COMPENSATION FOR SENSITIVITY DRIFT IN MAGNETOELASTIC FORCE-MEASURING DEVICES

摘要

A magnetoelastic force transducer which is compensated for sensitivity drift is provided with a measuring transducer and a reference transducer (1) of the same material. In its simplest form the reference transducer may consist of a toroid. The two transducers are arranged in good thermal contact with one another. The reference transducer is arranged with a winding (2) for excitation with a current which at each moment is proportional to the supply current of the measuring transducer, and with a winding (3) for delivering a reference signal (Ur) proportional to its magnetic flux. The output signal of the reference transducer is rectified in a phase-sensitive rectifier, the output signal of which is compared with a constant reference voltage. The deviation controls the phase position of the control voltage of the rectifier in such a way that the output signal of the rectifier is caused to correspond to the reference voltage. The output signal of the measuring transducer is rectrified in a phase-sensitive rectifier, which is controlled by said control voltage and the output signal of which constitutes the temperature-compensated measured signal.