The main cause of affecting thermocouple response time

Major influential factors of thermocouple response time are mainly have the following:

1, the structure, size of thermocouple. Hot electrode, the diameter of the protecting tube more thick, the greater the inertia; The greater the tube wall thickness, inertia also. The interval of reaching stability state of the thermocouple is long, the response time is long.

2, different materials, heat conduction performance is also different. Such as metal protection tube is better than ceramic protection tube thermal conductivity, thermal inertia small, the interval of reaching stability state of thermocouple is short, short response time.

3, response time, also along with the change of working condition is different, that is to say the same of the structure of the thermocouple, under the condition of different heat exchange, the response time is different.

there was a step change in temperature, thermocouple output changes to correspond to the step change in the time needed for a prescribed percentage referred to as the thermocouple, thermal response time, usually by T.

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 0 - can be detected 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.