Rogowski Coil With Ferromagnetic Powder Core

We have used nanocrystalline powder to build a core for Rogowski coils suitable for application in energy meters. The sensor linearity error is 0.32% of full scale (FS) of its 20 A range, which is acceptable for this application. The main advantages of the new core are 15-fold increase in sensitivity, which results in lower noise, and high rejection of direct current. It operates at up to 1000 A dc with 20% change in sensitivity. Resulting accuracy of power measurement using a single-chip digital power meter is 0.22% FS.