Daily maintenance and maintenance of electromagnetic flowmeters - Solutions - Huaqiang Electronic Network

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1. Routine Maintenance

It's important to periodically inspect the electromagnetic flowmeter to ensure it’s functioning properly. Check the surrounding environment for any dirt or debris, and make sure there is no water or other substances that could interfere with the readings. Also, verify that the wiring is intact and secure, and look out for any new sources of strong electromagnetic interference or nearby wires that might cross the instrument’s path.

If the medium being measured is prone to contaminating the electrodes or depositing on the inside of the measuring tube, regular cleaning is essential to maintain accuracy and performance.

2. Troubleshooting

If the flowmeter starts to show irregular behavior after installation or after a period of use, begin by checking the external conditions. Confirm that the power supply is stable, the pipeline isn’t leaking, and it’s fully filled with liquid. Look for air bubbles in the pipe and check if the signal cable is damaged. Also, ensure that the converter output (the input loop of the secondary meter) is not open-circuited. Avoid disassembling the flowmeter without proper guidance or knowledge.

3. Sensor Inspection

Tools needed: a 500MΩ insulation resistance tester and a multimeter.

Steps:

(1) When the pipe is full of the medium, use the multimeter to measure the resistance between terminals A, B, and C. The resistance between AC and BC should be equal. If the difference exceeds 100%, there may be an issue with the electrode leakage, condensation on the outer wall, or a problem in the junction box.

(2) In a dry lining condition, measure the insulation resistance between AC and BC using the MΩ meter (it should be above 200MΩ). Then, use the multimeter to check the resistance between the two electrodes at terminals A and B and the measuring tube—this should be in a short-circuit state. If the insulation resistance is low, the electrode may be leaking, and the entire unit should be sent back to the factory for repair. If the insulation is reduced but still above 50MΩ and step (1) shows normal results, the outer wall may be damp. Dry it using a hot air blower.

(3) Use the multimeter to measure the resistance between X and Y. If it exceeds 200Ω, the excitation coil or its wiring may be open or poorly connected. Remove the terminal block to check further.

(4) Check the insulation resistance between X, Y, and C. It should be above 200MΩ. If it drops, dry the inside of the housing with a hot air blower. In practice, a decrease in coil insulation can lead to increased measurement errors and unstable output signals.

(5) If the sensor is found to be faulty, contact the manufacturer of the electromagnetic flowmeter. Most issues cannot be resolved on-site and require professional repair.

4. Converter Check

If the converter is suspected to be faulty, and all external causes have been ruled out, contact the manufacturer of the electromagnetic flowmeter. Typically, the issue will be resolved by replacing the circuit board.