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1. Fault diagnosis: When a flow meter starts operating or has been in normal operation for some time and then begins to function improperly, it is necessary to first check the external conditions of the flow meter – such as whether the power supply is functioning properly, whether there are leaks in the pipes or if they are not fully filled, whether there are bubbles inside the pipes, whether the signal cable is damaged, and whether the output signal from the converter (i.e., the input circuit for the downstream instruments) is open-circuited. Be sure not to disassemble the flow meter blindly. 2. Sensor inspection: Testing equipment: one 500MΩ insulation resistance tester and one multimeter. 3. Routine maintenance: It is only necessary to conduct periodic visual inspections of the instruments, check the environment surrounding them, remove dust and dirt, ensure that no water or other substances get in, verify that the wiring is in good condition, and check whether there are any newly installed devices that generate strong electromagnetic fields nearby or new wires running across the instruments. If the medium being measured tends to contaminate the electrodes or precipitate and form scale inside the measurement tube, cleaning and descaling should be carried out regularly. Testing steps: (1) With the lining dry, use a MΩ meter to measure the insulation resistance between A-C and B-C (it should be greater than 200 MΩ). Then use a multimeter to measure the resistance between terminals A and B and the two electrodes inside the measuring tube (they should be in a short-circuited state). If the insulation resistance is very low, it indicates electrode leakage, and the entire flow meter should be returned to the factory for repair. If the insulation level has decreased but remains above 50 MΩ and the results of step (1) are normal, it may be that the outer wall of the measuring tube is damp; in such cases, a heat blower can be used to dry the interior of the enclosure. (2) Use a multimeter to measure the resistance between X and Y; if it exceeds 200Ω, the excitation coil and its leads may be open-circuited or have poor contact. Remove the terminal block for inspection. (3) Check the insulation resistance between X, Y, and C; it should be above 200 MΩ. If it decreases, dry the interior of the enclosure using hot air. During actual operation, a decrease in the insulation of the coils will lead to increased measurement errors and unstable output signals from the instrument. (4) When the pipeline is filled with fluid, use a multimeter to measure the resistance values between terminals A, B, and C; the resistance values between A-C and B-C should be roughly equal. If the difference is more than 1 times, it may be due to leakage at the electrode, or the presence of condensed water adhering to the outer wall of the measurement tube or inside the junction box.