Electromagnetic flowmeter is designed for the measurement of conductive liquids and instrumentation, its high accuracy, wide range ratio, no internal moving parts, no flow blocking parts, no pressure loss, anti-corrosion, anti-high pressure ability is excellent, adaptability, has been widely used in various production areas.
Because some installation sites are more complicated, various interferences will inevitably occur. Qingtian Instrument staff will explain several common anti-interference methods for electromagnetic flowmeters: Sensor zeroing: To eliminate the orthogonal interference caused by electromagnetic interference, two wires are connected to the two ends of the potentiometer on the elevator. The lead wire on the other electrode and the middle end of the potentiometer are connected to the inlet end of the converter respectively. At this time, two closed loops are formed, generating their own induced electromotive force and current. The two currents are added to the input resistance of the converter through the middle end of the potentiometer. At this time, the directions of the two currents are opposite. Before use, adjust the position of the contact point at the middle end of the potentiometer so that the two currents are the same in magnitude and can cancel each other out.
However, due to the limitation of production process, this operation cannot completely eliminate the influence of electromagnetic interference. If necessary, other methods are needed to further eliminate the influence of interference. Synchronous sampling technology: When the signal is continuous, the synchronous sampling technology can be used to sample the signal. However, attention should be paid to the selection of sampling area, width and starting point of sampling area. The sampling period is selected as an integer multiple of the power frequency. In this way, even if there is an interference signal, its average value is zero because its sampling time is a complete power frequency period, which can effectively suppress the influence of interference.
Digital filtering technology: This technology is a common technology in intelligent instruments, which can effectively complete the functions that analog filters cannot complete. It is easy to solve pulse interference, digital circuit interference, S/D converter high-frequency interference, etc. Effective grounding of the instrument: The signal output by the sensor in the electromagnetic flowmeter is very small. In order to improve the anti-interference ability of the instrument, the zero point potential of the sensor input circuit must be grounded. At the same time, the grounding of the sensor measuring tube shell can play a shielding role and reduce the electromagnetic interference of the outside world and the excitation system itself. The flowmeter needs to be grounded separately to avoid sharing the same ground with other instruments. The instrument grounding point should be far away from large electromechanical equipment to prevent the leakage current in the ground wire from causing cross-mode interference to the measurement signal.
Supmea has been producing electromagnetic flowmeters for many years. If you encounter any problems in the selection, installation, use and maintenance of electromagnetic flowmeters, you can contact Supmea staff at any time and we will answer your questions.
Hangzhou Economic Development Area，Hangzhou 310018，China
