Large-aperture electromagnetic flow transmitter

External magnetic structure transmitter due to the stainless steel tube eddy Current loss caused by the adverse consequences: the excitation current increased, active power increased a lot, the measurement tube of eddy current loss increased a lot, than the total loss of the measurement tube is much larger. The angle of phase difference between voltage and current becomes smaller. The performance of the transmitter and the stability of the complete set of instruments are disadvantageous. When the transmitter's caliber is larger, the loss is greater and the phase angle becomes smaller, due to a greater difference between the current of the loss and the flux (including the flow signal). With you this excitation system has a large impact on the current parameters of the measurement tube.
In order to improve the performance, the large-aperture electromagnetic flow transmitter adopts the internal magnetic structure. The so-called internal magnetic structure refers to the transmitter's shell and the measurement tube into one, magnetic yoke, coil and other exciting system components are installed inside the shell, eliminating the thick wall of stainless steel measuring tube. Instead of 1mm thin-walled stainless steel cylinders. The shielding effect of the electric field reduces the interference of the same phase. The casing is filled with a stainless steel bushing and is lined with insulating lining on the inner lining of the liner. In the workshop, the fluid pressure in the pipe is passed evenly through the lining, bushing and filled resin to the shell, because the shell is under pressure, there are two main types of liner currently used:

1.Polyurethane rubber; Its processing method is to adopt integral vacuum pouring. The inner and outer sides of the bushing are full of elastic, high strength, excellent wear-resistant polyurethane rubber. Alternatively, the polyurethane rubber is used only as an insulating liner, and the bushing and the casing are cast resin.
2.Acid-resistant rubber. A space vacuum casting resin between the bushing and the casing. The inner cylinder of the bushing and the flange end are lined with acid resistant rubber. The transmitter is structured in such a way that there are two electrode boxes on each side of the horizontal cross-section of the housing center for mounting electrodes and wiring. The flow signal detected by the electrode passes through the lead circuit between the yoke and the coil to the junction box. The top of the transmitter has two junction boxes, one is only the signal junction box, the inside has the interference potentiometer and the wiring end plate; the other is the excitation power supply junction box, potting the excitation coil at both ends of the resin to lead to the junction box.
The internal magnetic structure of the transmitter equipment has the following advantages:1.Using the whole structure, assembled with synthetic rubber or resin pouring, the structure is simple and reliable, such as a straight pipe, usually do not need to be repaired by what.2.The casing is combined with the measuring tube, which reduces the mechanical cutting process, saves the expensive stainless steel material, the volume is small, the weight is lighter.3.There is no sealing problem of measuring tube and surface of outer magnetic transmitter. So good sealing, waterproof performance. Can be made into water seal, installed in the pit, to meet the water supply, drainage system underground burial requirements.4.The main advantages are improved performance, low power consumption, good instrument stability.The main disadvantage of this kind of internal magnetic structure transmitter is that the process performance requirements are high. Excitation system, electrode lead and so on are pouring in the resin, pouring good or bad, affect the performance of the whole transmitter, once the problem or failure, there will be the entire transmitter scrap possible.
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