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Description of operation faults of electromagnetic flowmeter

Operation fault of electromagnetic flowmeter
After initial debugging and normal operation, the faults that emerged in the running era after a period of time, the rare causes of failure are: the inner layer of the flow sensor, the lightning strike, and the environmental conditions.
1. Inner wall adhesion layer
Because the electromagnetic flowmeter measures the time of containing suspended solid phase or dirty body much more than the other flow meters, the probability of failure of the emerging inner wall adhesion layer is absolutely higher. If the electrical conductivity of the adhesion layer is close to the liquid conductivity, the instrument can input the signal normally, but only change the flow area, causing a hidden fault of the measurement error; if it is a high conductivity adhesion layer, the electromotive force between the electrodes will be short-circuited; if it is an insulating adhesion layer The electrode surface is insulated to disconnect the measuring circuit. Both of the latter scenes will make the meter unable to perform tasks.
2, lightning strike
Lightning strikes induce high voltage and surge currents in the line, and entering the meter will destroy the meter. The lightning damage meter has three introduction gates: the power line, the flow signal line between the sensor spoon converter and the excitation line. However, from the analysis of the damaged components in the lightning fault, the induced high voltage and surge current caused by the fault are mostly introduced from the power supply line of the master room, and the other two gates are less. It is also understood from the scene of the lightning strike incident that not only the electromagnetic flowmeter has emerged, but also the rest of the instrument in the room often has a lightning strike. Therefore, the application unit should be familiar with the importance of setting up the lightning protection equipment for the instrument room power cord. The current team has been involved in the design team to understand and explore this issue.
3. Changes in environmental conditions
The important cause is the same as the fault environment in the commissioning period of the previous section, except that the source of the disturbance does not emerge during the commissioning period and is re-introduced in the operational era. For example, a grounded shield is not an imaginary electromagnetic flowmeter. During the commissioning period, the instrument is operating normally due to no factory disturbance, but a new disturbance source emerges during the operation period (for example, the measurement point is near the pipeline or the pipeline is welded farther away). Running, the emerging input signal is greatly shaken.

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