LDBE electromagnetic flowmeter measuring electrode contact resistance problem

Do you know what the fault phenomena of LDBE electromagnetic flowmeter are? Do you know the troubleshooting methods? Do you know product selection? Do you understand the installation location and installation requirements? Do you know how to set parameters? LDBE electromagnetic flowmeter is a flow meter with high precision, high reliability and long service life. Therefore, we are very meticulous in every aspect of the design of product structure, material selection, process formulation, production assembly and factory testing. Determination of electromagnetic flowmeter signal cable interference The signal cable is interfered by external electrostatic induction and electromagnetic induction, which will cause the zero point of the electromagnetic flowmeter to change. In order to determine whether the zero point change is due to the interference potential of the signal cable, it is necessary to determine the general scope of the interference and the degree of impact on the electromagnetic flowmeter. Although the measurement range ratio of electromagnetic flowmeter is 30:1, which is higher than that of vortex flowmeter and differential pressure flowmeter, it is also limited. When ordering a meter, many customers often compare it with a water meter and think that It can measure very low flow rates. Generally, it can only measure 0.1m/s. It is difficult for the electromagnetic flowmeter to measure correctly below this flow rate. Therefore, it is necessary to clarify the flow range ratio at the initial stage of ordering. When ordering, you cannot order based on the original pipe caliber. You must determine the instrument caliber based on your actual flow rate. Through the above introduction, we found that this is a very good flow meter product. Most liquid medium measurements choose it. Therefore, it is necessary for us to understand the relevant performance and technical parameters of this product, which will definitely be of great help to the correct operation and application in the future.

LDBE electromagnetic flowmeter finds problems by measuring electrode contact resistance: the electrode is the core component of the flowmeter and is used to measure the signal generated by the liquid medium. The electrode contact resistance measurement measures the liquid contact resistance value of the electrode spoon. , you can indirectly estimate the general condition of the surface of the electrode and lining layer without removing the flow sensor from the pipeline, which is helpful to analyze the cause of the failure. Polarization voltage of the electrode Measuring the polarization voltage between the electrode and the liquid will help determine whether the zero point instability or output shaking failure is caused by the electrode being contaminated or covered. Use the 2V DC range of a digital multimeter to measure the polarization voltage between the two electrodes and the ground (the electromagnetic flowmeter can be measured without power outage or without power outage). If the two measurement values ​​are close to almost equal, it means that the electrode is not contaminated or covered, otherwise it means that the electrode is contaminated or covered. The size of the polarization voltage depends on the "electrode potential" of the electrode material and the properties of the liquid. The measured value may range from a few mV to hundreds of mV. Because in fact, the contamination conditions of the two electrodes during operation cannot be the same and symmetrical, so the voltages on the two electrodes form an asymmetric common mode voltage. The asymmetric common-mode voltage becomes a differential-mode signal, causing a zero offset. Only by mastering this knowledge can we find the cause of the instrument failure. Next, we will talk about how to find instrument problems by measuring the dislocation ground potential. For example, if the state of the electric (power) machine near the sensor changes (such as leakage), the ground potential will change and cause the zero point to change. To check whether this is affected, you can short-circuit the converter's working ground C terminal and protective ground G terminal, and use the zero point (or indicated value) change to determine whether there is a ground potential. Time to identify the direction of stray current in pipelinesIn order to find the source of stray interference in the pipeline, it is enough to be upstream or downstream of the flow sensor to narrow the search range and try to reduce or eliminate the influence of stray current interference. Although the electromagnetic flowmeter has relatively good reliability and will not be damaged under normal circumstances, due to its principle, the sensor electrode surface is always in contact with the liquid. Over time, the electrode surface is more susceptible to contamination. Therefore, under normal circumstances, if the customer has the conditions to dismantle the electromagnetic flowmeter, it is recommended to disassemble it and clean the electrodes once every one to one and a half years to ensure the measurement accuracy of the entire flowmeter. Any instrument requires "maintenance", and electromagnetic flowmeters are no exception.