Failure in operation of the electromagnetic flowmeter and the solution
The faults in the operation of electromagnetic flowmeter in has two kinds: one is the instrument itself fault, namely the structure or component damage caused as a result of the instrument; 2 it is caused by external causes of failure, such as installing a wrong flow distortion, deposition and scaling, etc. SIKE measurement and control technology co., LTD. In this article are the two types of failure analysis solution.
Classification according to the failure period, can be divided into: ❶ debugging phase fault; ❷ runtime failures. Failure occurs in the early new debugging during commissioning period of the main reason is that the instrument selection or improper setting, installed improperly, etc. Run-time failures in operation after a period, impurity attached electrodes or the lining in the main reasons are fluid, environmental conditions change a new interference sources, etc.
According to the fault outside source analysis from three aspects: (1) pipe system and installation, etc; (2) caused by environment; (3) caused by fluid. Source (1) mainly in the debugging phase; Source (2) and (3) will appear in commissioning period and operation period.
1, instrument no flow signal output
Cause analysis,
This kind of failure is common in use process, because generally have: (1) the instrument power supply not normal; (2) the cable connection is not normal; (3) the liquid flow conditions do not conform to the requirements of the installation; (4) sensor components damaged or measuring wall adhesion layer; (5) converter damage of components.
The solution
(1) confirm having access to the power supply, check the power supply circuit board output various voltage is normal, or try to replace the power supply circuit board, judging its quality.
(2) check whether the cable is in good condition, connection is correct.
(3) check whether the fluid and tube filled with liquid flow direction. To be positive and negative to the measurement of the electromagnetic flowmeter, if inconsistent direction is measurable, but does not set the display of the flow of positive and negative direction, must be corrected. If the sensor workload big, also can change the direction of the arrow on the sensor and reset the display instrument symbols. Pipe flow not filled with liquid is mainly caused by improper sensor installation location, should take measures when installation, avoid to cause pipeline fluid in pipe.
(4) check the inner electrode layer is covered with the liquid scarring in the transmitter, for measuring the liquid easy to scar, regularly to clean up.
(5) if the judgment is for converter component damage caused by fault, replace the damaged components.
2, the output value
Cause analysis,
Cause such failures are mostly by measuring medium or of the influence of the external environment, after the interference ruled out fault can eliminate itself. In order to ensure the precision of measurement, such failures also cannot be ignored. In some production environments, due to the vibration of the measuring pipe or liquid is big, will cause the flow meter of circuit board is loose, also can cause fluctuations in the output value.
The solution
Ⅰ. Confirm if reason for process operation, fluid were indeed pulsation, the meter only reflect flow, pulsating after failure can eliminate itself.
Ⅱ. Outside electromagnetic interference from stray current. Check the meter running environment for large electronics or electric welding machine in work, want to confirm that the instrument grounding and running environment is good.
Ⅲ. Piping is not filled with liquid or liquid containing bubbles, both for process reasons. Can request technical personnel confirmed at this time, after being calm liquid filled tube or bubbles, the output value can be back to normal.
Ⅳ. Transmitter circuit board for the plug-in structure, as a result of field measurement or liquid pipe vibration is big, often caused by the power of the flowmeter plate is loose. Such as loose, flow meter can be disassembled to fixed circuit board.
3, the flow measurement value does not accord with the actual value
Cause analysis,
Transmitter circuit boards are in good condition; (2) when the liquid flow rate is too low, the tiny air bubbles in the liquid being measured, the bubble rising gradually gathered over the pipe, the liquid circulation area changes, gas long will produce interference signals, affect measurement accuracy. (3) the signal cable connection is not good phenomenon or cable insulation performance degradation in use process cause inaccurate measurement; (4) the parameter setting of the converter is not accurate.
The solution
I check the transmitter circuit board are in good condition. If the junction box into the water or corrosive liquid corrosion under test, which can lead to electrical performance degradation or damage. A circuit board should be replaced at this time.
II ensure the measured velocity of liquid in the pipe at the lowest flow above the threshold value, so that the transmitter can work normally.
III check signal cable connection and the insulation of the cable is in good condition, if appear signal cable loose phenomenon, reconnect it can; If the check to the cable insulation do not conform to the requirements of the insulation, you need to change a new cable.
Iv to set of converter set value, and to calibrate the zero, the full value of converter.
4, output signal full range
Cause analysis,
The causes of such failure to roughly: (1) the signal cable connection errors or cable connection is broken; (2) the parameters of the converter set is not correct; (3) converter models don't match with the sensor.
The solution
(1) check the signal circuit connection is normal or not, if the signal circuit disconnect, the output signal will be super full value, should be properly connected signal cable anew at this time. At the same time, need to check whether the insulation of the cable in good condition, if have do not conform to the requirements, the need to change a new cable.
(2) the parameters of the detailed check converter set and zero and full compliance with requirements.
(3) the check to the converter and sensor models don't match, you will need to contact the manufacturer change.
5, unstable zero
Cause analysis,
(1) pipe is not filled with liquid or liquid containing bubbles.
(2) evaluate pumps liquid pipe flow as small flow and actually exist.
(3) the liquid (such as liquid conductivity poor uniformity, electrode pollution, etc.).
(4) signal circuit insulation.
The solution
(1) pipe is not filled with liquid or liquid containing bubbles are for technology reason, at this time should be confirmation request technology personnel, process after normal, the output value can be back to normal.
(2) pipes with trace flow, this is not a fault electromagnetic flowmeter.
(3) if the sediment measurement of pipe wall or on the inner wall of the measuring tube fouling, or electrode contamination, all have zero changes may occur, this time must be clean; If zero little change, also can try to zero.
(4) due to the effect of environmental conditions, such as dust, oil may enter the watch case body, therefore, whether or not the parts need to check the electrode insulation down or damaged, if do not conform to the requirements of the insulation, it must be cleaned up.