Schlumberger Industries

Arnaud De Montgolfier

R Wendell Goodwin

A differential electrical current shunt which is particularly adapted for the measurement of large currents with high accuracy and substantially free of errors due to ageing, connection resistance and differentials therein and thermally induced resistance changes. The shunt, according to the invention divides the large current into two substantially equal portions by forming a preferably elongated aperture in a conductor carrying the large current; the two portions of the conductor formed by the aperture having substantially equal but slightly differing resistances. The two conductor portions are formed with respect to a core such that the conductor portions each form a single turn coil on the core with the induced flux from each conductor portion opposing that included in the coil by the other of the two conductor portions. Since the conductor portions are in close proximity and formed of a unitary conductor and good thermal and electrical conductivity is assured at both ends of the unitary conductor, proportionality of resistance of the conductor portions is accurately maintained throughout a wide range of currents, resistive heating and other environmental conditions.

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Neuilly-sur-Seine, France

Arnaud De Montgolfier