The difference between thermal resistors and thermocouples

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Difference between thermal resistors and thermocouples: 1. Nature of the signal – A thermal resistor is essentially a resistor, and changes in temperature cause a positive or negative change in its resistance value； A thermocouple, on the other hand, generates a change in induced voltage that varies with temperature. II. The temperature ranges detected by the two types of sensors are different; thermistors generally detect temperatures in the range of 0-150 degrees, while thermocouples can detect temperatures in the range of 0-1000 degrees. So, the former is low-temperature detection, and the latter is high-temperature detection. III. In terms of material, a thermal resistor is a metal material that exhibits temperature-sensitive changes; a thermocouple, on the other hand, is made of two different metals, and due to temperature changes, a potential difference is generated at the ends of these two different metal wires. IV. The input modules for thermoresistors and thermocouples that are used with PLCs are also different; however, most PLCs accept 4–20 mA signals directly, while thermoresistors and thermocouples usually require transmitters in order to be connected to a PLC. If it’s connected to DCS, there’s no need for a transmitter! Thermal resistors produce RTD signals, while thermocouples generate TC signals! V. PLCs also have thermal resistor modules and thermocouple modules, which can directly accept resistor and thermocouple signals.