A MINIATURE DC CURRENT SENSOR-BASED ON MAGNETOIMPEDANCE

A dc electric current sensor, based on the magnetoimpedance phenomenon , is presented. The basic element of this sensor is a nonmagnetotstric tive, amorphous ferromagnetic wire of composition (CO0.94Fe0.06)(72,5) B15Si12.5, in the as-cast state. The de current to be monitored flows through a solenoid, and the magnetic field produced by this solenoid o n the wire leads to a controlled decrease of its impedance response. T his impedance dependence on the axial field is used to measure the de current. An important feature of this sensor is its reduced dimensions , since the whole device (sensing wire, solenoid, ac current generator ) fits into a 2X2X1 cm(3) volume. A discussion on its thermal stabilit y, reproducibility, and wire contact preparation is presented. (C) 199 7 American Institute of Physics.