Patent ID: 7164263

Claim:
A device for measuring electric current comprised of a plurality of magnetic field sensors positioned around a current carrying conductor, where each sensor is sensitive to one vector component of the magnetic field generated by the electric current, where the sensors are positioned along one or more continuous closed paths encircling the conductor, where the sensors have substantially identical sensitivity along each closed path, where the sensors are equally spaced along the length of each closed path, where the vector direction of sensitivity for each sensor is oriented to be tangential with the closed path at each sensor location, where each sensor generates an output signal consisting of a steady offset voltage not dependent on the magnetic field present at the sensor added to a voltage that is linearly dependent on the magnetic field present at the sensor, where one half of the sensors are arranged to provide one polarity of output signal in response to the magnetic field generated by the current carrying conductor, where the other half of the sensors are arranged to provide the opposite polarity of output signal in response to the magnetic field generated by the current carrying conductor, where the outputs of the sensors having the same output polarity are averaged together to create two averaged signals, and where the two averaged signals are differenced to create an output signal that is proportional to the current flowing in the current carrying conductor and is substantially free of the offset voltages originating in the outputs of the magnetic field sensors.