Wastewater electromagnetic flowmeter common problems faults and solutions

Case introduction

　　First, the sewage flowmeter no flow output 1, cause analysis This type of failure is more common in the use of process, the reasons are generally: (1) the instrument power supply is not normal; (2) the cable connection is not normal; (3) the media flow conditions do not meet the installation requirements; (4) sensor parts damaged or lined with an adherent layer; (5) the converter components are damaged. 2, the solution (1) to confirm that has been connected to a person's power supply, check power supply Check whether the output voltage of the circuit board is normal, or try to replace the entire power supply circuit board to determine whether it is good or bad. (2) Check whether the cable is intact, connected correctly. (3) Check the measured medium flow direction and whether the tube is full of media. For positive and negative measurement of sewage flowmeter, if the direction is inconsistent although you can measure, but set the display flow rate positive and negative direction does not match, must be corrected. If the removal of the sensor workload, you can also change the direction of the arrow on the sensor and reset the display instrument symbols. Pipeline is not full of media is mainly caused by the sensor installation location is not appropriate, should take measures in the installation, installation requirements in strict accordance with the installation, to avoid causing the pipeline medium is not full of pipe. (4) Check whether the transmitter inner wall electrode is covered with medium scarring layer, for easy scarring of the measurement medium, to be cleaned regularly. (5) If the judgement is the fault caused by damage to the converter components, replace the damaged components can be.

　　Second, the output value fluctuations 1, cause analysis caused by such failures are mostly caused by the measurement medium or the influence of the external environment, such as strong magnetic fields, strong electromagnetic waves so the installation is generally noted to be away from strong magnetic fields. Sewage flowmeter should meet the requirements of electromagnetic compatibility, in the provisions of the radiation electromagnetic field environment for normal operation, will not be in the environment caused by the instrument performance degradation or work abnormally. In addition strong radio waves and stray currents on the pipeline may also become a source of interference. The fault can be eliminated by itself after the external interference is eliminated. In order to ensure the accuracy of the measurement, such failures should not be ignored. In some production environments, due to the measurement of pipeline or liquid vibration, will cause the flowmeter circuit board loose, can also cause fluctuations in the output value. 2, the solution (1) to confirm whether or not the reason for the operation of the process personnel, the fluid does pulsation, this time the flowmeter is only truthfully reflecting the flow conditions, pulsation end of the fault can be eliminated on its own. (2) external current and other electromagnetic interference. Check whether the instrument operating environment of large electrical appliances or welding machine at work, to confirm the instrument grounding and good operating environment. (3) Sewage flow meter properly grounded, you can avoid the pipeline the vast majority of stray current. (4) The pipeline is not filled with the measured liquid or liquid containing air bubbles, both caused by process reasons. At this time, you can ask the process personnel to confirm that the liquid to be full of pipe or bubble calming, the output value can return to normal. (5) transmitter circuit board for the plug-in structure, due to the field measurement of pipeline or liquid vibration, often caused by the flowmeter power board loose. If loose, the flowmeter transmitter can be disassembled, re-fixed circuit board.

　　Third, the sewage flowmeter values do not match the actual value 1, cause analysis (1) transmitter circuit board is intact; (2) when the liquid flow rate is too low, the measured liquid contains tiny bubbles, bubbles rise in the pipeline above the gradual aggregation of the liquid circulation area changes, the gas is more than one will also produce interference signals, affecting the accuracy of the measurement; 0) signal cable connection phenomenon or the use of the cable in the process of bad Insulation degradation caused by inaccurate measurement; (4) inaccurate parameter settings of the converter. 2, the solution (1) check whether the transmitter circuit board is intact. If the junction box into the water or corrosive measured liquid corrosion, can lead to electrical performance decline or damage. At this time, the circuit board should be replaced. (2) Ensure that the flow rate of the measured liquid in the pipeline is above the lower flow rate threshold, so that the transmitter can work properly. (3) Check whether the signal cable connection and cable insulation is intact, if there is a signal cable loose phenomenon, will be reconnected can be; if you check to the cable insulation}sheng does not meet the insulation requirements, you need to change the new cable. (4) Re-set the converter set value, and the zero point of the converter, the fullness value of the calibration.

　　Fourth, the sewage flowmeter output signal exceeds the fullness range 1, cause analysis of the causes of such failures are: (1) signal cable wiring errors or cable connection disconnection; (2) the converter parameters are not set correctly; (3) the converter and the sensor model mismatch. 2, the solution (1) to check the signal circuit connection is normal, if the signal circuit is disconnected, the output signal will be exceeded the fullness of the value, this time you need to If the signal circuit is disconnected, the output signal will exceed the fullness value, then it is necessary to reconnect the signal cable correctly. At the same time, need to check whether the insulation of the cable is intact, if it is not in line with the requirements, it is necessary to replace the new cable. (2) Detailed inspection of the sewage flowmeter converter parameter settings and zero, fullness is in line with the requirements. (3) check to the converter and sensor model mismatch, then you need to contact the factory to switch.

　　Five, the zero point is not stable 1, cause analysis (1) the pipe is not full of liquid or liquid containing air bubbles. (2) subjectively that the tube pump liquid no flow and in fact there is a small flow. (3) Liquid (such as liquid conductivity uniformity is not good, electrode contamination, etc.) reasons. (4) Water in the terminal box or moisture in the excitation coil, so that the insulation of the excitation coil circuit to the ground is reduced. 2, the solution (1) The pipeline is not full of liquid or liquid containing air bubbles are process reasons, at this time, should be requested to confirm the process personnel, process normal, the output value can be restored to normal. (2) There is a trace of flow in the pipeline, which is not a sewage flowmeter failure. (3) If the impurities deposited on the inside wall of the measuring tube or in the measurement of the inner wall of the tube scale, or electrode contamination, there may be a zero change, this time must be cleaned; if the zero change is not large, you can also try to re-zero. (4) Due to the influence of environmental conditions, water, dust, oil, etc. may enter the terminal box, therefore, it is necessary to check whether the electrode part of the insulation is declined or damaged, if it does not meet the insulation requirements, it must be cleaned.