New evaluation of low frequency capture for a wide bandwidth clamping current probe for ±800 A using GMR sensors

Magnetic field sensitive semiconductors used for current measurement work well, but do have restrictions. Offset, sensitivity, linearity, temperature drift and measuring range are often critical properties of a current probe, especially if it is realised with magnetic field sensors like Hall effect and any kind of ferromagnetic flux concentrator. This paper is focused on the working principle of a new evaluation method for a DC to low frequency current measurement device, utilizing magnetic field sensitive semiconductors, which is designed to be part of a wide bandwidth clamping current probe. Distinctive to this new method is, that an external compensation coil surrounds the sensing semiconductor and no ferromagnetic core is needed. The presented measurement method is extendable to a very wide range of current amplitudes. A clamping sensor head for a current probe has been built, assembling an array of GMR (giant magneto resistance) sensors driven and evaluated with this method. The performance of this prototype for ±800 A is presented.