Electromagnetic flowmeters find problems by measuring electrical contact resistance: electricity is the core component of the flowmeter and is used to measure the signal generated by the liquid medium.
A brief analysis of the problems and solutions of electromagnetic flowmeters measuring electrical contact resistance:
Do you know what the fault phenomena of electromagnetic flowmeters 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? Electromagnetic flowmeters are flow meters with high precision, high reliability and long service life. Therefore, we pay great attention to every link in the process of product structure design, 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. Under normal circumstances, 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.
Electromagnetic flowmeters find problems by measuring electrical contact resistance: electricity is the core component of the flowmeter and is used to measure the signal generated by the liquid medium. Electrical contact resistance measurement measures the liquid contact resistance value of the electric spoon. It is possible to indirectly estimate the general condition of the flow sensor and lining surface without removing the flow sensor from the pipeline, which is helpful for analyzing the cause of the failure. Measuring the voltage between electricity and liquid will help determine whether the zero point instability or output shaking fault is caused by the electricity being contaminated or covered. Use the 2V DC range of a digital multimeter to measure the voltage between the two voltages and the ground (the electromagnetic flowmeter can be measured without power interruption or power failure). If the two measurement values are close to almost equal, it means that the electricity is not contaminated or covered, otherwise it means that the electricity is contaminated or covered. The magnitude of the voltage depends on the "electrical potential" of the electrical material and the properties of the liquid. The measured value may range from a few mV to hundreds of mV. Because in fact, the pollution conditions of the two power supplies during operation cannot be the same and symmetrical, so the voltages on the two power supplies 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 dislocated 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 electrical surface of the sensor is always in contact with the liquid. Over time, the electrical 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 it 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.
Hangzhou Economic Development Area，Hangzhou 310018，China
