Method for operating a magnetic-inductive flowmeter and magnetic-inductive flowmeter

A method for operating a magnetic-inductive flowmeter that comprises at least one measuring tube with an inflow region, an outflow region, and a measuring region located between the inflow region and the outflow region for conducting a flowing medium through the flowmeter, the method comprising:

• generating, via at least one magnetic field generator, a magnetic field passing through the measuring tube in the measuring region substantially perpendicular to a direction of flow of the medium;
• providing at least one pair of measuring electrodes in the measuring region of the measuring tube to tap an electrical voltage induced in the medium in the measuring tube;
• determining in a flow measurement mode, via at least one control and evaluation unit, a flow measurement value from the measured induced electrical voltage;
• arranging a first current circuit electrode and a second current circuit electrode in a region of the measuring tube in contact with the medium, at least when the measuring tube is filled with medium to a predetermined fill level;
• connecting the current circuit electrodes to a current source outside the measuring tube;
• specifying, in a fill level measuring mode of the current source, a target measuring current, to which the current circuit electrodes are subjected, the current circuit electrodes being arranged such that a fill level current circuit closes via a medium flow path in the medium at least when the measuring tube is filled with the medium to the predetermined fill level, the medium current path passing through the flow cross-section of the measuring tube in which the measuring electrodes are located, so that an electrical voltage drop results between the circuit electrodes in the medium;
• detecting, via a dry circuit electrode and/or a dry measuring electrode in a fill level measuring mode, by measurement-based capture;
• and
• evaluating at least one of the following variables:
• at least one of the captured measuring electrode voltages, the measuring current emitted by the current source, a supply voltage caused by the current source at the first circuit electrode, and/or that a status “dry electrode” is at least indirectly signaled when a dry circuit electrode and/or a dry measuring electrode is detected.