Patent ID: 7260486

Claim:
A method for operating a magneto-inductive flow meter adopted to measure a volume flow rate and/or a flow velocity of a flowing fluid, the meter comprising a measuring tube for conveying the fluid to be measured, a magnetic field system, which includes at least one field coil, through which an exciter current flows for producing a magnetic field passing through the fluid at least partially perpendicularly to a stream direction, and electrodes for producing at least one measurement signal corresponding to a voltage arising in the fluid flowing through the measuring tube, the method comprising the steps of: producing the magnetic fluid passing through the fluid; sensing electrical potentials induced in the flowing fluid; and producing said at least one measurement signal, and supplying the at least one measurement signal to an evaluating circuit, wherein the step of producing the magnetic fluid includes the following steps: changing a voltage driving the exciter current, at a first point in time, t 1 , from an instantaneous first voltage level, being different from zero, to a second voltage level, being constant or controlled to be constant, for increasing to a maximum current value, a current strength, of the exciter current driven by the voltage and flowing in the at least one field coil, said second voltage level, being selected to be greater than said first voltage level, and changing the voltage instantaneously driving the exciter current, at a second point in time, t 2 , from said second voltage level, to a third voltage level, being constant or controlled to be constant, for sinking the exciter current instantaneously flowing in the at least one field coil, from said maximum electrical current value, to a constant electrical current end value, predetermined for the exciter current said third voltage level, being selected to be smaller than the second voltage level.