Electromagnetic water meters, as the core equipment in the field of flow measurement, are widely used in urban water supply, industrial circulating water, and agricultural irrigation scenarios due to their high precision, wide range, and low pressure loss characteristics. This article takes common electromagnetic water meter products as an example to analyze their technical principles and provide daily maintenance suggestions.

1、 Working principle of electromagnetic water meter: application of Faraday's law of electromagnetic induction

1. Measurement core mechanism

Electromagnetic water meters work based on Faraday's law of electromagnetic induction: when a conductive liquid (such as water) moves at a speedvWhen cutting magnetic field lines vertically, induced electromotive force will be generated on electrodes perpendicular to the magnetic field and flow directionE, its size and fluid velocityvMagnetic field strengthBAnd electrode spacingdDirectly proportional, the formula is:
E = k·B·d·v
（kAs an instrument constant, it is related to the inner diameter of the pipeline

2. structural composition

Measuring tube: non-magnetic material (such as stainless steelPVC）Pipeline, ensure uniform distribution of magnetic field.

Excitation coil: wound around the outer wall of the measuring tube, generating a stable magnetic field through direct current or alternating current.

Electrodes: installed in pairs on both sides of the measuring tube for collecting induced electromotive force signals.

Converter: amplifies, filters, and converts weak electromotive force signals into digital flow values, supporting4-20mAOr pulse signal output.

3. Signal processing flow

The analog signal collected by the electrode is amplified by a preamplifier (gain)100-1000After processing, pass throughA/DThe converter is converted into a digital signal, which is then processed by a microprocessor (such asSTM32Perform temperature compensation, linear correction, and flow calculation for the series, and finally display parameters such as cumulative flow and instantaneous flow.

2、 Key points of daily maintenance: ensuring measurement accuracy and equipment lifespan

1. Regular cleaning and inspection

Electrode cleaning: every3-6Disassemble the electrode every month and wipe the surface attachments (such as scale and rust) with a soft cloth to avoid signal attenuation. If scaling is severe, it can be used5%Soak in dilute hydrochloric acid and clean.

Pipeline troubleshooting: Check whether there is any accumulation of debris (such as sand, gravel, algae) inside the measuring pipe. If necessary, close the valve and disassemble and clean it to prevent measurement errors caused by blocked flow channels.

2. Electrical system maintenance

Wiring Tightening: Check the connection terminals of the converter and sensor quarterly for looseness, with particular attention to the reliability of the excitation coil and electrode signal wires.

Power management: Ensure stable power supply voltage (such as24VDC±10%）To avoid voltage fluctuations that may cause abnormal operation of the converter; equipUPSThe power supply prevents sudden power outages from damaging data.

3. Environmental adaptability adjustment

Moisture and dust prevention: In humid environments (such as underground wells), it is necessary to install protective covers for the converter and regularly use desiccants to remove moisture and prevent short circuits in the circuit board.

Lightning protection grounding: In areas with frequent thunderstorms, the water meter casing and grounding terminal should be reliably grounded (grounding resistance)≤4Ω）To avoid damage to the excitation coil or converter caused by lightning strikes.

4. Regular calibration and verification

Real flow calibration: every1-2Annual real flow calibration is carried out using standard flow devices (such as volumetric method and weighing method) to ensure that the error is within±0.5%Within.

Parameter verification: Check instrument constantskWhether the parameters such as range are consistent with the initial settings to prevent measurement deviation caused by human error modification.

3、 Emergency handling of faults

No display or abnormal data: Check the power supply and wiring. If the power supply is normal, it may be a fault with the converter motherboard and needs to be returned to the factory for repair.

Large flow fluctuation: Check whether there is surge or electrode contamination in the pipeline, and adjust the excitation frequency or replace the electrode if necessary.

Electromagnetic water meters achieve non-contact flow measurement through electromagnetic induction. Enterprises need to combine regular maintenance and fault prediction to ensure long-term stable operation of the equipment and provide reliable data support for water resource management.