Pressure transmitter is a kind of common sensor, which is suitable for industrial control environment. There are many kinds of it, resistance strain gage, semiconductor strain gauge, piezoresistive, inductive, capacitive, resonant and capacitive acceleration sensors and so on.
So what are the characteristics of the pressure transmitter?
Pressure transmitter manufacturers in the second-line transmission mode, the power supply, load resistance, transmitters are in series, that is, two of the wires simultaneously transmitting the power supply and output current signal required by the transmitter, at present, most transmitters are two-line transmitter; in four-wire mode, the power supply and the load resistance are connected with the transmitter respectively, namely the power supply and the transmitter output signal respectively with two wire transmission.
In the two-line export is very easy to add one or two lightning protection surge devices, conducive to safe lightning protection explosion-proof, two-line current transmitter is not susceptible to parasitic thermocouples and along the wire resistance pressure drop and temperature drift, can be very inexpensive, more thin wire; can save a lot of cable and installation costs; When the current source output resistor is large enough, the voltage in The wire loop is induced by the magnetic field coupling, and it will not have a noticeable effect, because the current is minimal, and the interference can be decreased by using twisted pairs. The two-wire system and the three-wire system must be shielded by shielding line and the shielding layer should be properly grounded.
In the single-chip microcomputer control of many applications, use transmitters to the single-chip microcomputer can not directly measure the signal converted into a single-chip microcomputer to handle electrical analog signals, such as the current transmitter, pressure transmitter, temperature transmitter, flow transmitter, and so on.