How to identify electrode polarization issues in electromagnetic flowmeters

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The electromagnetic flowmeter does not display the flow rate, but the issue is resolved after power is restored. A significant polarization voltage exists between the two electrodes, and this can be attributed to electrode polarization; the so-called polarization is caused by an excess of positive or negative charges on the opposing electrodes, which creates a strong capacitive effect that prevents current from flowing properly. In other words, it is the phenomenon in which the electrode potential deviates from the equilibrium potential when an electric current flows through it. Electrode polarization in electromagnetic flowmeters is usually not caused by issues with the material used, but rather by the method of excitation. If a DC excitation method is used for the electromagnetic flowmeter, and the flow rate of the medium is low along with the medium having corrosive properties, the likelihood of polarization increases. The three-value low-frequency rectangular wave excitation method (with a period equal to 1/8 of 50Hz, and an excitation current that varies according to a sine law) can eliminate the polarization interference caused by the direct current magnetic field. It has very good zero-point stability and addresses the impact of perturbation potentials. For such a situation, it is necessary to select an appropriate brand and type of electromagnetic flowmeter, increase the flow rate appropriately, and of course, choosing the right electrode material is also important.