Current Transformer with Toroidal Nanocrystalline Alloy Core

An error compensation technique for measuring current transformers is described. It uses only passive components. An example is shown for current transformers installed in I50 kV switching devices. Initial ratio errors in the order of 4% and phase shifts around 20 min were reduced to 0.1% and 6 min after the compensation. The transformer with the compensation fulfils class 0.2 according to IEC standards.