The development history of electromagnetic flowmeter.

The development history of electromagnetic flowmeter is the development history of its anti - jamming technology. As early as 1832, the British physicist Faraday conceived the earth's magnetic field to measure the velocity of the Thames river and carried out field experiments, but failed. The main reason is that the polarization effect and the thermoelectric effect of the fluid medium under the dc excitation magnetic field are caused by the interference noise. River short circuit flow velocity signal voltage and the flow technology far from achieving a solution to all kinds of jamming noise suppression and high impedance signal measurement level, thus lead to the failure of the electromagnetic flowmeter experimental research for the first time. Indeed, from the start of the study of electromagnetic flowmeter face thorny problem how to overcome all kinds of noise interference, because of this, in the later in the study of electromagnetic flowmeter, people will be its anti-interference technology as the primary technical problems.

The development of electromagnetic flowmeter excitation technology greatly promotes its anti-interference technology. The late '50 s and electromagnetic flowmeter industrial application for the first time, the anti-jamming technology of electromagnetic flowmeter development has experienced several stages, each time the progress is in order to solve the problem of the anti-interference ability of the prompted electromagnetic flowmeter anti-interference techniques appeared a leap, electromagnetic flowmeter performance index improved. The late '50 s and 60 s, in order to reduce the dc excitation magnetic field on the surface of the electrode polarization potential, the influence of power frequency sine wave excitation technology is adopted, but caused the electromagnetic induction and electrostatic coupling power frequency interference, which adopt the complex orthogonal interference suppression circuit such as a variety of anti-jamming measures, it is difficult to completely eliminate the effects of power frequency interference noise, causing electromagnetic flowmeter zero to stability, low precision, poor reliability. In the mid - 70 - s, with the development of electronic technology and the advent of synchronous sampling technology, USES the low-frequency rectangular wave excitation technology, change the morphological characteristics of power frequency interference, using synchronous sampling technology, the power frequency for electromagnetic flow object good ability to resist power frequency interference, measurement accuracy, zero point stability, reliability is enhanced. In the early 80 s by three values low-frequency rectangular wave excitation technology and dynamic zero technology, synchronous excitation, synchronous sampling technology to obtain the best electromagnetic flowmeter zero point stability, further improve the power frequency interference and polarization potential interference resistance. Using dual frequency rectangular wave excitation technology, in the late 80 s, can not only overcome the mud interference produced fluid and fluid flow noise, and can have zero voltage of low-frequency rectangular wave excitation electromagnetic flowmeter, electromagnetic flowmeter zero point stability, anti-interference ability and response speed of the best. So electromagnetic flowmeter excitation technology advances, on the one hand, change the configuration of orthogonal interference electric potential and characteristics, on the other hand, reduce the mud of the order of magnitude of interference and flow noise, so as to improve the anti-jamming ability of electromagnetic flow meter, so the improvement of electromagnetic flowmeter excitation technology is the most effective anti-interference measures.