| 摘要 |
A method and device for obtaining an interference free measurement from a flowmeter. The flowmeter includes a measuring tube through which a flowable medium flows through a magnetic field generated by a magnetic arrangement and at least two measuring electrodes for detecting the measurement voltage induced by the flowable medium. The medium gives rise to interference voltages. The electrodes are connected to an interference-voltage eliminating unit by which common-mode interference is first eliminated by differentiation and unequal interference voltages are subsequently eliminated. In operation, the current voltage value U+(n) and U-(n) of each individual measuring electrode is compared with the associated preceding voltage value U+(n-1) and U-(n-1), and the interference-voltage eliminating unit outputs a measurement for further signal processing only when an equal, essentially proportional change in the voltage values U+(n) to U+(n-1) and U-(n) to U-(n-1) is found at each measuring electrode, which is evaluated as interference-free measurement.
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