What are the breakdowns and treatment measures of electromagnetic flowmeters?

The smart converter and the electromagnetic flow sensor together form an electromagnetic flowmeter to measure the flow rate. Therefore, before handling the converter failure, please confirm that the flow state of the pipeline fluid, sensors, and system wiring are normal!

No display

a) Check if the power is on;

b) Check if the power fuse is in good condition and the replacement of the fuse should be of the same model specification;

c) Check whether the supply voltage meets the requirements;

d) Check if the display contrast adjustment can be adjusted and the adjustment is appropriate;

e) If the above three items a), b), c) are all normal, f) When no problem is found, please send the converter to the manufacturer for repair.

Excitation alarm

a) Is the excitation wiring EX1 and EX2 open?

b) The total resistance of the sensor excitation coil should be less than 150Ω;

c) If both a) and b) are normal, the converter is faulty.

Empty tube and electrode alarm

a) Measuring whether the fluid is full of sensor measuring tubes;

b) Short the three points of the converter signal input terminals SIG1, SIG2 and SIG GND with wires. If “empty tube alarm” and “electrode abnormality” prompt to withdraw at this time, it means that the converter is normal and the measured fluid may have low conductivity. Or the electrode is covered by gas.

c) Check that the signal connection is correct;

d) Electrode abnormality If the sensor is full of fluid, use a 500-meter analog multimeter, resistance × 1 kΩ, and check the sensor electrode resistance. The red test leads of the universal meter are connected to the electrodes respectively, the black test leads are connected to the liquid electrode (liquid ring or metal pipe), the pointer of the universal meter swings from left to right, indicates about 3~50kΩ, and then goes from right to left Discharge, the difference between the two electrodes swinging to the right does not exceed 20%, otherwise the electrode is contaminated and covered. Use a digital multimeter to measure the DC voltage between the DS1 and DS2 butt fluid points (liquid contact electrode, liquid ring, and metal pipe) to be less than 1V. The DC voltage difference between the two electrodes should be less than 50mV. Otherwise, the sensor electrode is polarized. The upper alarm limit alarm indicates that the output current and output frequency (or pulse) are out of limits. Increasing the flow range can remove the upper limit alarm. Lower limit alarm The lower limit alarm indicates that the output current and output frequency (or pulse) are out of limits. Lowering the flow range can undo the lower limit alarm. System setting errors Intelligent judgments and prompts have been made in the flow range settings, flow totalizer settings, and pulse equivalent settings to facilitate modification of settings. System self-test alarm, if the system self-test alarm, please turn the converter to the factory for maintenance.

Inaccurate measured flow

a) Whether the fluid to be measured is filled with the sensor measuring tube and whether there are air bubbles in the pipe;

b) Is the signal line connection normal, whether the insulation is lowered, and whether the ground connection is good?

c) Check whether the sensor coefficient, sensor zero, and factory calibration coefficient are set correctly according to the sensor label or factory calibration sheet;

d) Check the sensor electrode and liquid contact resistance and electrode insulation is good.

Communication failure check

a) The 232/485 conversion interface does not perform well. The conversion interface performance of different manufacturers varies greatly.

b) The communication line material is not good. Must be a shielded twisted pair, if it is a common parallel line, because of the influence of distributed capacitance, the transmission distance will not be too far, the transmission speed will not go up.

c) The communication line is in the wrong position or the communication line is reversed.

d) The instrument's instrument address, baud rate, and settings in the meter are not the same.

e) The protocol is incorrect. Some protocols send two-byte commands, and some protocols send 4-byte commands.

f) communication is over 1000 meters, or electromagnetic field too much interference, this time should be increased to increase the communication relay transmission capacity.

g) When testing in the field, it is best to use a computer to connect directly to the instrument through a short cable. This eliminates many factors such as wire and environmental electromagnetic interference. It can quickly determine the 232/485 interface, wiring, or communication protocol.

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