Abstract Method and apparatus for inductive flow measurement using a periodically reversed magnetic field, in which the useful signal is obtained by sampling and storing the signal voltage at equal but opposite values of induction of magnetic field and forming the difference of the stored sample values. There is formed between each two successive magnetic field impulses of opposite polarity an interval where the magnetic field is zero, there being generated in a compensation time interval within each magnetic field interval at the same time-interval before the next subsequent sampling of the signal voltage, a compensation voltage which restores the signal voltage during the compensation time interval to zero value. The compensation voltage value developed during the compensation time interval is stored and is employed until the next compensation time interval.
A method for inductive flow measurement by generating a magnetic field in a direction perpendicular to the flow and measuring the signal voltage induced by the flow across a pair of electrodes, comprising the steps of generating a periodically reversed magnetic field comprising field impulses of opposite polarity separated by magnetic field intervals in which the magnetic field has zero value, generating during a compensation time interval within each of said magnetic field intervals a compensating voltage of a magnitude and polarity adapted to compensate the disturbance voltage existing across said electrodes during said compensation time interval to zero value, storing said compensating voltage until the next compensation time interval and employing said stored compensating voltage for compensating the disturbance voltage contained in said signal voltage, sampling said signal voltage at a sampling time interval within each of said magnetic field impulses, each of said sampling time intervals having the same time distance from the preceding compensation time interval, and forming the difference of the signal voltage values sampled at successive sampling time intervals.
Claim 2
Independent Claim
174 words
A method for inductive flow measurement by generating a magnetic field in a direction perpendicular to the flow and measuring the signal voltage induced by the flow across a pair of electrodes, comprising the steps of generating a periodically reversed magnetic field comprising field impulses of opposite polarity separated by magnetic field intervals in which the magnetic field has zero value, generating during a compensation time interval within each of said magnetic field intervals a compensating voltage of a magnitude and polarity adapted to compensate the disturbance voltage existing across said electrodes during said compensation time interval to zero value, storing said compensating voltage until the next compensation time interval and employing said stored compensating voltage for compensating the disturbance voltage contained in said signal voltage, sampling said signal voltage at a sampling time interval within each of said magnetic field impulses, each of said sampling time intervals having the same time distance from the preceding compensation time interval, and forming the difference of the signal voltage values sampled at successive sampling time intervals.