5 times higher than that of a Rogowski coil, and that the developed sensor had the measurement range of the current approximately 8 times wider than common current transformers. We also built a prototype which has the precision of the current sensing comparable to conventional current transformers.