Ferromagnetic materials excited by a distorted periodic field source

The aim of the authors is to discuss the magnetic behaviour of the ferromagnetic materials used in industrial applications, when the cited harmonic distortion of the excitation is working. To show the characterisation of the hysteresis loops performed by these materials, various experimental tests have been executed measuring the hysteresis loops presented by a toroidal nucleus made of mumetal (e.g. that used for differential relay sensor).