First, the meter has no flow signal output
1. Reasons analysis
This type of failure is common during use. The reasons are generally as follows:
(1) abnormal power supply of instruments;
(2) abnormal cable connection;
(3) The liquid flow condition does not meet the installation requirements;
(4) Damage to sensor components or measurement of the inner wall with a adhesive layer;
(5) Damage to the parts of the converter.
2. Solutions
(1) Verify that the power supply is connected, check that the output voltage of the power circuit board is normal, or try to replace the entire power circuit board to determine whether it is good or bad.
(2) Check that the cable is intact and properly connected.
(3) Check the direction of liquid flow and whether the liquid in the pipeline is full. For electromagnetic flowmeters that can be measured in positive and negative directions, if the directions are inconsistent, they can be measured, but the set display direction is inconsistent and must be corrected. If you need a lot of work to remove the sensor, you can change the direction of the arrow on the sensor and reset the display instrument symbol. The unfilled liquid in the pipeline is mainly due to the improper installation of the sensor. Measures should be taken during installation to avoid causing liquid dissatisfaction in the pipeline.
(4) Check whether the electrode on the inner wall of the transmitter is covered with a liquid scar layer and regularly clean the measurement fluid that is prone to scars.
(5) If the fault is determined to be caused by damage to the converter component, the damaged component may be replaced.
Volatility of output values
1. Reasons analysis
Most of these failures are caused by the influence of the measuring medium or the external environment. After removing external interference, you can eliminate the failure yourself. In order to ensure the accuracy of the measurement, this kind of fault can not be ignored. In some production environments, the circuit board of the flowmeter will loosen due to the vibration of the measuring tube or liquid, and the output value may fluctuate.
2. Solutions
(1) Determine whether the fluid pulsates due to process operation. At this point, the flowmeter can only truly reflect the flow situation, and can eliminate the failure after pulsating.
(2) Electromagnetic interference caused by external stray currents, etc.. Check the working environment of the instrument for large electrical appliances or welding machines. Ensure the instrument is grounded and operated in a good environment.
(3) When the pipe is not filled with liquids or bubbles in the liquid, it is caused by technical reasons. At this point, the process personnel can be required to confirm that the output value can return to normal after the liquid filling pipe or bubble level.
(4) The transmitter circuit board is a plug-in structure. Due to the large vibration of the field measurement pipe or liquid, it often leads to the loosening of the flowmeter power plate. If loose, you can remove the flowmeter and reset the circuit board.
III. Inconsistency of flow measurement with actual values
1. Reasons analysis
(1) Whether the transmitter circuit board is intact;
(2) When the liquid flow rate is too low, there are tiny bubbles in the tested liquid. When the bubbles rise and gradually accumulate above the pipeline, the liquid flow area changes, and when the gas is sufficient, interference signals will be generated, affecting the measurement accuracy;
(3) Poor signal cable connections or poor insulation performance during the use of the cable lead to inaccurate measurement;
(4) The parameter setting of the converter is not accurate.
2. Solutions
(1) Check that the transmitter circuit board is intact. If the junction box is full of water or corrosive liquid corrosion, electrical properties may be reduced or damaged. The circuit board should be replaced at this time.
(2) Ensure that the liquid flow measured in the pipeline is higher than the minimum flow limit so that the transmitter can work properly.
(3) Check the integrity of the signal wire connection and cable insulation. If the signal is loose, please reconnect; If it is found that the insulation of the cable does not meet the insulation requirements, the cable needs to be replaced.
(4) Reset the converter's settings and check the converter's zero and full values.