Can you add current to a pressure transmitter?

Can the pressure transmitter add current?

The pressure transmitter is one of the important on-site measurement instruments in industrial automation control. Its main function is to convert the pressure signal into a standard electrical signal output for subsequent processing by the control system. In practical applications, we often encounter problems about the power supply and signal output of the pressure transmitter, such as "Can the pressure transmitter add current?", "How to convert the current signal into a pressure value?" and so on. This article will focus on these issues and explain the relevant knowledge of pressure transmitters in simple terms to help everyone better understand and use this type of instrument.

The working principle of the pressure transmitter

To know whether the pressure transmitter can add current, let's first understand its working principle. Simply put, the pressure transmitter contains a sensitive element (such as a diaphragm, piezoresistive sensor, etc.) and a signal conversion circuit. When pressure acts on a sensitive element, it will cause its deformation or resistance change, and the signal conversion circuit converts this change into an electrical signal output. According to the different types of output signals, pressure transmitters can be mainly divided into the following categories:

Current output type: outputs standard current signals such as 4-20mA, 0-20mA, etc. The applications of this type of transmitter are: . Voltage output type: outputs 0-5V, 1-5V and other standard voltage signals. Digital output type: Outputs RS-485, HART and other digital signals, which can realize remote monitoring and parameter setting.

The pressure transmitter cannot directly add current

As can be seen from the above classification, the current output pressure transmitter itself will output a current signal, so we cannot directly " Add current". If current is applied forcefully, the transmitter may be damaged. So, why is the current output transmitter used in this way? This is because current signals have stronger anti-interference capabilities than voltage signals and have longer transmission distances, making them suitable for complex electromagnetic environments in industrial sites.

Power supply and signal output of the pressure transmitter

Pressure transmitters usually use two-wire or four-wire wiring methods:

Two-wire system: The power line and signal line share two wires, and the transmitter obtains its working power from the loop current. This method of wiring is simple, but the output current will be affected by the loop resistance. Four-wire system: The power line and signal line use two wires respectively, and the transmitter has an independent power supply. This method is not affected by the loop resistance and the output signal is more accurate, but the wiring is relatively complicated.

It should be noted that no matter which wiring method is used, we cannot directly add current to the signal output end. For application scenarios that need to convert current signals into pressure values, we can use the following methods:

Use an ammeter to directly read the current value, and then calculate the corresponding pressure based on the range and output characteristic curve of the transmitter. value. Use control systems such as PLC and DCS to collect current signals and calculate the corresponding pressure values ​​through programs. Convert current signal to voltage signal using dedicated current/voltage converter, and then use a voltmeter or other instrument to measure it.

Choose a suitable pressure transmitter

When selecting a pressure transmitter, in addition to considering the output signal type, you also need to select the appropriate range, accuracy, and pressure transmitter according to actual application requirements. Material, interface form and other parameters. The following are some selection suggestions:

Select the appropriate material according to the properties of the medium being measured, such as stainless steel, Hastelloy, etc. Select the appropriate range according to the range of the pressure being measured. Choosing too large a range will affect the measurement accuracy. Select the appropriate output signal type and accuracy level according to the control system requirements. Choose pressure transmitters from well-known brands to ensure product quality and after-sales service.

Summary

As an important pressure measuring instrument, pressure transmitter plays an irreplaceable role in the field of industrial automation control. Understanding its working principle, power supply method, signal output type and selection method can help us better apply this type of instrument and improve the reliability and stability of the automated control system. I hope this article can help you answer your question about "Can a pressure transmitter add current?" and help you choose and use an appropriate pressure transmitter in practical applications.