Vibronic measuring system for measuring a mass flow rate of a fluid measurement medium

A vibronic measuring system for measuring a mass flow rate of a fluid measurement medium, the vibronic measuring system comprising:

• a measuring sensor, including:
• at least one vibration element;
• at least one oscillation exciter for exciting and maintaining mechanical oscillations of the at least one vibration element;
• and
• an electrodynamic first vibration sensor and a electrodynamic second vibration sensor, wherein the first vibration sensor and the second vibration sensor are for sensing mechanical oscillations of the at least one vibration element,
• wherein the measuring sensor is configured to guide the measurement medium and to at least intermittently be flowed through by the measurement medium;
• a sensor housing for the measuring sensor;
• at least one first magnetic-field detector for sensing a magnetic field that is established inside the measuring system;
• and
• a measuring-system electronics electrically coupled both to the measuring sensor, including its at least one oscillation exciter and its first and second vibration sensors, and to the first magnetic-field detector,
• wherein the measuring sensor is positioned inside the sensor housing and the first magnetic-field detector is positioned outside the sensor housing,
• wherein the at least one vibration element is configured to be contacted by the flowing substance to be measured and to be vibrated at the same time,
• wherein the at least one oscillation exciter is configured to convert electrical power fed to the oscillation exciter into mechanical power causing forced mechanical oscillations of the vibration element,
• wherein the measuring-system electronics is configured to generate an electrical driver signal and to feed electrical power into the at least one oscillation exciter by means of the driver signal such that the vibration element executes at least proportionally useful vibrations, namely forced mechanical oscillations at at least one useful frequency, namely an oscillation frequency specified by the electrical driver signal, wherein the useful vibrations are suitable for causing, in the flowing measurement medium, Coriolis forces dependent on the mass flow rate,
• wherein the first vibration sensor is configured to convert vibrational movements of the at least one vibration element at a first measurement point into an electrical first oscillation measurement signal of the measuring sensor such that the first oscillation measurement signal has a first useful component, namely an AC voltage component at a frequency corresponding to the useful frequency and at an amplitude dependent on the useful frequency and a first magnetic flux, namely a magnetic flux through the first vibration sensor,
• wherein the second vibration sensor is configured to convert vibrational movements of the at least one vibration element at a second measurement point remote from the first measurement point into an electrical second oscillation measurement signal of the measuring sensor in such a way that said second oscillation measurement signal has a second useful component, namely an AC voltage component at a frequency corresponding to the useful frequency and at an amplitude dependent on the useful frequency and a second magnetic flux, namely a magnetic flux through the second vibration sensor,
• wherein the first magnetic-field detector is configured to sense the magnetic field at a third measurement point located outside the sensor housing and to convert it into a first magnetic-field signal that shows an amplitude dependent on a third magnetic flux, namely a magnetic flux through the first magnetic-field detector and/or on an area density of said magnetic flux such that the first magnetic-field signal follows at least a change in the third magnetic flux and/or in its area density with a change in the amplitude, and
• wherein the measuring-system electronics is configured to receive and evaluate both the first and second oscillation measurement signals and at least the first magnetic-field signal, namely to determine, on the basis of the firsts and second oscillation measurement signals, the mass-flow-rate measurement values representing the mass flow rate and, on the basis of the first magnetic-field signal, to at least qualitatively determine whether and/or to what extent the magnetic field is established at the first and/or second measurement points, or contributes to the first and/or second magnetic fluxes, and/or to determine whether a disturbance of the measuring system by the magnetic field is present.