干扰噪声产生的物理和特性分析工频干扰噪声是由电磁流量计的传感器励磁绕组和流体、电极、放大器输入回路的电磁耦合，另外电磁流量计价格工作现场的工频共模干扰，其三供电电源引入的工频串模干扰等，其产生的物理机理均是电磁感应原理.对于工频共模干扰和工频串模干扰是常见的干扰，主要是由于电磁屏蔽缺陷、分布电容耦合、电磁流量计接地不良等原因产生，采用输入保护技术、高输入阻抗、高共模抑制比自举前置放大器技术以及重复接地技术，工频宽脉冲同步采样技术等提高抗工频干扰的能力。 Physical and characteristic analysis of electromagnetic flowmeter interference noise Power frequency interference noise is the electromagnetic coupling of the sensor's excitation winding of the electromagnetic flowmeter and the input circuit of the fluid, electrode, and amplifier. In addition, the electromagnetic flowmeter prices the power frequency common mode interference at the work site. The power frequency series mode interference introduced by the third power supply, etc., are based on the principle of electromagnetic induction. Common frequency interference and power frequency series mode interference are common interferences, mainly due to electromagnetic shielding defects and distributed capacitance. Coupling, poor grounding of electromagnetic flowmeters, etc., using input protection technology, high input impedance, high common mode rejection ratio bootstrap preamplifier technology, repeated grounding technology, power frequency wide pulse synchronous sampling technology, etc. ability. Using low-frequency rectangular wave excitation, three-value low-frequency rectangular wave excitation, and dual-frequency rectangular wave excitation, orthogonal interference noise evolves into differential interference. Because the differential interference has a period, synchronous sampling technology is used in the constant period of the magnetic field, that is, after the differential interference attenuation is zero, a wide-pulse synchronous sampling is used to avoid the influence of power frequency interference in the flow signal potential. Secondly, the method of controlling the rate of change of the excitation current is used to reduce the amplitude of the differential interference, but the sampling interval of the flow signal is reduced; the program-controlled gain technology can also be used to make the differential interference period gain to Odb and the constant magnetic flux period gain to 100db. To reduce the impact of the magnitude of the differential interference.
是20世纪50~60年代随着电子技术的发展而迅速发展起来的新型流量测量仪表。 Electromagnetic flowmeter is a new type of flow measuring instrument developed rapidly with the development of electronic technology in the 1950s to 1960s. The electromagnetic flowmeter is made according to Faraday's law of electromagnetic induction, and is used to measure the volume flow of conductive liquids. Due to its unique advantages, it has been widely used in industrial flow measurement of various conductive liquids, such as various acids, alkalis, salts and other corrosive media; various slurry flow measurements have formed unique application fields. Structurally, the electromagnetic flowmeter is composed of an electromagnetic flow sensor and a converter. The sensor is installed on the industrial process pipeline, and its role is to linearly convert the volumetric flow value of the liquid flowing into the pipeline into the induced potential signal, and send this signal to the converter through the transmission line. The converter is installed not too far from the sensor. It amplifies the flow signal sent by the sensor and converts it into a standard electrical signal output that is proportional to the flow signal for display, accumulation and adjustment control.
的分类： Classification of electromagnetic flowmeter :
For example, according to the excitation current, there are DC excitation, AC (power frequency or other frequency) excitation, low-frequency rectangular wave excitation, and dual-frequency rectangular wave excitation. Waveforms of several excitation methods. According to the system classification of output signal wiring and excitation (or power) wiring, there are four-wire system and two-wire system. According to the converter and sensor assembly methods, there are separate and integrated types. According to the connection method of flow sensor and pipeline, there are flange connection, flange clamp connection, sanitary connection and thread connection. According to whether the flow sensor electrode is in contact with the measured liquid, there are contact type and non-contact type. According to the structure of the flow sensor, there are short tube type and insertion type. Classified by purpose, there are general-purpose, explosion-proof, sanitary, water-proof and diving.