What are the differences between thermal resistors and thermocouples?

Both thermocouples and thermal resistors belong to contact temperature measurement in temperature measurement. Although they are both contact temperature measuring instruments, their principles and characteristics are different:

First, the thermocouple based on the thermoelectric effect is a temperature sensor, which is mainly used to measure high temperature; the thermal resistor based on conductors or semiconductors is itself a resistor, which is mainly used to measure small temperature changes.

Second, the thermocouple produces changes in induced voltage, which changes with the change of temperature; and because the thermal resistor itself is a resistor, the resistor produces positive or negative resistance changes;

Third, the temperature measurement range of the two is different. Thermocouples are used in high temperature environments, generally 0-1000 degrees, or even higher; while the temperature range detected by thermal resistors is generally lower.

Fourth, thermocouples have positive and negative poles, and the common ones are short circuit, open circuit, poor contact (can be judged by a multimeter) and deterioration (identified by surface color). When checking, separate the thermocouple from the secondary meter, and then use the multimeter mv range to roughly estimate the thermoelectric potential of the thermocouple; and the short circuit and open circuit of the thermal resistor can be judged by the multimeter.

Fifth, the thermocouple is made of two different metal materials, which is a bimetallic material; while the thermal resistor is a metal material, and also a metal material with temperature sensitive changes.