Abstract: The invention relates to measurement of a fluid flow, wherein a flow rate component of the fluid is measured along a selected direction. A magnetic field whose polarity varies over time is applied to the fluid, which presumed to contain electrically charged elements. First and second sensor electrodes (120, 121) are arranged to be wetted by the flowing fluid. The electrodes (120, 121) are spaced apart from one another along a line being substantially perpendicular both to the selected flow direction and a magnetic axis of the magnetic field. A DC-level drift of the sensor electrodes (120, 121) is prevented by supplying a control current (Ictrl-0; Ictrl-1) to each of the sensor electrode (120, 121), which has such sign and magnitude that a direct-current voltage level at the sensor electrodes (120, 121) relative areference potential is controled towards a predetermined voltage (DCset).

Abstract: The invention relates to measurement of a fluid flow, wherein a flow rate component of the fluid is measured along a selected direction. A magnetic field whose polarity varies over time is applied to the fluid, which presumed to contain electrically charged elements. First and second sensor electrodes (120, 121) are arranged to be wetted by the flowing fluid. The electrodes (120, 121) are spaced apart from one another along a line being substantially perpendicular both to the selected flow direction and a magnetic axis of the magnetic field. A DC-level drift of the sensor electrodes (120, 121) is prevented by supplying a control current (Ictrl-0; Ictrl-1) each of the sensor electrode (120, 121), which has such sign and magnitude that a direct-current voltage level at the sensor electrodes (120, 121) relative a reference potential is controlled towards a predetermined voltage (DCset).