The thermocouple output _ instrument

If it is K type thermocouple, the temperature is below 1250 degrees can use thermoelectric conversion chip max6675, can put the thermocouple signal into 12 digit signal, eliminating the AD conversion, compensation, but also is very good. K type thermocouple AD597 can also be used, can according to the 10 mv/c output voltage, and AD sampling conversion! But for the higher temperature is 1500 degrees with S type thermocouple, the amplifying circuit are difficult, I'm going to use conversion chip AD693, the thermocouple voltage input into 4 - 20 ma current, then use the resistance is converted into voltage. Thermocouple, the output signal of thermocouple and temperature range 1, signal properties: thermocouple platinum resistance, copper resistance, the change of the temperature, the thermocouple produce positive or negative resistance changes; And thermocouple, it is the change of the induced voltage, it along with the change of temperature change. 2, two kinds of sensors to detect temperature range is different, thermocouple testing - in general 200 - The temperature range of 450 degrees, high measurement range of up to 600 degrees ( Of course can detect negative temperature) 。 Thermocouple can detect 0 - Temperature range of 1800 degrees. 3, PLC corresponding thermocouple 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 thermocouple and thermocouple are generally transmitter to access with a PLC. If access to DCS don't have to use the transmitter! Thermocouple is a sign of RTD, thermocouple is TC signal! 4, PLC also has the thermocouple module and thermocouple module, can be directly input resistance and thermocouple signals. Actually for industrial components, to understand the difference, in according to the actual situation of choice is a good way, everybody should pay attention to after accumulation, will be a good choice. Thermocouple and 1, what is the difference between the thermocouple signal output signal, the properties of thermocouple itself is the resistance, the change of the temperature, the thermocouple produce positive or negative resistance changes; And thermocouple, it is the change of the induced voltage, it 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, high measurement range of up to 600 degrees ( Of course can detect negative temperature) 。 Thermocouple can detect 0 - Temperature range of 1000 c ( Even higher) So. 3, from material, thermal resistance is a kind of metal materials, has a temperature sensitive metal materials, thermal coupling is bimetallic material, both two dissimilar metals, due to the changes of temperature, in two different electric potential difference at both ends of the wire. 4, PLC corresponding thermocouple 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 thermocouple and thermocouple are generally transmitter to access with a PLC. If access to DCS don't have to use the transmitter! Thermocouple is a sign of RTD, thermocouple is tc signal! 5, PLC also has the thermocouple module and thermocouple module, which can directly input resistance and thermocouple signals. 6, thermocouple j, t, n, k, s and other models, there are more expensive than resistance, there are also cheaper than resistance, compensation conductor, but on the comprehensive cost of the thermocouple is high.