The method of connecting thermocouples to temperature controllers

1. Introduction to Thermocouples
Thermocouple is a commonly used temperature sensor composed of two different metal alloy wires connected together. When the temperature changes, the thermoelectric potential of the two metals also changes, resulting in small voltage signals. This signal can be read and processed by a temperature controller connected to a thermocouple.

2. Thermocouple wiring color
According to international standards, the wires of thermocouples usually come in two colors, one is red and the other is white. The red wire connects to the positive pole of the thermocouple, while the white wire connects to the negative pole of the thermocouple.

3. Wiring method
There are different types of methods for connecting thermocouples to temperature controllers, and the two common methods are "two wire" and "four wire" connections.

4. Two wire connection method
Two wire connection method is a simple thermocouple connection method and is also a common one. Just connect the positive and negative terminals of the thermocouple to the positive and negative terminals of the temperature controller. This connection method is suitable for situations where the distance between the temperature controller and the thermocouple is relatively close and there is not a high requirement for temperature measurement.

5. Four wire connection method
The four wire connection method is a relatively common thermocouple connection method, suitable for situations with high temperature measurement requirements. This method avoids the influence of wire resistance on the measurement results by separating the current and voltage of the measurement signal.

In the four wire connection method, it is necessary to connect the positive and negative poles of the thermocouple to a measuring circuit. Among them, one pair of wires is responsible for providing measurement current through the current source, and the other pair of wires is responsible for measuring the voltage of the thermocouple. In this way, by analyzing and calculating the current and voltage, accurate temperature measurement results can be obtained.

There are two wire and four wire methods for connecting thermocouples to temperature controllers. When choosing the connection method, it is necessary to choose according to actual needs and measurement requirements. Regardless of the connection method, correctly connecting the thermocouple and temperature controller is the key to ensuring the accuracy of temperature measurement.