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A few days ago, many friends asked us at Jiangsu Evergrande Instruments what causes low signal levels when using electromagnetic flowmeters for measurement What should be done when a small signal appears? Everyone is also not very clear about this issue. So today, Jiangsu Evergrande Instruments will explain to you the reasons behind low signal levels in electromagnetic flowmeters and the ways to address them! An electromagnetic flowmeter is based on Faraday’s law of electromagnetic induction; it calculates the fluid flow rate by measuring the induced electromotive force in a conductive fluid within a magnetic field. An electromagnetic flowmeter typically consists of a transmitter and a converter. The flow rate of the medium being measured is converted into an induced electromotive force by the transmitter, and then this potential signal is transformed by the converter into a standard signal (4–20 mA output) so that it can be used for indication, recording, or in conjunction with electric unit combination instruments. Electromagnetic flowmeters suffer from errors and are prone to interference in actual measurement environments and within industrial processes, such as the phenomenon of \"low signals\". This is mainly due to the following issues during use: I. Reasons for low signals in electromagnetic flowmeters 1. Due to external vibrations or strong magnetic field interference, when there is no flow of fluid, these external signals affect the sensor, resulting in \"false flow\" signals; such signals are also accumulated when they exceed the meter’s minimum measurement threshold. 2. An insulating layer adheres to the electrode surface, external interference occurs, or the milliampere signal generated by the electrode experiences zero-point drift during amplification and conversion, causing the signal to deviate from its normal value and thus resulting in errors. 3. When the pump starts, the liquid passes through the flow meter, cutting the magnetic field lines and generating a flow signal. All of this liquid is ultimately utilized in subsequent processes, so the flow measurement values obtained are valid and should be accumulated. When the pump stops, a small amount of liquid still flows back in the pipeline, cutting the magnetic field lines in the opposite direction and generating a minor signal as well. However, this liquid is not used in actual production, yet the flow meter continues to send signals to the PLC for sampling and accumulation, which results in significant errors. 4. When the pump starts, the liquid passes through the flow meter, disrupting the magnetic field lines and generating a flow signal; all of this liquid is eventually utilized in subsequent stages, and the flow measurement values obtained are useful, so they should be accumulated ； When the pump stops, a small amount of liquid still flows back in the pipeline, disrupting the magnetic field lines and resulting in small signals. However, this liquid is not utilized in actual production, yet the flow meter continues to send signals to the PLC for sampling and accumulation, which leads to significant errors. 5. Due to external disturbances or strong magnetic field interference, in the absence of medium flow, such external disturbances act on the sensor, generating \"false flow\" signals; these signals are also accumulated when they exceed the preset measurement threshold. 6. An insulating layer adheres to the surface of the electrode; external interference may occur, or zero drift can arise during the amplification and conversion of the milliampere signals generated by the electrode, causing the signals to deviate from their normal values and thus leading to errors. II. Methods for dealing with low signals in electromagnetic flowmeters The issues caused by interference signals cannot be resolved through process design; solutions must be sought in terms of process control. It can be processed through both hardware and software methods. 1. The hardware approach can be implemented using comparison circuits and electronic switches; this method is primarily used to filter out interference signals, but it increases the production costs for enterprises. Since there are many flow meters in a single production unit, many of such devices need to be replaced accordingly. 2. The software approach can be implemented using PLC software, and small-signal issues can be handled through the following process logic diagram. For more information, please visit the company’s official website at http://www.yb1518.com/. Please retain this link when reproducing the content! http://www.yb1518.com/UploadFiles/2012717174126829.jpg