Influence of magnetic permeability in phase error of current transformers with nanocrystalline alloys cores

•We present a study about the influence of magnetic permeability in CT phase error.•The increase of magnetic permeability reduces the CT phase angle error.•Nanocrystalline alloys exhibit higher permeability than FeSi alloys.•CT with nanocrystalline alloy presents lower values of phase error than CT with FeSi. In this paper are presented an analytical and experimental study about the influence of magnetic permeability in phase error of current transformers (CT) with nanocrystalline alloy core. The interest in nanocrystalline alloys in CT cores is based on their magnetic characteristics, e.g., high relative magnetic permeability, low coercive force, and narrow hysteresis loop. To check the influence of the magnetic permeability in the phase error, some experiments were performed such that the only difference in the experimental setup was the ferromagnetic core of the current transformer. In these experiments were investigated four nanocrystalline alloys, with different composition, and a grain-oriented FeSi alloy. From the experimental results obtained, the magnetic characterization of the alloys under test confirmed the premise that the nanocrystalline alloys have superior values of magnetic permeability, lower coercive force and minor hysteresis loops. In tests with CT can be observed that those with nanocrystalline alloy toroidal core presents lower values of phase error in comparison with the CT with FeSi toroidal core, under the same rated conditions.