Importance

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Abstract

The invention relates to a magneto-inductive method for determining the flow rate of a medium flowing through a measuring tube in the direction of the measuring tube axis. In order to be able to detect a coating formation on a measuring electrode early and with a high degree of certainty, a test pulse (U.sub.p) of defined pulse length (t.sub.p) is issued to the measuring electrode; at least one signal in response to the test pulse (U.sub.p) is determined at at least two measuring points in time (t.sub.1, t.sub.2), wherein the measuring points in time (t.sub.1, t.sub.2) lie in a time window (t.sub.end-t.sub.begin), which is so selected that no predictable disturbance signals occur on the measuring electrode in this time window (t.sub.end-t.sub.begin). On the basis of the response signal determined in the measuring points in time (t.sub.1, t.sub.2), the relaxation time, or the length of time until the reaching of a predetermined state of discharge (U.sub.i), of the measuring electrode is determined; on the basis of the determined relaxation time, or on the basis of the length of time until the reaching of the defined state of discharge (U.sub.i), of the measuring electrode, a malfunctioning of the measuring electrode (3,4) is detected, or becomes detectable.

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First Claim