The knowledge about pressure transmitters is inexhaustible and can be further understood.Pressure transmitter measuring principle is: the process pressure and reference, respectively applied to the ends of the integrated silicon pressure sensor, the differential pressure make the silicon wafer deformation (displacement is very small, only microns), so that the silicon wafers made of semiconductor technology, full-motion wheatstone bridge in external driven by current source output voltage signal is proportional to the pressure of the mV level.Due to the excellent strength of silicon material, the linearity and variation index of the output signal are very high.When working, the pressure transmitter converts the measured physical quantity into mV class voltage signal and sends it to the differential amplifier with high amplification factor and can offset the temperature drift.The amplified signal is converted into the corresponding current signal through voltage and current conversion, and then nonlinear correction is conducted. Finally, the standard current and voltage signal with a linear correspondence relation with the input pressure is generated.
Pressure transmitter mV, V, mA and frequency output digital output, the choice of the output depends on a variety of factors, including the transmitter and the system controller or display distance, whether there is "noise" or other electronic interference signals, whether the need for amplifier, amplifier position.For many OEM equipment with short distance between transmitter and controller, mA output transmitter is an economical and effective solution.
In an environment with high RFI or EMI indicators, special protection or filters should be considered in addition to selecting mA or frequency output.
If the output signal needs to be amplified, use a transmitter with built-in amplification.MA level output or frequency output is used for long distance transmission or strong electronic interference signal.
Pressure transmitter is widely used, almost all of them are used in a variety of industrial environments, because a series of problems of the pressure transmitter will be obvious, which is also a test of the performance and service life of the pressure transmitter.
In the process of using the pressure transmitter, we will find that after the pressure transmitter is put into operation, the measurement is not accurate, or the signal output is not stable. In addition to its own quality problems, it is generally interfered by the influence of the interference source.
1. Rf interference mainly refers to the interference of starting and stopping operation of large power equipment and high-order harmonic interference, such as the interference of SCR rectifier system.
2. Electrostatic induction of the sensor. Electrostatic induction is caused by the parasitic capacitance between two branch circuits or components, so that the charge on one branch is transmitted to the other branch through the parasitic capacitance, so it is also called capacitive coupling.
3. Leakage of electricity: due to the poor insulation of component supports, terminal posts, printed circuit boards, capacitor internal media or shell in electronic circuits, especially the application environment of sensors with high humidity, the insulation resistance of insulators will drop, and the increase of leakage current will cause interference.Especially when the leakage current flows into the input stage of the measurement circuit, the effect is very serious.
4. Electromagnetic induction, when there is mutual inductance between two circuits, the change of current in one circuit will be coupled to the other circuit through the magnetic field, this phenomenon is called electromagnetic induction.For example, magnetic leakage of transformers and coils, parallel wires for power supply, etc.
5. Finally, there may be some other interference. In addition to the above, the on-site safety production monitoring system is vulnerable to mechanical interference, thermal interference and chemical interference due to the poor working environment of the system.
Pressure transmitter because of different product models and process requirements, product prices are not the same, the manufacturer can be based on user requirements for special processing.
I. pressure range: small pressure and large pressure difference to be measured.The general pressure transmitter has 1.5 times the overload capacity.
Ii. Operating temperature range: low operating temperature and high operating temperature.Usually - 20 ~ 80 ℃. If the temperature is high, need to add other cooling measures.
Iii. Measured medium: with the different measured medium, the pressure transmitter requirements are different.For example, acid and alkali resistance, ceramic sensor is better.The shell of acid and alkali resistance.
Iv. Measurement accuracy: in general occasions, the accuracy of 0.5% is more.If more accurate measurement is required, a measurement accuracy of 0.2% or 0.1% can be required.
Output signal: it refers to the signal that can be received by the relevant secondary instrument.Most use 4-20ma, but there are other 0-5v, 0-10v or 0-20ma output signals.
Six, Interface size: according to the customer site use conditions, processing the corresponding installation size.
What is a pressure transmitter?In fact, this word for us, generally feel very strange, but usually in life should pay attention to understand this kind of knowledge, so that they will not suffer losses when they buy again, so what is the pressure transmitter?Pressure transmitter is in the industrial use of a sensor, generally contact with industry friends will know, it is more common in the life of the water and electricity, building use, and if the lack of the products, will not be able to run, it is a very key products, this requires that everyone at the time of purchase, must buy good quality, if the quality, you buy will affect the use, so never can do not pay attention to choose and buy blindly, now advertising special much, everybody to want to compare prices and quality to buy, this is necessary to understand.