| CPC G01N 27/07 (2013.01) | 10 Claims |
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1. A method for measuring an electrical conductivity of a medium with a conductive conductivity sensor having four electrodes immersible in the medium, wherein the four electrodes include a first current electrode, a second current electrode, a first voltage electrode, and a second voltage electrode, the method comprising:
immersing the four electrodes in the medium;
measuring a first impedance dependent on an impedance of the first voltage electrode and a medium layer adjacent to the first voltage electrode by introducing an alternating signal into the medium via a first signal path running via the first voltage electrode, through the medium, and to the second current electrode, measuring a first electrical variable dependent on a path impedance of the first signal path, and determining the first impedance on the basis of the first electrical variable;
measuring a second impedance dependent on an impedance of the second voltage electrode and a medium layer adjacent to the second voltage electrode by introducing an alternating signal into the medium via a second signal path running via the second voltage electrode, through the medium, and to the second current electrode, measuring a second electrical variable dependent on a path impedance of the second signal path, and determining the second impedance on the basis of the second electrical variable;
introducing an electrical alternating signal into the medium via the first current electrode and measuring a potential difference between the first voltage electrode and the second voltage electrode;
determining a corrected potential difference on the basis of the measured potential difference, the first impedance, and the second impedance, wherein the corrected potential difference corrects a measurement error caused by voltages dropping over the impedance of the first voltage electrode and the medium layer adjacent to the first voltage electrode and the impedance of the second voltage electrode and the medium layer adjacent to the second voltage electrode during measurement of the potential difference; and
determining a measured conductivity on the basis of the corrected potential difference,
wherein the alternating signal introduced into the medium for measuring the first impedance and the alternating signal introduced into the medium for measuring the second impedance each have a frequency equal to a frequency of the alternating signal introduced into the medium during conductivity measurement.
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