What is a two-wire thermocouple？How Two-Wire Thermocouples Work？

What is a two-wire thermocouple

For some special-purpose thermocouples, such as those used for flame detection, one pair wire can be made into the probe shell, and the other is connected (welded) from the middle of the shell to the end of the probe. When installing, the shell is used as a The other pole is led out by a wire, which is called a single-wire thermocouple; it is also possible to connect (weld) two wires to the end of the probe at the same time, and lead it out with two wires, which is called a double-wire thermocouple.

How Two-Wire Thermocouples Work

The burner of the domestic gas stove is usually equipped with an ignition needle and a thermocouple flameout protection needle. The thermocouple is a very important part of the gas stove, and the quality of the thermocouple is related to the ignition reaction time and ignition success rate of the gas stove. A thermocouple is actually a temperature-sensing element, which directly measures the temperature, converts the temperature signal into a thermoelectromotive force signal, and converts it into the temperature of the measured medium through an electrical instrument.

Thermocouples are made from a combination of two different alloy materials. Different alloy materials will produce different thermoelectric potentials under the action of temperature, and thermocouples are manufactured by using different thermoelectric potentials produced by different alloy materials under the action of temperature. The two ends of conductors with different components are joined to form a circuit. When the temperature of the junction is different, an electromotive force will be generated in the circuit. This phenomenon is called thermoelectric effect, and this electromotive force is called thermoelectric force. Thermocouples use this principle to measure temperature. Among them, one end directly used to measure the temperature of the medium is called the working end, and the other end is called the cold end; the thermoelectric potential.

The height of the thermocouple should be basically the same as the height of the fire cover, and attention should be paid to maintaining the distance between the thermocouple and the fire cover. The distance between the thermocouple and the fire cover should not be too far away. Generally, it is better to keep the distance of 4±0.5mm. If the installation position is too low, the thermocouple will not be heated enough to generate enough thermoelectric potential, which will not make the solenoid valve close. If the installation position is too high , The flame contact is too large, it is easy to burn out the thermocouple, the same reason, too far away, the thermoelectric potential will not be enough, and the solenoid valve will not be closed.