Patent ID: 7545136

Claim:
A device for measuring current, comprising a magnetic field sensor for measuring a magnetic field produced by a current flowing through a current conductor, the magnetic field sensor encapsulated into a housing, and a yoke, wherein the yoke is formed of an oblong piece of sheet metal of a magnetic material with a relative permeability of at least 100 such that it has a bottom side, two sidewalls and a top side, the top side running parallel to the bottom side and having an air gap formed between two ends with front sides that face each other across the air gap, wherein the yoke completely circumscribes the current conductor with the exception of the air gap, wherein the housing with the magnetic field sensor is placed inside the yoke and outside the air gap of the yoke, wherein the magnetic field sensor is placed at a first distance from the air gap and at a second distance from the sidewalls of the yoke, wherein the first distance is less than the second distance so that the magnetic field sensor is essentially passed through by stray lines of the magnetic field that issue from the ends of the yoke, and wherein a length of the yoke measured at a right angle to the direction of the current flowing in the current conductor and parallel to the air gap of the yoke is at least the same size as a height of the yoke measured at a right angle to the direction of the current flowing in the current conductor and perpendicular to the air gap.