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How to improve the anti-interference ability of electromagnetic flowmeter

Electromagnetic flowmeters are mainly used to measure the volumetric flow in conductive liquids and slurries in closed pipes, including highly corrosive liquids such as acids, alkalis and salts. Since the 1950s, it can be said that the history of electromagnetic flowmeters is The development history of anti-jamming technology. Jiangsu Jiujiu Instrument Technology Co., Ltd. is an all-in-one intelligent flowmeter developed and developed by the most advanced technology at home and abroad. It is in the process of designing product structure, selecting materials, formulating process, production assembly and factory testing. Every link in the process is very meticulous, especially its anti-interference ability has a high level in the field of peers. Here is a way to improve the anti-interference ability of electromagnetic flowmeter.

1. Electromagnetic flowmeter new HCMOS series chip technology

The electromagnetic flowmeter adopts 74HC series chip technology, which adopts 74LS series chip, its low noise margin is increased by 2.4 times, high noise tolerance is increased by 2.1 times, and the intelligent electromagnetic flowmeter adopts 74HC series chip for the whole hardware, which not only reduces the overall power consumption, but also Improve the anti-interference ability of the components themselves, and lay a foundation for the small and lightweight integration of the power flow meter.

2. Intelligent electromagnetic flowmeter advanced microprocessor system power supply voltage monitoring technology

In the microprocessor system of intelligent electromagnetic flowmeter, when the power supply is under voltage, the excitation switch pulse action will cause the microprocessor to malfunction and data loss. Therefore, reliable reset circuit and power supply voltage monitoring technology must be adopted. The simplest and most practical The method is to use a low-cost power supply with a high-sensitivity power supply voltage monitor to improve the microprocessor system and anti-interference ability. The microprocessor voltage monitor uses an advanced power supply voltage monitor chip with power supply and power supply instantaneous undervoltage. Both can produce a reliable reset signal.

3. New excitation technology of electromagnetic flowmeter

The development of electromagnetic flowmeter excitation technology not only weakens the polarization potential of the electrode, mud interference, flow noise, but also changes the shape of power frequency interference, and facilitates the simultaneous sampling technique to deal with power frequency interference noise to avoid the influence of power frequency interference. At present, the electromagnetic flow sensor adopts the power frequency frequency synchronous three-value low-frequency rectangular excitation and the double-frequency rectangular wave excitation, thereby improving the overall anti-interference ability of the electromagnetic flowmeter, improving the measurement accuracy and reliability of the electromagnetic flowmeter. The progress of the electromagnetic flowmeter excitation technology, On the one hand, it changes the shape and characteristics of the orthogonal interference potential, on the other hand, it reduces the magnitude of mud interference and flow noise, thereby improving the anti-interference ability of the electromagnetic flowmeter. Therefore, the improvement of the electromagnetic flowmeter excitation technology is the most effective anti-interference measure.

4. Frequency compensation technology for simultaneous sampling of electromagnetic flowmeter

Synchronous sampling and power frequency power frequency monitoring and compensation technology is an effective method to improve the power frequency interference caused by mixed power frequency interference and power frequency power frequency fluctuation in the anti-flow signal potential. Synchronous sampling technology, the sampling pulse width is the power frequency cycle Integer multiple, so that the average value of power frequency interference in the flow signal potential is equal to zero to eliminate the influence of power frequency interference; the frequency fluctuation compensation of the power frequency power supply is to ensure the dynamic fluctuation of the frequency, the excitation power supply and the sampling pulse can be adjusted synchronously, and the synchronization is realized. Sampling technology and synchronous excitation technology, synchronous A / D conversion to reduce the impact of power frequency interference.

5 electromagnetic flowmeter unique preamplifier design

The output signal of the electromagnetic flow sensor is very weak, the internal impedance is high, so the high input and output impedance. Low drift. Low noise. The high CRMM preamplifier can meet the requirements of anti-inverting common mode interference. The preamplifier uses high input impedance voltage buffer. Low-drift, low-noise subtractor, precision resistors are carefully matched to form an instrument amplifier, and input protection technology, common mode voltage bootstrap technology and grounding technology greatly improve the ability to resist common mode interference and suppress the effect of zero drift.

The development of electromagnetic flowmeter anti-interference technology has greatly promoted the performance improvement of electromagnetic flowmeter. Since its first industrial application, the development of electromagnetic flowmeter anti-jamming technology has gone through several stages, and each progress is to solve its anti-interference. The problem of capability has led to a leap in the anti-interference technology of electromagnetic flowmeters, and the performance index of electromagnetic flowmeters has improved.

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