Sensor applications based on induced magnetic anisotropy in toroidal cores

The aim of the present work is to obtain anhysteretic hysteresis loops in amorphous ribbons by means of stress-induced anisotropies suitable for sensor applications. In order to reproduce the desired stress distribution, the amorphous ribbons were glued to plastic strips wound to form a toroidal core. Under this configuration, the dependence of the stress induced anisotropy on the toroidal radii, R, was analyzed in amorphous ribbons of composition Fe75Si15B10 and Co75Si15B10 with positive and negative magnetostriction respectively. The results show that a decrease of R gives rise to an increase in the corresponding stress induced anisotropy and the achievement of anhysteretic behaviour in the Co75Si15B10 ribbons. The magnetic properties of these toroidal cores enable the design of AC current sensors where the voltage induced through a pick up coil wound around the core is used to detect the current flowing through a conductor coaxial with the toroid sample axis. A technical description of this type of sensor is here reported. (C) 1997 Elsevier Science S.A.