Importance

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Abstract

A method of operating an induction distance sensor employs a sensor having a vane or tongue of magnetic material disposed movably between two inductive coils for changing their inductances in the opposite sense upon movement of the tongue. With respect to sensor signals U.sub.s and U.sub.e, the method employs the portion U.sub.sL of U.sub.s which is in phase with the imaginary part U.sub.eL of U.sub.e. Furthermore, the value U.sub.sL measured in this way is to be further increased by U.sub.e /U.sub.eL in order to compensate for the temperature influences on the ohmic resistances. Furthermore, the errors which can be caused by erroneous controls U.sub.e1 and U.sub.e2 are also corrected. For this purpose, the total voltage is applied at intervals to a reference sensor which consists of a precision resistance divider. In this way, the exact middle point M of the total voltage U.sub.e =U.sub.e1 and U.sub.e2 can be determined by measurement, and the middle-point voltage U.sub.m with respect to zero potential determined, which is divided into the real part U.sub. MR which is in phase with U.sub.e and the imaginary part U.sub.ML which lags behind it by 90.degree.. With the phase angle .alpha. between U.sub.eR and U.sub.eL, the correction value is .DELTA.U.sub.sL =U.sub.MR .times.sin .alpha.+U.sub.ML .times.cos .alpha..

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