The type b compensation wire must be correctly selected according to the type of thermocouple used and the occasion used. For example, the compensation wire of the k-type couple should be selected, and the operating temperature range should be selected according to the application. Usually the working temperature of kx is -20~100℃, and the wide range is -25~200℃. The error of ordinary grade is ±2.5℃, and that of precision grade is ±1.5℃.

As close as possible to the two contacts of the thermocouple terminal, try to maintain the temperature of the two contacts*. The temperature at the connection with the instrument terminal should be as high as possible. Where the instrument cabinet has a fan, the contact should be protected so that the fan does not blow directly to the contact. In order to improve the anti-interference of the thermocouple connection wire, shielded compensation wire can be used. For occasions with many on-site interference sources, the effect is better. However, the shielding layer must be strictly grounded, otherwise the shielding layer will not only not play a role in shielding, but will increase the interference.

Because the signal of the thermocouple is very low, at the microvolt level, if the distance used is too long, the attenuation of the signal and the interference coupling of the strong current in the environment can distort the signal of the thermocouple, resulting in inaccurate temperature measurement and control. Temperature fluctuations will occur when the control is severe.

According to our experience, it is usually better to control the length of the thermocouple compensation wire within 15 meters. If it exceeds 15 meters, it is recommended to use a temperature transmitter to transmit the signal. The temperature transmitter converts the potential value corresponding to the temperature into a DC current for transmission, and has strong anti-interference.