How to better maintain the electromagnetic flowmeter
Electromagnetic flowmeter in use, we need to pay attention to what? Today for you to do a simple description, I hope you pay attention to the following points about the maintenance of electromagnetic flowmeters:
1. Daily maintenance
Only periodic visual inspection of the instrument, check the environment around the instrument, clean the dirt, ensure that there is no water and other substances, check whether the wiring is good, check whether there is a new strong electromagnetic field equipment near the instrument or a new wire across the instrument.
2. Fault search
After the electromagnetic flowmeter is put into operation or normal operation for a period of time, it is found that the meter is not working normally, and the external situation of the flowmeter should be checked first, such as whether the power supply is good, whether the pipeline leaks or is in a non-full pipe state, whether there are bubbles in the pipeline, whether the signal cable is damaged, and whether the output signal of the converter is open. Remember to dismantle flowmeters blindly.
3, sensor inspection
Test equipment: one 500MΩ insulation resistance tester, one multimeter.
Test steps:
1) When the pipe is full of media, use A multimeter to measure the resistance between the wiring terminals A, B and C, and the resistance between A-C and B-C should be equal. If the difference is more than 1 times, there may be leakage of the electrode, condensate adsorption in the outer wall of the measuring tube or the junction box.
2) When the lining is dry, use an MΩ meter to measure the insulation resistance between A-C and B-C (should be greater than 200MΩ). Then use A multimeter to measure the resistance between terminals A and B and the two electrodes in the measuring tube (the connection should be short circuit). If the insulation resistance is small, it indicates that the electrode is leaking, and the whole flowmeter should be returned to the factory for maintenance. If the insulation has decreased but is still more than 50MΩ and the inspection result of step (1) is normal, the outer wall of the measuring tube may be damp, and the inside of the housing can be dried by a hot fan.
3) Use a multimeter to measure the resistance between X and Y. If the resistance exceeds 200Ω, the excitation coil and its lead wire may be open or in poor contact. Remove the terminal board and check.
4) Check the insulation resistance between X, Y and C, should be more than 200MΩ, if it drops, use hot air to dry the inside of the shell. In actual operation, the decrease of coil insulation will lead to the increase of measurement error and the instability of instrument output signal.
