Upgrade Fe-50%Ni alloys for open-loop DC current sensor: Design and alloy-potential characteristics

This paper deals with the DC current sensor with open loop and high accuracy, and describes the relationship between the latter and the core-material magnetic properties in the case of Fe-50%Ni alloys. It is pointed out that air-gap precision, nonlinearity B – H and hysteresis are the main sources of accuracy; the influences of mechanical stress and temperature on coercive field are quantified and have to be taken into account in the design of the sensor. It is shown by dedicated choice of grades and annealing that Fe-50%Ni alloys may vary their coercive field from 4–6 A/m down to 1.5–4 A/m depending on the final annealing treatment used.