Intelligent electromagnetic flowmeter will produce some faults in the process of use, which will affect the normal operation of the instrument. How to find the reason behind the fault is a very important task. We need to identify through various types of detection methods. Under normal circumstances, we routinely check the electromagnetic flowmeter, usually including the electrode contact resistance, the polarization voltage of the electrode, the interference of the signal cable, and the determination of the ground potential and the stray current flow of the pipe. These five aspects can be individually In fact, they are also related to each other. Changes in any one factor may cause changes in other vendors. This reminds everyone to pay special attention when testing:
Intelligent electromagnetic flowmeter First, the electrode contact resistance measurement measurement, the electrode and the liquid contact resistance value, can estimate the juice electrode and the surface condition of the liner layer indirectly without unloading the flow sensor from the pipeline, help to analyze the cause of the fault.
Measuring the contact resistance of the electrode and the liquid can indirectly evaluate the general condition of the surface of the electrode and the lining layer without removing the flow sensor from the pipe, which is helpful for analyzing the cause of the failure. In particular, the inspection of large-diameter electromagnetic flowmeters is greatly facilitated. This method can be used to estimate the internal surface conditions of the flow sensor measuring tube, such as whether the electrode and the liner layer are deposited, whether the deposited layer is conductive or insulating, and the surface contamination of the electrode.
Second, the polarization of the electrode voltage measurement Polarization voltage between the electrode and the liquid will help determine whether the zero point instability or output sloshing caused by the electrode is contaminated or covered. With a digital multimeter 2V DC gear, measure the polarization voltage between the two electrodes and the ground (the electromagnetic flowmeter can be measured without interruption or blackout). If the two measurements are nearly equal, the electrode is not contaminated or covered, otherwise the electrode is contaminated or covered. The magnitude of the polarization voltage is determined by the "electrode potential" of the electrode material and the nature of the liquid. The measured value may be between a few mV and a few hundred mV. Because the two electrodes are actually contaminated during operation, it is not possible to be completely symmetrical, so the voltage across the two electrodes forms an asymmetric common-mode voltage. The asymmetric common-mode voltage becomes a differential mode signal, causing a zero offset.
Third, the determination of signal cable interference Signal cable by the external electrostatic induction and electromagnetic induction interference will make electromagnetic flowmeter zero changes. To determine whether the zero point change is due to signal cable interference potential influences, it is necessary to determine the general scope of the interference and the degree of influence on the electromagnetic flowmeter.
Fourth, determine whether the ground potential electromagnetic flow juice in the normal use of the process, such as the sensor near the electric (force) machine status changes (such as leakage), ground potential will change and cause zero changes. Check if there is any influence in this way. Short circuit the converter's working ground C terminal and protective grounding G terminal, and judge whether there is a grounding potential by changing the zero point (or indication value).
V. Distinguishing the stray current flow of the pipeline Sometimes the disturbance source for finding the spurious of the pipeline is still at the downstream of the flow sensor to narrow down the search range and try to reduce or eliminate the influence of stray current interference.
Intelligent electromagnetic flowmeter
Intelligent electromagnetic flowmeter First, the electrode contact resistance measurement measurement, the electrode and the liquid contact resistance value, can estimate the juice electrode and the surface condition of the liner layer indirectly without unloading the flow sensor from the pipeline, help to analyze the cause of the fault.
Measuring the contact resistance of the electrode and the liquid can indirectly evaluate the general condition of the surface of the electrode and the lining layer without removing the flow sensor from the pipe, which is helpful for analyzing the cause of the failure. In particular, the inspection of large-diameter electromagnetic flowmeters is greatly facilitated. This method can be used to estimate the internal surface conditions of the flow sensor measuring tube, such as whether the electrode and the liner layer are deposited, whether the deposited layer is conductive or insulating, and the surface contamination of the electrode.
Second, the polarization of the electrode voltage measurement Polarization voltage between the electrode and the liquid will help determine whether the zero point instability or output sloshing caused by the electrode is contaminated or covered. With a digital multimeter 2V DC gear, measure the polarization voltage between the two electrodes and the ground (the electromagnetic flowmeter can be measured without interruption or blackout). If the two measurements are nearly equal, the electrode is not contaminated or covered, otherwise the electrode is contaminated or covered. The magnitude of the polarization voltage is determined by the "electrode potential" of the electrode material and the nature of the liquid. The measured value may be between a few mV and a few hundred mV. Because the two electrodes are actually contaminated during operation, it is not possible to be completely symmetrical, so the voltage across the two electrodes forms an asymmetric common-mode voltage. The asymmetric common-mode voltage becomes a differential mode signal, causing a zero offset.
Third, the determination of signal cable interference Signal cable by the external electrostatic induction and electromagnetic induction interference will make electromagnetic flowmeter zero changes. To determine whether the zero point change is due to signal cable interference potential influences, it is necessary to determine the general scope of the interference and the degree of influence on the electromagnetic flowmeter.
Fourth, determine whether the ground potential electromagnetic flow juice in the normal use of the process, such as the sensor near the electric (force) machine status changes (such as leakage), ground potential will change and cause zero changes. Check if there is any influence in this way. Short circuit the converter's working ground C terminal and protective grounding G terminal, and judge whether there is a grounding potential by changing the zero point (or indication value).
V. Distinguishing the stray current flow of the pipeline Sometimes the disturbance source for finding the spurious of the pipeline is still at the downstream of the flow sensor to narrow down the search range and try to reduce or eliminate the influence of stray current interference.
Intelligent electromagnetic flowmeter
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