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Introduction to the common troubleshooting method of electromagnetic flowmeter

There are two kinds of faults caused by electromagnetic flowmeters in operation:
First, the fault of the meter itself, that is, the fault caused by the damage of the instrument structural component or component;

The second is the failure caused by external causes, such as improper installation of distortion, deposition and scaling. This article discusses these two types of faults.

3. The flow measurement value does not match the actual value. 1. Reason analysis (1) Whether the transmitter circuit board is intact; (2) When the liquid flow rate is too low, the measured liquid contains tiny bubbles, and the bubble rises gradually above the pipeline. , the smooth and smooth liquid area changes, the gas will generate interference signals for a long time, affecting the accuracy of measurement; (3) the signal cable is not well connected or the insulation function of the cable is reduced during use; (4) The parameter settings of the converter are incorrect. 2. Solution (1) Check if the transmitter circuit board is intact. If the junction box is flooded or eroded by the corrosive liquid, the electrical function may be degraded or damaged. The board should be replaced at this time. (2) Ensure that the flow rate of the liquid to be measured in the pipeline is above the minimum flow limit to enable the transmitter to work properly. (3) Check the signal cable connection and the insulation function of the cable. If the signal cable is loose, reconnect it. If the insulation of the cable does not meet the insulation requirements, you need to replace the cable. (4) Re-set the converter set value and check the zero and full scale values of the converter.

Fourth, the output signal super full measurement range 1. Cause analysis caused by such failures are generally: (1) signal cable wiring error or cable connection is disconnected; (2) converter parameter settings are not accurate; (3) The converter does not match the sensor model. 2. Solution (1) Check if the signal loop connection is normal or not. If the signal loop is disconnected, the output signal will be overfull. In this case, the signal cable should be reconnected accurately. At the same time, it is necessary to check whether the insulation function of the cable is intact. If it does not meet the requirements, a new cable needs to be replaced. (2) Specifically check whether the parameter settings of the converter and the zero point and fullness meet the requirements. (3) If it is checked that the model of the converter and the sensor are not matched, you need to contact the factory for exchange.

V. Zero point instability 1. Reason analysis (1) The pipe is not covered with liquid or contains bubbles in the liquid. (2) Subjectively, there is actually little activity in the tube pump liquid. (3) Reasons for liquids (such as poor conductivity of liquid conductivity, electrode contamination, etc.). (4) The signal loop insulation drops. 2. Solution (1) The pipe is not full of liquid or the bubble in the liquid is the process reason. At this time, the process staff should be asked to confirm that the output value can be restored after the process is normal. (2) There is a small amount of activity in the pipeline, which is not a malfunction of the electromagnetic flowmeter. (3) If the impurity deposits on the inner wall of the measuring tube or scales on the inner wall of the measuring tube, or the electrode is contaminated, there may be a zero-point variation. At this time, it is necessary to clean; if the zero point does not change much, try to re-zero. (4) Dust, oil, etc. may enter the watch case due to environmental preconditions.

Therefore, it is necessary to check whether the insulation of the electrode part is reduced or destroyed. If it does not meet the insulation requirements, it must be cleaned. 1. The meter has no flow signal output. 1. Cause Analysis These faults are more common during use. The reasons are generally: (1) The power supply of the instrument is not normal; (2) the cable connection is not normal; (3) the liquid activity does not meet the installation requirements; (4) the sensor components are damaged or the inner wall has an adhesion layer; (5) the converter components are damaged. 2. Solution (1) Confirm that the power supply is connected, check whether the voltage of each output of the power circuit board is normal, or try to replace the entire power circuit board to judge whether it is good or bad. (2) Check if the cable is intact and the connection is accurate. (3) Check the direction of liquid activity and whether the liquid in the tube is full. For electromagnetic flowmeters that can measure forward and reverse, if the direction is inconsistent, it can be measured, but the set display flow rate does not match the positive and negative directions and must be corrected. If the sensor is too large, you can change the direction of the arrow on the sensor and reset the display meter symbol. If the pipeline is not filled with liquid, it is mainly caused by improper installation of the sensor. Measures should be taken during installation to avoid causing the liquid in the pipeline to be unsatisfactory. (4) Check whether the electrode on the inner wall of the transmitter is covered with a liquid crust layer. For the liquid that is easily crusted, it should be cleaned on schedule. (5) If it is determined that the converter component is damaged due to damage, replace the damaged component.

Second, the output value fluctuations 1. Cause analysis Most of these faults are caused by the measurement of the medium or the external environment, and the fault can be eliminated by itself after the external interference is removed. In order to ensure the correctness of the measurement, such failures can not be ignored. In some production environments, the shock of the measuring pipe or liquid can cause the flowmeter's circuit board to loosen, which can also cause fluctuations in the output value. 2. Solution (1) Confirm whether the flow is actually pulsating because of the process control. At this time, the flowmeter only reflects the activity status as it is, and the fault can be eliminated by itself after the pulsation ends. (2) Electromagnetic interference generated by external stray currents. Check whether the instrument is in a working environment with large electrical appliances or welding machines. Make sure that the instrument is grounded and the operating environment is good. (3) When the pipe is not filled with liquid or the bubble contains bubbles, both are caused by process reasons. At this point, the process staff can be convinced that the output value can be restored after the liquid is full or the bubble is recovered. (4) The transmitter circuit board is a plug-in structure. Because the measuring pipe or liquid in the field is shocked, the power supply board of the flow meter is often loosened. If loose, remove the flowmeter and re-fix the board.

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