The difference between the thermocouple and thermal resistance

Thermocouple temperature sensor is a kind of test, as well as thermal resistance temperature sensor, but he and thermal resistance difference mainly lies in:

a, signal, the properties of heat resistance itself is resistance, the change of the temperature, the thermal resistance produce positive or negative resistance changes; And thermocouple, it is the change of the induced voltage, he along with the change of temperature change.

2, two kinds of sensors to detect temperature range, thermal resistance 0 - general detection The temperature range of 150 degrees, the highest measurement range can be up to 600 degrees ( Of course can detect negative temperature) 。

thermocouple can detect 0 - Temperature range of 1000 c ( Even higher) So, rosemount 3051 transmitter is low temperature test, the latter is high temperature testing.

3, from material, heat resistance is a kind of metal material, is sensitive to temperature changes of metal materials, thermal coupling is bimetallic material, both of two different metals, due to the changes of temperature, in two different electric potential difference at both ends of the wire.

4, PLC corresponding thermal resistance and thermocouple input module is also different, this sentence is no problem, but the general PLC are directly connected to the 4 ~ 20 ma signal, and the thermal resistance and thermocouple are generally transmitter to access with a PLC. If access to DCS don't have to use the transmitter! Thermal resistance is RTD signals, thermocouple is TC signal!

5, PLC also has the thermal resistance and thermocouple module, which can directly input resistance and thermocouple signals.

6, thermocouple J, T, N, K type thermocouple, S and other models, rosemount temperature transmitter is more expensive than resistance, there are also cheaper than resistance, compensation conductor, but on the comprehensive cost of the thermocouple is high.

related knowledge: the working principle of thermocouple