Patent ID: 7117750

Claim:
A method for operating a magnetoinductive flowmeter, said flowmeter incorporating a measuring tube through which flows an electrically conductive medium, at least two measuring electrodes which are in direct conductive contact with the medium, at least one additional electrode that serves as a reference electrode or as a fill-level monitoring electrode, and at least one magnetic field coil that serves to generate a magnetic field which permeates at least part of the medium, said method comprising the following steps: impressing a predefined current between one of the measuring electrodes and the additional electrode, measuring the voltage generated between the measuring electrodes, deriving from the ratio of the voltage measured between the measuring electrodes and the current impressed between one of the measuring electrodes and the additional electrode a first resistance value, impressing the predefmed current between the other of the measuring electrodes and the additional electrode, measuring again the voltage generated between the measuring electrodes, deriving from the ratio of the voltage measured between the measuring electrodes in the previous step and the current impressed between the other measuring electrode and the additional electrode a second resistance value, determining the ratio between the first resistance value and the second resistance value, and detecting a critical load on one of the two measuring electrodes in the event that the ratio is outside a predefined quantitative range.