Only need to make periodic visual inspection of the instrument, check the surrounding environment of the instrument, sweep dust, ensure that there is no water and other substances, check whether the wiring is good, check whether there is new equipment with strong electromagnetic field near the instrument, or there is a newly installed wire across the instrument.
If the measuring medium is easy to contaminate the electrode or in the measurement of the wall sedimentation, scaling, should be regularly cleaned, cleaned.
2, fault finding
After the meter has been put into operation or normal operation for a period of time, it is found that the instrument is not working properly. First, check the external condition of the flowmeter, such as whether the power supply is good, if the pipe is leaked or is not in a full-pipe state, if there is air bubble in the pipe, and if the signal cable is Damaged, converter output signal (ie, the rear instrument input circuit) is open. Remember to blindly remove the flowmeter.
3, sensor inspection
Test equipment: 500MΩ insulation resistance tester, a multimeter.
Test steps:
(1) When the pipeline is full of media, use a multimeter to measure the resistance between terminals A, B, and C. The resistance between AC and BC should be large. If the difference is more than 1 time, it may be the leakage of the electrode, the measurement of the outer wall of the tube or the adsorption of condensed water in the junction box.
(2) When the liner is dry, use MΩ meter to measure the insulation resistance between AC and BC (should be greater than 200MΩ). Then use a multimeter to measure the resistance of the two terminals in the terminals A, B and the measuring tube (should be short-circuit connected). If the insulation resistance is very small, indicating electrode leakage, the entire flowmeter should be returned to the factory for repair. If the insulation is reduced but there 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 interior of the housing may be dried by a hot air blower.
(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 have poor contact. Remove the terminal board check.
(4) Check that the insulation resistance between X, Y and C should be more than 200 MΩ. If there is a decrease, use a hot air to dry the inside of the housing. In actual operation, a decrease in coil insulation will lead to an increase in measurement error and an unstable output signal of the instrument.
(5) If it is determined that the sensor is faulty, please contact the manufacturer of the electromagnetic flowmeter. Generally, it cannot be solved on the spot and it is necessary to repair it.
4, converter check
If it is determined that the converter is faulty and the external cause is no problem, please contact the manufacturer of the electromagnetic flowmeter. The manufacturer usually adopts the method of replacing the circuit board.