Method for Operating a Magnetic-Inductive Flowmeter and a Corresponding Magnetic-Inductive Flowmeter

A magnetic-inductive flowmeter, comprising:

• a measuring tube for guiding a medium;
• a magnetic field generator for generating a magnetic field passing through the measuring tube perpendicular to the direction of flow of the medium;
• a pair of electrodes for tapping an electrical voltage induced in the medium in the measuring tube as a measuring signal;
• and
• a control and evaluation unit for determining a flow measurement value from the measuring signal;
• wherein the measuring signal is sampled several times in a measuring window periodically repeating at a measuring window frequency and at least one averaged flow measurement value is determined from the multiple sampled measuring signals from at least one measuring window;
• wherein the control and evaluation unit determines an amplitude spectrum of the sampled measuring signals of at least one measuring window in the operating state by means of a frequency analysis of the multiple, sampled measuring signals;
• wherein the control and evaluation unit determines at least one interference peak in the amplitude spectrum and the associated interference peak frequency by a peak detection, wherein the at least one interference peak has a peak frequency that is not a multiple of the measuring window frequency;
• wherein the control and evaluation unit identifies a critical measuring situation by the control and evaluation unit checking whether the determined interference peak frequency falls below a predetermined critical frequency distance to a multiple of the measuring window frequency;
• and
• wherein the control and evaluation unit determines a new measuring window frequency in the presence of a critical measuring situation and sets it as measuring window frequency so that there is no longer a critical measuring situation.

A method for operating a magnetic-inductive flowmeter, comprising:

• passing a magnetic field through a measuring tube having a medium flowing therethrough;
• tapping a voltage induced in the medium as a measuring signal;
• determining a flow measurement value from the measuring signal;
• generating measuring signal samples in respective measuring windows that periodically repeat at a measuring window frequency;
• determining an averaged flow measurement value from the measuring signal samples;
• obtaining an amplitude spectrum of the measuring signal samples by a frequency analysis thereof;
• determining an interference peak in the amplitude spectrum and an associated interference peak frequency that is not a multiple of the measuring window frequency;
• identifying a critical measurement situation by checking whether the interference peak frequency falls below a critical frequency distance to a multiple of the measuring window frequency;
• and
• in the presence of a critical measurement situation, determining and setting a new measuring window frequency.