Wiring picture of thermocouple temperature transmitter

Project Overview

　　In the field of industrial automation control, temperature measurement is one of the crucial links. Thermocouples, as a commonly used temperature sensor, have the advantages of simple structure, wide measurement range, and fast response speed, and are applied in various industrial production processes. The thermocouple temperature transmitter can convert the weak thermoelectric potential generated by the thermocouple into standard current or voltage signals, which facilitates subsequent instrument acquisition and processing. This article will provide a detailed introduction to the wiring method of thermocouple temperature transmitters and provide clear wiring pictures to help you quickly master the correct wiring techniques.

　　1. Working principle of thermocouple and temperature transmitter

　　Before delving deeper into the wiring methods, let's briefly review the working principles of thermocouples and temperature transmitters.

　　1.1 Working principle of thermocouple

　　A thermocouple is a closed circuit composed of two different metal materials. When the temperatures at both ends are different, an electromotive force will be generated in the circuit, which is called the Seebeck effect. The generated thermoelectric potential is proportional to the temperature difference, and by measuring the magnitude of the thermoelectric potential, the measured temperature can be calculated.

　　1.2 Working principle of temperature transmitter

　　The temperature transmitter receives weak thermoelectric potential signals from thermocouples, amplifies, linearizes, and compensates for the cold end, and finally converts them into standard 4-20mA current signals or 0-5V/0-10V voltage signals for output, in order to facilitate the acquisition and processing of control systems such as PLC and DCS.

　　2. Types of thermocouple temperature transmitters

　　There are many types of thermocouple temperature transmitters on the market, which are mainly divided into the following types according to different installation methods:

　　Rail type temperature transmitter: compact in size, easy to install, suitable for situations with limited space. Disk mounted temperature transmitter: With powerful functions and high accuracy, it is suitable for occasions that require centralized control. Head mounted temperature transmitter: directly installed on the thermocouple connector, with short signal transmission distance and strong anti-interference ability. 3. Wiring diagram of thermocouple temperature transmitter

　　The wiring method of thermocouple temperature transmitter mainly depends on its input and output signal types and specific models. Here are some common ones for your reference:

　　3.1 Wiring diagram of two-wire thermocouple temperature transmitter

　　The two-wire thermocouple temperature transmitter adopts a loop power supply method, which only requires two wires to complete signal transmission and power supply. When wiring, connect the positive and negative poles of the thermocouple to the "+" and "-" terminals of the transmitter respectively.

　　3.2 Wiring diagram of three wire thermocouple temperature transmitter

　　The three wire thermocouple temperature transmitter requires an independent power supply, with two wires for power input and one wire for signal output. When wiring, connect the positive terminal of the thermocouple to the "+" terminal of the transmitter, the negative terminal to the "-" terminal, the positive terminal of the power supply to the "+V" terminal, the negative terminal of the power supply to the "- V" terminal, and the signal output line to the "OUT" terminal.

　　3.3 Wiring diagram of four wire thermocouple temperature transmitter

　　Four wire thermocouple temperature transmitters are commonly used for long-distance signal transmission, with two wires for power input and two wires for signal output. The wiring method is similar to the three wire system, except that there are two signal output lines connected to the "OUT+" and "OUT -" terminals, respectively.

　　4. Precautions for wiring thermocouple temperature transmitters

　　To ensure the accuracy of wiring and the stability of the system, the following points should be noted when wiring:

　　Choose the appropriate thermocouple type and scale: Different thermocouple types and scale correspond to different temperature measurement ranges and accuracies, and should be selected according to actual needs. Ensure secure and reliable wiring: Loose wiring can cause unstable signal transmission and affect measurement accuracy. Take good shielding and grounding measures: In order to avoid the impact of external electromagnetic interference on signal transmission, shielding and grounding measures should be taken. Strictly follow the product manual for wiring: There may be differences in wiring methods for different models of thermocouple temperature transmitters, so it is necessary to carefully read the product manual and strictly follow the requirements for wiring. 5. Summary

　　The wiring of thermocouple temperature transmitters may seem simple, but improper operation can affect measurement accuracy and even cause system failures. This article provides a detailed introduction to the wiring method and precautions of thermocouple temperature transmitters, and provides clear wiring pictures, hoping to help you complete the wiring operation correctly and ensure the normal operation of the system.