CORELESS CURRENT PROBE AND A METHOD OF MEASURING DIRECT CURRENT

A coreless current probe has a U-shaped body with arms, an open end and a cross piece forming a closed end. The opening formed in the U-shaped body has a length not less than the width between the arms. The U-shaped body can engage around a conductor carrying a current to be measured. The U-shaped body has a number of coreless single point magnetic field sensors, usually Hall devices, distributed around the opening. An arrangement with six sensors has two sensors at the ends of the arms of the U-shaped body, two sensors at the closed end, and two sensors mid-way along the arms. Sensing circuitry applies factors to the outputs of the sensors and sums the results to produce a measured current value. The factors are selected so that the summed result is zero in any externally generated homogeneous magnetic field.