Method and apparatus for electrode impedance measurement
Abstract:
A method measures electrical impedance of electromagnetic flowmeter sensing electrodes includes intermittently injecting an impedance measurement signal to at least one sensing electrode while a coil excitation drive signal is applied to flowmeter field generating coils. During a first interval, when the coil excitation drive signal is applied to the coils and the impedance measurement signal is injected to a sensing electrode, a first measurement signal is obtained. The first measurement signal includes an electromagnetically induced flow measurement signal and an electrode impedance measurement signal. During a second interval, when the coil excitation drive signal is applied to the coils but the impedance measurement signal is not injected to the sensing electrodes, a second measurement signal is obtained that includes an electromagnetically induced flow measurement signal. The first and second measurement signals combine into an output signal including the electrode impedance measurement signal without the electromagnetically induced flow measurement signal.
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