Magnetic Potentiometer of High Precision

A magnetic potentiometer is described, the measuring error of which is in the order of 0.1 percent. The measuring winding is on polished straight ceramic rods, the joints of which are kept free from magnetic field by magnetic screening. Thus a measuring frame for heavy currents arises, the mutual inductance of which is independent of the primary circuit situation and of neighboring busbars. The exact measurement of the ac voltages induced can be made with the aid of measuring contacts or also with integrating electronic amplifiers, so that the rms value, fundamental oscillation, and harmonics and phase angle of heavy currents can be measured reliably. The practical error effects in these devices have been examined by the Physikalisch-Technische Bundesanstalt, Berlin.