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1. Determine whether the cause of the fault lies before the electromagnetic flowmeter converter or in the downstream instruments after the converter. Check item 1 of the procedure. The fault is before the converter, that is, in the signal cable between the sensor and the sensor/converter (the signal connection cable of integrated electromagnetic flowmeters; faults occur very rarely inside the instrument) ； Next are the sensor itself, along with lower-level instruments such as accumulators or flow computers that follow it. First, fill the piping system and flow sensor with water. With no flow present, short-circuit the two signal terminals of the converter along with its functional or protective terminals, and check whether the output signal of the converter drops to zero. If it can be reduced to zero, it can be preliminarily inferred that the fault lies prior to the conversion process, rather than in the converter itself or the instruments downstream; as the next step, the connection cables and sensors should be checked first ； If it cannot be reduced to zero, check that the center of gravity should be at the converter and the rear instrument. 2. Verify the integrity of the signal cable and ensure full contact between the two electrode fields and the liquid. Check item 2 of the process. If the signal circuit is disconnected, the output signal will exceed the full-scale value; therefore, the purpose of this check is to verify that the flow signal circuit is intact and unobstructed. The signal circuit includes the cable and its connection terminals, as well as a flow sensor’s pair of electrodes and the liquid between them. In addition to checking the continuity of the circuit, it is also necessary to verify the cable model, the correctness of connections at each joint, and whether the insulation meets the required standards. The electrodes of the flow sensor are not in contact with the liquid (either both electrodes are not in contact with the liquid, or one electrode is not in contact; in such cases the signal cable is also disconnected). It is necessary to modify the flow sensor so that it can be placed in a position where it is fully submerged in liquid, in order to eliminate the issue of the electrodes not being in contact with the liquid. 3. Verify the correctness of the converter setting values, and check the zero and full-scale points. Item 3 of the inspection process. When a separate-type electromagnetic flowmeter leaves the factory, the converter and sensor are typically calibrated with actual flow rates according to the specified diameter, flow rate, and setting parameters as outlined in the contract, and the sensor and converter must correspond to each other one-to-one. Therefore, first check whether the accessories are correct, and then verify whether the converter’s instrument constants and various parameters are appropriate. Then use the analog signal generator to check the zero point again. For integrated instruments, there is no need to check this item. 4. Check the rear instrument panel. Step 4 of the inspection process. The flow signal output by the electromagnetic flowmeter converter is transmitted to downstream instruments such as flow integrators and flow computers. If the rear instrument panel is connected electrically (i.e., it constitutes an active load), the power feedback from this load can damage the converter’s output circuit, resulting in signal levels exceeding the maximum allowable values; in such cases, electrical isolation measures must be taken. The converter output circuit comes in two types: grounded and ungrounded. If grounding is permitted, the output still exceeds the full-scale value; the converter is faulty ； If accidental grounding by those not allowed to do so is prevented, normal operation can be achieved simply by removing the ground connection. 5. Check for electrical interference introduced from the liquid. Refer to item 5 in the inspection flowchart. In the absence of excitation current, the interference potential is measured at the two electrodes using a multimeter or an oscilloscope. This fault phenomenon often occurs in processes such as sodium chloride electrolysis in the alkali industry, as well as on cathodic protection pipelines. A solution is to insulate the electromagnetic flow sensor from the pipeline, thereby keeping the electrode at the same potential as the liquid. 6. Check the converter itself. The reasons for the output signal exceeding its full-scale value due to faults in the electromagnetic flowmeter converter itself are complex; such issues can be caused by a problem in one of the various circuits within the converter, and the differences depend largely on the type of converter (analog or digital). For general users ； The circuit boards of modern electromagnetic flowmeters can be divided into interchangeable and independent units; replacement testing can be carried out by trying alternative circuit boards (or temporarily borrowing circuit boards from other instruments of the same model that are operating properly) to conduct inspections and diagnoses. First, check item 6 of the process, that is, inspect the input/output circuits. Based on the respective characteristics of analog circuit converters and digital circuit converters, several key aspects are examined; for analog circuit converters, the focus is on whether the feedback loop is open-circuited and whether there is any damage to the output circuit ； For digital circuit converters, the main inspection aspects should be analyzed from the ND conversion circuit and the output circuit. For more information, please visit the company’s official website at http://www.yb1518.com/. 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