What should be done if an intelligent electromagnetic flowmeter is disturbed?

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　　Based on the characteristics of general HD-LDE intelligent electromagnetic flowmeter systems, the sources of interference for these flowmeters are discussed mainly from the perspective of hardware optimization; factors such as electromagnetic coupling and electrostatic induction are significant sources of interference noise in intelligent electromagnetic flowmeters. In an electromagnetic flow rate transducer, since the leads of the two electrodes are in an alternating magnetic field, an induced electromotive force is generated within the closed circuit of the leads once the transducer is powered on. This interference signal is superimposed on the measurement signal, affecting the operation of the system. Different excitation methods give rise to various electromagnetic interference issues. The DC excitation method is prone to polarization interference, while the AC excitation method is prone to orthogonal interference (90-degree interference), in-phase interference (i.e., power-frequency interference), and others. 　　Orthogonal interference refers to interference that is 90 degrees out of phase with the flow signal. When the HD-LDE intelligent electromagnetic flow transmitter operates in AC excitation mode, an alternating magnetic field is generated. The closed circuit composed of the electrodes, lead wires, the medium being measured, and the input circuit of the converter finds itself within this interfering alternating magnetic field. It is impossible for this closed circuit to be completely parallel to the magnetic field lines generated by the transmitter’s alternating magnetic field; as a result, some of these magnetic field lines pass through the closed circuit, thereby generating an interference electromotive force within it. In electromagnetic flowmeters, measures are taken both at the transmitter and the converter levels to eliminate or suppress such 90° interference. 　　In HD-LDE intelligent electromagnetic flowmeters, in-phase interference, power-frequency interference, or common-mode interference refers to interference signals that appear at both electrodes of the transmitter at the same instant, with identical amplitude and phase. When the flow rate is zero, that is, when the liquid being measured is at rest, the in-phase signal measured is the in-phase interference signal. There are many methods available to suppress in-phase interference in electromagnetic flowmeters. Regarding the transmitter, the electrode and the excitation coil are designed to be geometrically symmetrical in shape, size, and performance parameters, and are separately and rigorously shielded to reduce the influence of the distributed capacitance between the electrode and the excitation coil.