A thermocouple chart is a practical tool for the electronic query of temperature index. It is used by technicians who are engaged in automatic control of the production process.

To simply look at it means: when 0 is the reference temperature and the measured temperature is the sum of the row and column temperatures, the measured thermoelectric potential is the value.

## How do you read a K type thermocouple table?

In the thermocouple chart, the first row and the first column are all temperature values.
The rows are incremented by 10 degrees per grid.
The columns are incremented by 100 degrees per grid.
The intersection of the row and the column is the thermoelectric potential value at the current temperature.

Take the S-type couple to read the thermoelectric potential value at 280 degrees Celsius for example: first find 200 degrees from the first column, and draw a straight line to the right.
Then find 80 degrees from the first line and draw a straight line down. Where the two lines meet, the thermoelectric potential value at 280 degrees is 2.141 millivolts.

## Type K thermocouple chart

K Reference terminal temperature: 0℃, 10 degrees μν value

## Type N thermocouple chart

N reference terminal temperature: 0℃, 10 degrees μν value

## Type E thermocouple chart

E Reference terminal temperature: 0℃, 10 degrees μν value

## Type J thermocouple chart

J Reference terminal temperature: 0℃, 10 degrees μν value

## Type T thermocouple chart

T reference terminal temperature: 0℃, 10 degrees μν value

## Type S thermocouple chart

S Reference terminal temperature: 0℃, 10 degrees μν value

## Type R thermocouple chart

R Reference terminal temperature: 0℃, 10 degrees μν value

## Type B thermocouple chart

B reference terminal temperature: 0℃, 10 degrees μν value

## The working principle of thermocouple (thermocouple principle)

What is a thermocouple?
This is to start with the principle of thermocouple temperature measurement. The thermocouple is a kind of temperature sensing element and a primary instrument. It directly measures temperature and converts the temperature signal into a term electromotive force signal. It is converted into a term electromotive force signal by an electrical instrument (secondary instrument). The temperature of the measured medium.

The basic principle of thermocouple temperature measurement is that two different components of material conductors form a closed loop. When there is a temperature gradient at both ends, there will be a current passing through the loop, and then there is Seebeck electromotive force-term electromotive force between the two ends. This is the so-called Seebeck effect.

Two homogeneous conductors with different compositions are term electrodes, the end with a higher temperature is the working end, and the end with a lower temperature is the free end, which is usually at a certain constant temperature. According to the functional relationship between term electromotive force and temperature, a thermocouple index table is made. The index table is obtained when the free end temperature is at 0℃. Different thermocouples have different index tables.

When the third metal material is connected in the thermocouple circuit, as long as the temperature of the two junctions of the material is the same, the thermoelectric potential generated by the thermocouple will remain unchanged, that is, it will not be affected by the third metal in the circuit. Therefore, when the thermocouple measures the temperature, it can be connected to the measuring instrument, and after the term electromotive force is measured, the temperature of the measured medium can be known.

The working principle of thermocouple:

Two conductors with different components (called thermocouple wires or thermoelectrodes) are connected at both ends to form a loop. When the temperature of the junction is different, an electromotive force will be generated in the loop. This phenomenon is called the thermoelectric effect. And The electromotive force is called thermoelectric force.

Thermocouples use this principle for temperature measurement. One end that is directly used to measure the temperature of the medium is called the working end (also called the measuring end), and the other end is called the cold end (also called the compensation end). The cold end and the display instrument or When the matching instrument is connected, the display instrument will point out the thermoelectric potential generated by the thermocouple.

A thermocouple is actually a kind of energy converter, which converts heat energy into electrical energy. Use the generated thermoelectric potential to measure temperature. Regarding the thermoelectric potential of a thermocouple, you should pay attention to the following issues:

1. The thermoelectric potential of a thermocouple is a function of the temperature difference between the two ends of the thermocouple. It is not a function of the temperature difference between the two ends of the thermocouple;
2. The size of the thermoelectric potential generated by the thermocouple. When the material of the thermocouple is uniform, it has nothing to do with the length and diameter of the thermocouple, but is only related to the composition of the thermocouple material and the temperature difference between the two ends;
3. When the two thermocouple wires of the thermocouple have determined the material composition. The thermoelectric potential of the thermocouple is only related to the temperature difference of the thermocouple. If the temperature of the cold junction of the thermocouple remains constant, the thermoelectric potential of the thermocouple is only Single-valued function of working end temperature.